CRISPR/RNA-GUIDED NUCLEASE-RELATED METHODS AND COMPOSITIONS FOR TREATING RHO-ASSOCIATED

AUTOSOMAL-DOMINANT RETINITIS PIGMENTOSA (ADRP)

PRIORITY CLAIM

This application claims priority to U.S. Provisional Patent Application No. 63/175,749, filed April 16, 2021, and U.S. Provisional Patent Application No. 63/266,264, filed December 30, 2021, both of which are incorporated by reference herein in their entirety.

SEQUENCE LISTING

This application contains a Sequence Listing, which was submitted in ASCII format via EFS-Web, and is hereby incorporated by reference in its entirety. The ASCII copy, created on April 15, 2022, is named SequenceListing.txt and is 272 KB in size.

FIELD

The disclosure relates to CRISPR/RNA-guided nuclease-related methods and components for editing a target nucleic acid sequence, and applications thereof in connection with autosomal dominant retinitis pigmentosa (ADRP).

BACKGROUND

Retinitis pigmentosa (RP), an inherited retinal dystrophy that affects photoreceptors and retinal pigment epithelium cells, is characterized by progressive retinal deterioration and atrophy, resulting in a gradual loss of vision and ultimately leading to blindness in affected patients. RP can be caused by both homozygous and heterozygous mutations and can present in various forms, for example, as autosomal-dominant RP (adRP), autosomal recessive RP (arRP) or X-linked RP (X-LRP). Treatment options for RP are limited, and no approved treatment that can arrest or reverse RP progression is currently available.

SUMMARY

Some aspects of the strategies, methods, compositions, and treatment modalities provided herein address a key unmet need in the field by providing new and effective means of delivering genome editing systems to the affected cells and tissues of subjects suffering from autosomal-dominant retinitis pigmentosa (adRP). Some aspects of this disclosure provide strategies, methods, and compositions for the introduction of genome editing systems targeted to the adRP associated gene rhodopsin into retinal cells. Such strategies, methods, and compositions are useful, in some embodiments, for editing adRP associated variants of the rhodopsin gene, e.g., for inducing gene editing events that result in loss-of-function of such rhodopsin variants. In some embodiments, such strategies, methods, and compositions are useful as treatment modalities for administration to a subject in need thereof, e.g., to a subject having an autosomal-dominant form of RP. The strategies, methods, compositions, and treatment modalities provided herein thus represent an important step forward in the development of clinical interventions for the treatment of RP, e.g., for the treatment of adRP.

Provided herein in certain aspects are compositions comprising: a first nucleic acid comprising a sequence encoding an RNA-guided nuclease; and a second nucleic acid comprising a sequence encoding a first guide RNA (gRNA) comprising a first targeting domain that is complementary to a target domain in the RHO gene; and a RHO complementary DNA (cDNA).

In certain embodiments, the RNA-guided nuclease may comprise an RNA-guided nuclease set forth in Table 4. In certain embodiments, the RNA-guided nuclease may be Cas9. In certain embodiments, the Cas9 may be an S. aureus Cas9 (SaCas9). In certain embodiments, the sequence encoding the Cas9 may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NO: 1008. In certain embodiments, the Cas9 may comprise a nickase. In certain embodiments, the sequence encoding the RNA-guided nuclease may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with an RNA-guided nuclease in Table 4.

In certain embodiments, the first nucleic acid may comprise a promoter operably linked to the sequence that encodes the RNA-guided nuclease. In certain embodiments, the promoter operably linked to the RNA-guided nuclease may be a rod-specific promoter. In certain embodiments, the rod-specific promoter may be a human RHO promoter. In certain embodiments, the human RHO promoter may comprise an endogenous RHO promoter. In certain embodiments, the promoter operably linked to the sequence that encodes the RNA- guided nuclease may comprise a promoter selected from the group consisting of RHO, CMV, EFS, GRK1, CRX, NRL, and RCVRN promoter. In certain embodiments, the promoter operably linked to the sequence that encodes the RNA-guided nuclease may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:43-50, 1004.

In certain embodiments, the first nucleic acid may comprise a 3’ untranslated region (UTR) nucleotide sequence downstream of the sequence encoding the RNA-guided nuclease. In certain embodiments, the 3’ UTR nucleotide sequence may comprise a RHO gene 3’ UTR nucleotide sequence. In certain embodiments, the 3’ UTR nucleotide sequence may comprise an a-globin 3’ UTR nucleotide sequence. In certain embodiments, the 3’ UTR nucleotide sequence may comprise a b-globin 3’ UTR nucleotide sequence. In certain embodiments, the 3’ UTR nucleotide sequence may comprise one or more truncations at a 5’ end of the 3’ UTR nucleotide sequence, at a 3’ end of the 3’ UTR nucleotide sequence, or both. In certain embodiments, the 3’ UTR nucleotide sequence may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:38-42, or 56.

In certain embodiments, the first nucleic acid may comprise a 5’ inverted terminal repeat (ITR) sequence. In certain embodiments, the 5’ ITR sequence may comprise, or consist of, a nucleotide sequence that is the same as, or may differ by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or may share at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:59-67, 92, or 1011.

In certain embodiments, the first nucleic acid may comprise a 3’ ITR sequence. In certain embodiments, the 3’ ITR sequence may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:68-76, or 93.

In certain embodiments, the first nucleic acid may comprise one or more polyadenylation (poly A) sequences. In certain embodiments, the poly A sequence may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:56, 57, or 58.

In certain embodiments, the first nucleic acid may comprise a SV40 intron sequence. In certain embodiments, the SV40 intron sequence may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NO:94. In certain embodiments, the first nucleic acid may comprise: (i) a 5’ ITR, (ii) a promoter operably linked to the sequence that encodes the RNA-guided nuclease, (iii) a SV40 intron sequence, (iv) a sequence encoding the RNA-guided nuclease; (v) one or more polyA sequences; and (vi) a 3’ ITR.

In certain embodiments, the first nucleic acid may comprise: (i) a 5’ ITR, (ii) a promoter operably linked to the sequence that encodes the RNA-guided nuclease, (iii) a SV40 intron sequence, (iv) a sequence encoding the RNA-guided nuclease; (v) a 3’ UTR; (vi) one or more polyA sequences; and (vii) a 3’ ITR.

In certain embodiments, the first nucleic acid may comprise:

(i) a 5’ ITR sequence comprising, or consisting of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:92 or 1011;

(ii) a promoter operably linked to the sequence that encodes the RNA-guided nuclease molecule comprising, or consisting of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%,

90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NO: 1004;

(iii) a SV40 intron comprising, or consisting of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NO:94;

(iv) a sequence encoding the RNA-guided nuclease comprising, or consisting of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NO: 1008;

(v) one or more polyA sequences comprising, or consisting of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:56; and

(vi) a 3’ UTR nucleotide sequence comprising, or consisting of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NO:38; and/or (vii) a 3’ ITR sequence comprising, or consisting of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:93.

In certain embodiments, the first nucleic acid may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:9, 10, 1005, or 1009.

In certain embodiments, the first targeting domain may comprise a sequence that is the same as, or differs by no more than 3 nucleotides from, a first targeting domain sequence set forth in any of SEQ ID NOs: 100-502.

In certain embodiments, the second nucleic acid may further comprise a sequence encoding a second gRNA comprising a second targeting domain that is complementary to a target domain in the RHO gene. In certain embodiments, the second targeting domain may comprise a sequence that is the same as, or differs by no more than 3 nucleotides from, a second targeting domain sequence set forth in any of SEQ ID NOs: 100-502. In certain embodiments, the first and second gRNA targeting domains comprise different sequences. In certain embodiments, the first and second gRNA targeting domains comprise the same sequence. In certain embodiments, the first targeting domain may comprise or consist of 17 to 26 nucleotides, 18 to 26 nucleotides, 19 to 26 nucleotides, 20 to 26 nucleotides, 21 to 26 nucleotides, 22 to 26 nucleotides, 23 to 26 nucleotides, 24 to 26 nucleotides, 25 to 26 nucleotides, 17 to 25 nucleotides, 18 to 25 nucleotides, 19 to 25 nucleotides, 20 to 25 nucleotides, 21 to 25 nucleotides, 22 to 25 nucleotides, 23 to 25 nucleotides, 24 to 25 nucleotides, 17 to 24 nucleotides, 18 to 24 nucleotides, 19 to 24 nucleotides, 20 to 24 nucleotides, 21 to 24 nucleotides, 22 to 24 nucleotides, 23 to 24 nucleotides, 17 to 23 nucleotides, 18 to 23 nucleotides, 19 to 23 nucleotides, 20 to 23 nucleotides, 21 to 23 nucleotides, 22 to 23 nucleotides, 17 to 22 nucleotides, 18 to 22 nucleotides, 19 to 22 nucleotides, 20 to 22 nucleotides, 21 to 22 nucleotides, 17 to 21 nucleotides, 18 to 21 nucleotides, 19 to 21 nucleotides, 20 to 21 nucleotides, 17 to 20 nucleotides, 18 to 20 nucleotides, 19 to 20 nucleotides, 17 to 19 nucleotides, 18 to 19 nucleotides, or 17 to 18 nucleotides. In certain embodiments, the second targeting domain may comprise or consist of 17 to 26 nucleotides, 18 to 26 nucleotides, 19 to 26 nucleotides, 20 to 26 nucleotides, 21 to 26 nucleotides, 22 to 26 nucleotides, 23 to 26 nucleotides, 24 to 26 nucleotides, 25 to 26 nucleotides, 17 to 25 nucleotides, 18 to 25 nucleotides, 19 to 25 nucleotides, 20 to 25 nucleotides, 21 to 25 nucleotides, 22 to 25 nucleotides, 23 to 25 nucleotides, 24 to 25 nucleotides, 17 to 24 nucleotides, 18 to 24 nucleotides, 19 to 24 nucleotides, 20 to 24 nucleotides, 21 to 24 nucleotides, 22 to 24 nucleotides, 23 to 24 nucleotides, 17 to 23 nucleotides, 18 to 23 nucleotides, 19 to 23 nucleotides, 20 to 23 nucleotides, 21 to 23 nucleotides, 22 to 23 nucleotides, 17 to 22 nucleotides, 18 to 22 nucleotides, 19 to 22 nucleotides, 20 to 22 nucleotides, 21 to 22 nucleotides, 17 to 21 nucleotides, 18 to 21 nucleotides, 19 to 21 nucleotides, 20 to 21 nucleotides, 17 to 20 nucleotides, 18 to 20 nucleotides, 19 to 20 nucleotides, 17 to 19 nucleotides, 18 to 19 nucleotides, or 17 to 18 nucleotides. In certain embodiments, the first targeting domain, the second targeting domain, or the first targeting domain and second targeting domain may comprise or consist of 22 to 26 nucleotides and may comprise a sequence selected from the group consisting of SEQ ID NOs: 101, 102, 106, 107, and 109. In certain embodiments, the first targeting domain, the second targeting domain, or the first targeting domain and second targeting domain may comprise or consist of SEQ ID NO: 101. In certain embodiments, the first targeting domain, the second targeting domain, or the first targeting domain and second targeting domain may comprise or consist of SEQ ID NO: 102. In certain embodiments, the first targeting domain, the second targeting domain, or the first targeting domain and second targeting domain may comprise or consist of SEQ ID NO: 106. In certain embodiments, the first targeting domain, the second targeting domain, or the first targeting domain and second targeting domain may comprise or consist of SEQ ID NO: 107. In certain embodiments, the first targeting domain, the second targeting domain, or the first targeting domain and second targeting domain may comprise or consist of SEQ ID NO: 109.

In certain embodiments, the first gRNA, the second gRNA, or the first gRNA and second gRNA may be a modular gRNA. In certain embodiments, the first gRNA, the second gRNA, or the first gRNA and second gRNA may be a chimeric gRNA. In certain embodiments, the first gRNA may comprise from 5’ to 3’: a targeting domain; a first complementarity domain; a linking domain; a second complementarity domain; a proximal domain; and a tail domain.

In certain embodiments, the second gRNA comprising from 5’ to 3’: a targeting domain; a first complementarity domain; a linking domain; a second complementarity domain; a proximal domain; and a tail domain.

In certain embodiments, the first gRNA, the second gRNA, or the first gRNA and the second gRNA may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NO:88 or 90.

In certain embodiments, the second nucleic acid may comprise a promoter operably linked to the sequence that encodes the first gRNA. In certain embodiments, the second nucleic acid may comprise a promoter operably linked to the sequence that encodes the second gRNA. In certain embodiments, the promoter operably linked to the sequence that encodes the first gRNA, the second gRNA, or the first gRNA and second gRNA may be a U6 promoter. In certain embodiments, the U6 promoter may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NO:78.

In certain embodiments, the RHO cDNA may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:2, 4-7, or 13-18.

In certain embodiments, the RHO cDNA molecule may not be codon modified to be resistant to hybridization with the first and second gRNA molecules. In certain embodiments, the RHO cDNA may be codon modified to be resistant to hybridization with the first and second gRNA.

In certain embodiments, the RHO cDNA may comprise a nucleotide sequence comprising exon 1, exon 2, exon 3, exon 4, and exon 5 of the RHO gene. In certain embodiments, the RHO cDNA may comprise a nucleotide sequence comprising exon 1, intron 1, exon 2, exon 3, exon 4, and exon 5 of the RHO gene. In certain embodiments, the RHO cDNA may comprise one or more introns. In certain embodiments, the one or more introns may comprise one or more truncations at a 5’ end of the intron, a 3’ end of the intron, or both. In certain embodiments, intron 1 may comprise one or more truncations at a 5’ end of intron 1, a 3’ end of intron 1, or both.

In certain embodiments, the second nucleic acid may comprise a 3’ untranslated region (UTR) nucleotide sequence downstream of the RHO cDNA. In certain embodiments, the 3’ UTR nucleotide sequence comprises a RHO gene 3’ UTR nucleotide sequence. In certain embodiments, the 3’ UTR nucleotide sequence may comprise an a-globin 3’ UTR nucleotide sequence. In certain embodiments, the 3’ UTR nucleotide sequence may comprise a b-globin 3’ UTR nucleotide sequence. In certain embodiments, the 3’ UTR nucleotide sequence may comprise one or more truncations at a 5’ end of the 3’ UTR nucleotide sequence, a 3’ end of the 3’ UTR nucleotide sequence, or both. In certain embodiments, the 3 ’ UTR nucleotide sequence may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:38-42, or 56.

In certain embodiments, the second nucleic acid may comprise a promoter operably linked to the RHO cDNA. In certain embodiments, the promoter operably linked to the RHO cDNA may be a rod-specific promoter. In certain embodiments, the rod-specific promoter may be a human RHO promoter. In certain embodiments, the human RHO promoter may comprise an endogenous RHO promoter. In certain embodiments, the promoter operably linked to the RHO cDNA may comprise a promoter selected from the group consisting of RHO, CMV, EFS, GRK1, CRX, NRL, and RCVRN promoter. In certain embodiments, the promoter operably linked to the RHO cDNA may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:43-50, or 1004.

In certain embodiments, the second nucleic acid may comprise a 5’ ITR sequence. In certain embodiments, the 5’ ITR sequence may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:59-67, 92, or 1011.

In certain embodiments, the second nucleic acid may comprise a 3’ ITR sequence. In certain embodiments, the 3’ ITR sequence may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:68-76, or 93.

In certain embodiments, the second nucleic acid may comprise one or more polyadenylation (poly A) sequences. In certain embodiments, the poly A sequence may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:56, 57, or 58.

In certain embodiments, the second nucleic acid may comprise a SV40 intron sequence. In certain embodiments, the SV40 intron sequence may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NO:94.

In certain embodiments, the second nucleic acid may comprise (i) a 5’ ITR sequence, (ii) a promoter operably linked to the sequence that encodes the first gRNA, (iii) the sequence that encodes the first gRNA, (iv) a promoter operably linked to the RHO cDNA, (v) a SV40 intron sequence, (vi) the RHO cDNA, (vii) a 3 ’ UTR sequence, (viii) one or more polyA sequences, and (ix) a 3’ ITR sequence. In certain embodiments, the second nucleic acid may comprise (i) a 5 ’ ITR sequence, (ii) a promoter operably linked to the sequence that encodes the first gRNA, (iii) the sequence that encodes the first gRNA, (iv) a promoter operably linked to the sequence that encodes the second gRNA, (v) the sequence that encodes the second gRNA, (vi) a promoter operably linked to the RHO cDNA, (vii) a SV40 intron sequence, (viii) the RHO cDNA, (ix) a 3’ UTR sequence, (x) one or more polyA sequences, and (xi) a 3 ’ ITR sequence.

In certain embodiments, the second nucleic acid may comprise (i) the sequence that encodes the first gRNA, (ii) the RHO cDNA, and (iii) one or more of the sequences selected from the group consisting of a promoter operably linked to the sequence that encodes the first gRNA, the sequence that encodes the second gRNA, a promoter operably linked to the sequence that encodes the second gRNA, a 5’ ITR sequence, a promoter operably linked to the RHO cDNA, a SV40 intron sequence, a 3’ UTR sequence, one or more polyA sequences, and a 3’ ITR sequence.

In certain embodiments, the second nucleic acid may comprise (i) a 5’ ITR sequence, (ii) a promoter operably linked to the sequence that encodes the first gRNA, (iii) the sequence that encodes the first gRNA, (iv) a promoter operably linked to the RHO cDNA, (v) a SV40 intron sequence, (vi) the RHO cDNA, (vii) a 3 ’ UTR sequence, (viii) one or more polyA sequences, and (ix) a 3’ ITR sequence.

In certain embodiments, the second nucleic acid may comprise (i) a 5’ ITR sequence,

(ii) a promoter operably linked to the sequence that encodes the first gRNA, (iii) the sequence that encodes the first gRNA, (iv) a promoter operably linked to the sequence that encodes the second gRNA, (v) the sequence that encodes the second gRNA, (vi) a promoter operably linked to the RHO cDNA, (vii) a SV40 intron sequence, (viii) the RHO cDNA, (ix) a 3’ UTR sequence, (x) one or more polyA sequences, and (xi) a 3’ ITR sequence.

In certain embodiments, the second nucleic acid may comprise (i) a 5’ ITR sequence comprising, or consisting of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:59-67, 92, or 1011,

(ii) a promoter operably linked to the sequence that encodes the first gRNA comprising, or consisting of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NO:78,

(iii) a sequence that encodes the first gRNA comprising or consisting of a sequence that is the same as, or differs by no more than 3 nucleotides from, a second targeting domain sequence set forth in any of SEQ ID NOs: 100-502,

(iv) a promoter operably linked to the sequence that encodes the second gRNA comprising, or consisting of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NO:78,

(v) a sequence that encodes the second gRNA comprising or consisting of a sequence that is the same as, or differs by no more than 3 nucleotides from, a second targeting domain sequence set forth in any of SEQ ID NOs: 100-502,

(vi) a promoter operably linked to the RHO cDNA comprising, or consisting of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:43-50, or 1004,

(vii) a SV40 intron sequence comprising, or consisting of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NO:94, (viii) the RHO cDNA comprising, or consisting of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:2, 4-7, or 13-18,

(ix) a 3’ UTR sequence comprising, or consisting of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:38-42, or 56,

(x) one or more polyA sequences comprising, or consisting of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:56, 57, or 58, and/or

(xi) a 3’ ITR sequence comprising, or consisting of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:68-76, or 93.

In certain embodiments, the second nucleic acid may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:8, 11, 1006, 1010.

In certain embodiments, the first nucleotide sequence may be a first viral vector, the second nucleotide sequence may be a second viral vector, or the first nucleotide sequence may be a first viral vector and the second nucleotide sequence may be a second viral vector. In certain embodiments, the first and second viral vectors may be selected from the group consisting of an AAV vector, an adenovirus vector, a vaccinia vims vector, and a herpes simplex virus vector. In certain embodiments, the AAV vector may be an AAV5 vector. In certain embodiments, the first nucleotide sequence may be a first AAV5 vector. In certain embodiments, the second nucleotide sequence may be a second AAV5 vector.

Provided herein in certain aspects are pharmaceutical compositions comprising any of the compositions disclosed herein. In certain embodiments, the first viral vector and second viral vector of the pharmaceutical composition may be present at a ratio (first viral vector:second viral vector) selected from the group consisting of 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, and 2:1. In certain embodiments, the first viral vector and second viral vector of the pharmaceutical composition may be present at a ratio (first viral vectorsecond viral vector) selected from the group consisting of 1: 1, 1:2, 1:3, 1:4, 1:5, 5:1, 4:1, 3:1, and 2:1. In certain embodiments, the first viral vector and second viral vector of the pharmaceutical composition may be present at a ratio (first viral vectorsecond viral vector) selected from the group consisting of 1:1, 1:2, 1:3, and 1:4. In certain embodiments, the first viral vector and second viral vector of the pharmaceutical composition may have a total concentration of 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL. In certain embodiments, the first viral vector and second viral vector of the pharmaceutical composition may have a total concentration of lxlO ¹¹ viral genomes (vg)/mL to 6xl0 ¹² vg/mL. In certain embodiments, the first viral vector and second viral vector of the pharmaceutical composition may have total concentration of 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL. In certain embodiments, the first viral vector and second viral vector of the pharmaceutical composition may have total concentration selected from the group consisting of 6xl0 ¹⁰ vg/mL to 9xl0 ¹³ vg/mL, 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL, lxlO ¹¹ vg/mL to 3xl0 ¹² vg/mL, 9xlO ⁿ vg/mL to 3xl0 ¹² vg/mL, and όcΐq ¹¹ vg/mL to 3xl0 ¹² vg/mL. In certain embodiments, the first viral vector and second viral vector of the pharmaceutical composition may have total concentration selected from the group consisting of 6xl0 ¹⁰ vg/mL, 7xl0 ¹⁰ vg/mL, 8xl0 ¹⁰ vg/mL, 9xl0 ¹⁰ vg/mL, lxlO ¹¹ vg/mL, 2xlO ⁿ vg/mL, 3xl0 ⁿ vg/mL, 4xlO ⁿ vg/mL, 5xl0 ⁿ vg/mL, 6xlO ⁿ vg/mL, 7xlO ⁿ vg/mL, 8xl0 ⁿ vg/mL, 9xlO ⁿ vg/mL, lxlO ¹² vg/mL, 2xl0 ¹² vg/mL, 3xl0 ¹² vg/mL, 4xl0 ¹² vg/mL, 5xl0 ¹² vg/mL, and 6xl0 ¹² vg/mL. In certain embodiments, the first viral vector and second viral vector of the pharmaceutical composition may have total concentration selected from the group consisting of from 6xl0 ¹⁰ vg/mL to 3xl0 ⁿ vg/mL, from 3xl0 ⁿ vg/mL to όcΐq ¹¹ vg/mL, from 6xlO ⁿ vg/mL to lxlO ¹² vg/mL, from lxlO ¹² vg/mL to 3xl0 ¹² vg/mL, or from 3xl0 ¹² vg/mL to 6xl0 ¹² vg/mL. In certain embodiments, the first viral vector and second viral vector of the pharmaceutical composition may be present at a ratio (first viral vectorsecond viral vector) selected from the group consisting of 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, and 2:1. In certain embodiments, the first viral vector and second viral vector of the pharmaceutical composition may be present at a ratio (first viral vectorsecond viral vector) selected from the group consisting of 1: 1, 1:2, 1:3, 1:4, 1:5, 5:1, 4:1, 3:1, and 2:1. In certain embodiments, the first viral vector and second viral vector of the pharmaceutical composition may have a total concentration and ratio (first viral vectorsecond viral vector) selected from the group consisting of: the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector: second viral vector) of 1:1; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector:second viral vector) of 1:2; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector: second viral vector) of 1:3; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector:second viral vector) of 1:4; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector: second viral vector) of 1:5; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector: second viral vector) of 1:6; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector:second viral vector) of 1:7; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector: second viral vector) of 1:8; the total concentration of from 6 to 6xl0 ¹² vg/mL and the ratio (first viral vector:second viral vector) of 1:9; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector:second viral vector) of 1:10; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector:second viral vector) of 10:1; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector:second viral vector) of 9:1; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector: second viral vector) of 8:1; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector: second viral vector) of 7:1; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector:second viral vector) of 6:1; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector: second viral vector) of 5:1; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector:second viral vector) of 4:1; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector: second viral vector) of 3:1; and the total concentration of from 6x10 ¹⁰ vg/mL to 6x10 ¹² vg/mL and the ratio (first viral vector:second viral vector) of 2:1. In certain embodiments, the first viral vector and second viral vector of the pharmaceutical composition may have a ratio (first viral vector:second viral vector) selected from the group consisting of 1:1, 1:2, 1:3, and 1:4. In certain embodiments, the first viral vector and second viral vector of the pharmaceutical composition may have a total concentration and ratio (first viral vector:second viral vector) selected from the group consisting of: selected from the group consisting of: 6x10 ¹⁰ vg/mL, ratio of 1:1; 6x10 ¹⁰ vg/mL, ratio of 1:2; 6x10 ¹⁰ vg/mL, ratio of 1:3; 6x10 ¹⁰ vg/mL, ratio of 1:4; 6x10 ¹⁰ vg/mL, ratio of 1:5; 6x10 ¹⁰ vg/mL, ratio of 5:1; 6x10 ¹⁰ vg/mL, ratio of 4:1; 6x10 ¹⁰ vg/mL, ratio of 3:1; and 6x10 ¹⁰ vg/mL, ratio of 2:1; 7x10 ¹⁰ vg/mL, ratio of 1:1; 7x10 ¹⁰ vg/mL, ratio of 1:2; 7x10 ¹⁰ vg/mL, ratio of 1:3; 7x10 ¹⁰ vg/mL, ratio of 1:4; 7x10 ¹⁰ vg/mL, ratio of 1:5; 7x10 ¹⁰ vg/mL, ratio of 5:1; 7x10 ¹⁰ vg/mL, ratio of 4:1; 7x10 ¹⁰ vg/mL, ratio of 3:1; 7x10 ¹⁰ vg/mL, ratio of 2:1; 8x10 ¹⁰ vg/mL, ratio of 1:1; 8x10 ¹⁰ vg/mL, ratio of 1:2; 8x10 ¹⁰ vg/mL, ratio of 1:3; 8x10 ¹⁰ vg/mL, ratio of 1:4; 8x10 ¹⁰ vg/mL, ratio of 1:5; 8x10 ¹⁰ vg/mL, ratio of 5:1; 8x10 ¹⁰ vg/mL, ratio of 4:1; 8x10 ¹⁰ vg/mL, ratio of 3:1; 8x10 ¹⁰ vg/mL, ratio of 2:1; 9x10 ¹⁰ vg/mL, ratio of 1:1; 9x10 ¹⁰ vg/mL, ratio of 1:2; 9x10 ¹⁰ vg/mL, ratio of 1:3; 9x10 ¹⁰ vg/mL, ratio of 1:4; 9x10 ¹⁰ vg/mL, ratio of 1:5; 9x10 ¹⁰ vg/mL, ratio of 5:1; 9x10 ¹⁰ vg/mL, ratio of 4:1; 9x10 ¹⁰ vg/mL, ratio of 3:1; 9x10 ¹⁰ vg/mL, ratio of 2:1; 1x10 ¹¹ vg/mL, ratio of 1:1; 1x10 ¹¹ vg/mL, ratio of 1:2; 1x10 ¹¹ vg/mL, ratio of 1:3; 1x10 ¹¹ vg/mL, ratio of 1:4; 1x10 ¹¹ vg/mL, ratio of 1:5; 1x10 ¹¹ vg/mL, ratio of 5:1; 1x10 ¹¹ vg/mL, ratio of 4:1; 1x10 ¹¹ vg/mL, ratio of 3:1; 1x10 ¹¹ vg/mL, ratio of 2:1; 3x10 ¹¹ vg/mL, ratio of 1:1; 2x10 ¹¹ vg/mL, ratio of 1:1; 2x10 ¹¹ vg/mL, ratio of 1:2; 2x10 ¹¹ vg/mL, ratio of 1:3; 2x10 ¹¹ vg/mL, ratio of 1:4; 2x10 ¹¹ vg/mL, ratio of 1:5; 2x10 ¹¹ vg/mL, ratio of 5:1; 2x10 ¹¹ vg/mL, ratio of 4:1; 2x10 ¹¹ vg/mL, ratio of 3:1; 2x10 ¹¹ vg/mL, ratio of 2:1; 3x10 ¹¹ vg/mL, ratio of 1:1; 3x10 ¹¹ vg/mL, ratio of 1:2; 3x10 ¹¹ vg/mL, ratio of 1:3; 3x10 ¹¹ vg/mL, ratio of 1:4; 3x10 ¹¹ vg/mL, ratio of 1:5; 3x10 ¹¹ vg/mL, ratio of 5:1; 3x10 ¹¹ vg/mL, ratio of 4:1; 3x10 ¹¹ vg/mL, ratio of 3:1; 3x10 ¹¹ vg/mL, ratio of 2:1; 4x10 ¹¹ vg/mL, ratio of 1:1; 4x10 ¹¹ vg/mL, ratio of 1:2; 4x10 ¹¹ vg/mL, ratio of 1:3; 4x10 ¹¹ vg/mL, ratio of 1:4; 4x10 ¹¹ vg/mL, ratio of 1:5; 4x10 ¹¹ vg/mL, ratio of 5:1; 4x10 ¹¹ vg/mL, ratio of 4:1; 4x10 ¹¹ vg/mL, ratio of 3:1; 4x10 ¹¹ vg/mL, ratio of 2:1; 5x10 ¹¹ vg/mL, ratio of 1:1; 5x10 ¹¹ vg/mL, ratio of 1:2; 5x10 ¹¹ vg/mL, ratio of 1:3; 5x10 ¹¹ vg/mL, ratio of 1:4; 5x10 ¹¹ vg/mL, ratio of 1:5; 5x10 ¹¹ vg/mL, ratio of 5:1; 5x10 ¹¹ vg/mL, ratio of 4:1; 5x10 ¹¹ vg/mL, ratio of 3:1; 5x10 ¹¹ vg/mL, ratio of 2:1; 6x10 ¹¹ vg/mL, ratio of 1:1; 6x10 ¹¹ vg/mL, ratio of 1:2; 6x10 ¹¹ vg/mL, ratio of 1:3; 6x10 ¹¹ vg/mL, ratio of 1:4; 6x10 ¹¹ vg/mL, ratio of 1:5; 6x10 ¹¹ vg/mL, ratio of 5:1; 6x10 ¹¹ vg/mL, ratio of 4:1; 6x10 ¹¹ vg/mL, ratio of 3:1; 6x10 ¹¹ vg/mL, ratio of 2:1; 7x10 ¹¹ vg/mL, ratio of 1:1; 7x10 ¹¹ vg/mL, ratio of 1:2; 7x10 ¹¹ vg/mL, ratio of 1:3; 7x10 ¹¹ vg/mL, ratio of 1:4; 7x10 ¹¹ vg/mL, ratio of 1:5; 7x10 ¹¹ vg/mL, ratio of 5:1; 7x10 ¹¹ vg/mL, ratio of 4:1; 7x10 ¹¹ vg/mL, ratio of 3:1; 7x10 ¹¹ vg/mL, ratio of 2:1; 8x10 ¹¹ vg/mL, ratio of 1:1; 8x10 ¹¹ vg/mL, ratio of 1:2; 8x10 ¹¹ vg/mL, ratio of 1:3; 8x10 ¹¹ vg/mL, ratio of 1:4; 8x10 ¹¹ vg/mL, ratio of 1:5; 8x10 ¹¹ vg/mL, ratio of 5:1; 8x10 ¹¹ vg/mL, ratio of 4:1; 8x10 ¹¹ vg/mL, ratio of 3:1; 8x10 ¹¹ vg/mL, ratio of 2:1; 9x10 ¹¹ vg/mL, ratio of 1:1; 9x10 ¹¹ vg/mL, ratio of 1:2; 9x10 ¹¹ vg/mL, ratio of 1:3; 9x10 ¹¹ vg/mL, ratio of 1:4; 9x10 ¹¹ vg/mL, ratio of 1:5; 9x10 ¹¹ vg/mL, ratio of 5:1; 9x10 ¹¹ vg/mL, ratio of 4:1; 9x10 ¹¹ vg/mL, ratio of 3:1; 9x10 ¹¹ vg/mL, ratio of 2:1; 1x10 ¹² vg/mL, ratio of 1:1; 1x10 ¹² vg/mL, ratio of 1:2; 1x10 ¹² vg/mL, ratio of 1:3; 1x10 ¹² vg/mL, ratio of 1:4; 1x10 ¹² vg/mL, ratio of 1:5; 1x10 ¹² vg/mL, ratio of 5:1; 1x10 ¹² vg/mL, ratio of 4:1; 1x10 ¹² vg/mL, ratio of 3:1; 1x10 ¹² vg/mL, ratio of 2:1; 2x10 ¹² vg/mL, ratio of 1:1; 2x10 ¹² vg/mL, ratio of 1:2; 2x10 ¹² vg/mL, ratio of 1:3; 2x10 ¹² vg/mL, ratio of 1:4; 2x10 ¹² vg/mL, ratio of 1:5; 2x10 ¹² vg/mL, ratio of 5:1; 2x10 ¹² vg/mL, ratio of 4:1; 2x10 ¹² vg/mL, ratio of 3:1; 2x10 ¹² vg/mL, ratio of 2:1; 3x10 ¹² vg/mL, ratio of 1:1; 3x10 ¹² vg/mL, ratio of 1:2; 3x10 ¹² vg/mL, ratio of 1:3; 3x10 ¹² vg/mL, ratio of 1:4; 3x10 ¹² vg/mL, ratio of 1:5; 3x10 ¹² vg/mL, ratio of 5:1; 3x10 ¹² vg/mL, ratio of 4:1; 3x10 ¹² vg/mL, ratio of 3:1; 3x10 ¹² vg/mL, ratio of 2:1; 4x10 ¹² vg/mL, ratio of 1:1; 4x10 ¹² vg/mL, ratio of 1:2; 4x10 ¹² vg/mL, ratio of 1:3; 4x10 ¹² vg/mL, ratio of 1:4; 4x10 ¹² vg/mL, ratio of 1:5; 4x10 ¹² vg/mL, ratio of 5:1; 4x10 ¹² vg/mL, ratio of 4:1; 4x10 ¹² vg/mL, ratio of 3:1; 4x10 ¹² vg/mL, ratio of 2:1; 5x10 ¹² vg/mL, ratio of 1:1; 5x10 ¹² vg/mL, ratio of 1:2; 5x10 ¹² vg/mL, ratio of 1:3; 5x10 ¹² vg/mL, ratio of 1:4; 5x10 ¹² vg/mL, ratio of 1:5; 5x10 ¹² vg/mL, ratio of 5:1; 5x10 ¹² vg/mL, ratio of 4:1; 5x10 ¹² vg/mL, ratio of 3:1; 5x10 ¹² vg/mL, ratio of 2:1; 6x10 ¹² vg/mL, ratio of 1:1; 6x10 ¹² vg/mL, ratio of 1:2; 6x10 ¹² vg/mL, ratio of 1:3; 6x10 ¹² vg/mL, ratio of 1:4; 6x10 ¹² vg/mL, ratio of 1:5; 6x10 ¹² vg/mL, ratio of 5:1; 6x10 ¹² vg/mL, ratio of 4:1; 6x10 ¹² vg/mL, ratio of 3:1; and 6x10 ¹² vg/mL, ratio of 2:1. In certain embodiments, the first viral vector and second viral vector of the pharmaceutical composition may have a total concentration and ratio (first viral vector:second viral vector) selected from the group consisting of 3.0x10 ¹¹ vg/mL (first viral vector) and 3.0x10 ¹¹ vg/mL (second viral vector) (1:1 ratio, total concentration 6x10 ¹¹ ), 2.0x10 ¹¹ vg/mL (first viral vector) and 4.0x10 ¹¹ vg/mL (second viral vector) (1:2 ratio, total concentration 6x10 ¹¹ ), 1.5x ¹¹ vg/mL (first viral vector) and 4.5x10 ¹¹ vg/mL (second viral vector) (1:3 ratio, total concentration 6x10 ¹¹ ), 1.2x10 ¹¹ vg/mL (first viral vector) and 4.8x10 ¹¹ vg/mL (second viral vector) (1:4 ratio, total concentration 6x10 ¹¹ ), 0.5x10 ¹² vg/mL (first viral vector) and 0.5x10 ¹² vg/mL (second viral vector) (1:1 ratio, total concentration 1x10 ¹² ), 0.333x10 ¹² vg/mL (first viral vector) and 0.666x10 ¹² vg/mL (second viral vector) (1:2 ratio, total concentration 1x10 ¹² ), 0.25x10 ¹² vg/mL (first viral vector) and 0.75x10 ¹² vg/mL (second viral vector) (1:3 ratio, total concentration 1x10 ¹² ), 0.2x10 ¹² vg/mL (first viral vector) and 0.8x10 ¹² vg/mL (second viral vector) (1:4 ratio, total concentration 1x10 ¹² ), 1.5x10 ¹² vg/mL (first viral vector) and 1.5x10 ¹² vg/mL (second viral vector) (1:1 ratio, total concentration 3x10 ¹² ), 1.0x10 ¹² vg/mL (first viral vector) and 2.0x10 ¹² vg/mL (second viral vector) (1:2 ratio, total concentration 3x10 ¹² ), 0.75x10 ¹² vg/mL (first viral vector) and 2.25x10 ¹² vg/mL (second viral vector) (1:3 ratio, total concentration 3x10 ¹² ), 0.6x10 ¹² vg/mL (first viral vector) and 2.4x10 ¹² vg/mL (second viral vector) (1:4 ratio, total concentration 3x10 ¹² ), 3.0x10 ¹² vg/mL (first viral vector) and 3.0x10 ¹² vg/mL (second viral vector) (1:1 ratio, total concentration 6x10 ¹² ), 2.0x10 ¹² vg/mL (first viral vector) and 4.0x10 ¹² vg/mL (second viral vector) (1:2 ratio, total concentration 6x10 ¹² ), 1.5x ¹² vg/mL (first viral vector) and 4.5x10 ¹² vg/mL (second viral vector) (1:3 ratio, total concentration 6x10 ¹² ), and 1.2x10 ¹² vg/mL (first viral vector) and 4.8x10 ¹² vg/mL (second viral vector) (1:4 ratio, total concentration 6x10 ¹² ). Provided herein in certain aspects are methods of treating retinitis pigmentosa (RP) in a subject in need thereof comprising administering to the subject the compositions disclosed herein. In certain embodiments, the RP may be selected from the group consisting of autosomal-dominant RP (adRP), autosomal recessive RP (arRP), and X-linked RP (X-LRP). In certain embodiments, the first viral vector and second viral vector may be administered to the subject at a total concentration of 1x10 ¹¹ viral genomes (vg)/mL to 6x10 ¹² vg/mL. In certain embodiments, the first viral vector and second viral vector may be administered to the subject at a total concentration of 6x10 ¹⁰ vg/mL to 6x10 ¹² vg/mL. In certain embodiments, the first viral vector and second viral vector may be administered to the subject at a total concentration selected from the group consisting of 6x10 ¹⁰ vg/mL to 9x10 ¹³ vg/mL, 6x10 ¹⁰ vg/mL to 6x10 ¹² vg/mL, 1x10 ¹¹ vg/mL to 3x10 ¹² vg/mL, 9x10 ¹¹ vg/mL to 3x10 ¹² vg/mL, and 6x10 ¹¹ vg/mL to 3x10 ¹² vg/mL. In certain embodiments, the first viral vector and second viral vector may be administered to the subject at a total concentration selected from the group consisting of 6x10 ¹⁰ vg/mL, 7x10 ¹⁰ vg/mL, 8x10 ¹⁰ vg/mL, 9x10 ¹⁰ vg/mL, 1x10 ¹¹ vg/mL, 2x10 ¹¹ vg/mL, 3x10 ¹¹ vg/mL, 4x10 ¹¹ vg/mL, 5x10 ¹¹ vg/mL, 6x10 ¹¹ vg/mL, 7x10 ¹¹ vg/mL, 8x10 ¹¹ vg/mL, 9x10 ¹¹ vg/mL, 1x10 ¹² vg/mL, 2x10 ¹² vg/mL, 3x10 ¹² vg/mL, 4x10 ¹² vg/mL, 5x10 ¹² vg/mL, and 6x10 ¹² vg/mL. In certain embodiments, the first viral vector and second viral vector may be administered to the subject at a total concentration selected from the group consisting of from 6x10 ¹⁰ vg/mL to 3x10 ¹¹ vg/mL, from 3x10 ¹¹ vg/mL to 6x10 ¹¹ vg/mL, from 6x10 ¹¹ vg/mL to 1x10 ¹² vg/mL, from 1x10 ¹² vg/mL to 3x10 ¹² vg/mL, or from 3x10 ¹² vg/mL to 6x10 ¹² vg/mL. In certain embodiments, the first viral vector and second viral vector may be administered at a ratio (first viral vector:second viral vector) selected from the group consisting of 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, and 2:1. In certain embodiments, the first viral vector and second viral vector may be administered at a ratio (first viral vector:second viral vector) selected from the group consisting of 1:1, 1:2, 1:3, 1:4, 1:5, 5:1, 4:1, 3:1, and 2:1. In certain embodiments, the first viral vector and second viral vector may be administered at a total concentration and ratio (first viral vector:second viral vector) selected from the group consisting of: the total concentration of from 6x10 ¹⁰ vg/mL to 6x10 ¹² vg/mL and the ratio (first viral vector:second viral vector) of 1:1; the total concentration of from 6x10 ¹⁰ vg/mL to 6x10 ¹² vg/mL and the ratio (first viral vector:second viral vector) of 1:2; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector: second viral vector) of 1:3; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector:second viral vector) of 1:4; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector: second viral vector) of 1:5; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector: second viral vector) of 1:6; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector:second viral vector) of 1:7; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector: second viral vector) of 1:8; the total concentration of from 6 to 6xl0 ¹² vg/mL and the ratio (first viral vector:second viral vector) of 1:9; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector:second viral vector) of 1:10; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector:second viral vector) of 10:1; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector:second viral vector) of 9:1; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector: second viral vector) of 8:1; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector: second viral vector) of 7:1; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector:second viral vector) of 6:1; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector: second viral vector) of 5:1; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector:second viral vector) of 4:1; the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector: second viral vector) of 3:1; and the total concentration of from 6xl0 ¹⁰ vg/mL to 6xl0 ¹² vg/mL and the ratio (first viral vector:second viral vector) of 2:1. In certain embodiments, the first viral vector and second viral vector may be administered at a ratio (first viral vector:second viral vector) selected from the group consisting of 1:1, 1:2, 1:3, and 1:4. In certain embodiments, the first viral vector and second viral vector may be administered at a total concentration and ratio (first viral vector:second viral vector) selected from the group consisting of: 6x10 ¹⁰ vg/mL, ratio of 1:1; 6x10 ¹⁰ vg/mL, ratio of 1:2; 6x10 ¹⁰ vg/mL, ratio of 1:3; 6x10 ¹⁰ vg/mL, ratio of 1:4; 6x10 ¹⁰ vg/mL, ratio of 1:5; 6x10 ¹⁰ vg/mL, ratio of 5:1; 6x10 ¹⁰ vg/mL, ratio of 4:1; 6x10 ¹⁰ vg/mL, ratio of 3:1; and 6x10 ¹⁰ vg/mL, ratio of 2:1; 7x10 ¹⁰ vg/mL, ratio of 1:1; 7x10 ¹⁰ vg/mL, ratio of 1:2; 7x10 ¹⁰ vg/mL, ratio of 1:3; 7x10 ¹⁰ vg/mL, ratio of 1:4; 7x10 ¹⁰ vg/mL, ratio of 1:5; 7x10 ¹⁰ vg/mL, ratio of 5:1; 7x10 ¹⁰ vg/mL, ratio of 4:1; 7x10 ¹⁰ vg/mL, ratio of 3:1; 7x10 ¹⁰ vg/mL, ratio of 2:1; 8x10 ¹⁰ vg/mL, ratio of 1:1; 8x10 ¹⁰ vg/mL, ratio of 1:2; 8x10 ¹⁰ vg/mL, ratio of 1:3; 8x10 ¹⁰ vg/mL, ratio of 1:4; 8x10 ¹⁰ vg/mL, ratio of 1:5; 8x10 ¹⁰ vg/mL, ratio of 5:1; 8x10 ¹⁰ vg/mL, ratio of 4:1; 8x10 ¹⁰ vg/mL, ratio of 3:1; 8x10 ¹⁰ vg/mL, ratio of 2:1; 9x10 ¹⁰ vg/mL, ratio of 1:1; 9x10 ¹⁰ vg/mL, ratio of 1:2; 9x10 ¹⁰ vg/mL, ratio of 1:3; 9x10 ¹⁰ vg/mL, ratio of 1:4; 9x10 ¹⁰ vg/mL, ratio of 1:5; 9x10 ¹⁰ vg/mL, ratio of 5:1; 9x10 ¹⁰ vg/mL, ratio of 4:1; 9x10 ¹⁰ vg/mL, ratio of 3:1; 9x10 ¹⁰ vg/mL, ratio of 2:1; 1x10 ¹¹ vg/mL, ratio of 1:1; 1x10 ¹¹ vg/mL, ratio of 1:2; 1x10 ¹¹ vg/mL, ratio of 1:3; 1x10 ¹¹ vg/mL, ratio of 1:4; 1x10 ¹¹ vg/mL, ratio of 1:5; 1x10 ¹¹ vg/mL, ratio of 5:1; 1x10 ¹¹ vg/mL, ratio of 4:1; 1x10 ¹¹ vg/mL, ratio of 3:1; 1x10 ¹¹ vg/mL, ratio of 2:1; 3x10 ¹¹ vg/mL, ratio of 1:1; 2x10 ¹¹ vg/mL, ratio of 1:1; 2x10 ¹¹ vg/mL, ratio of 1:2; 2x10 ¹¹ vg/mL, ratio of 1:3; 2x10 ¹¹ vg/mL, ratio of 1:4; 2x10 ¹¹ vg/mL, ratio of 1:5; 2x10 ¹¹ vg/mL, ratio of 5:1; 2x10 ¹¹ vg/mL, ratio of 4:1; 2x10 ¹¹ vg/mL, ratio of 3:1; 2x10 ¹¹ vg/mL, ratio of 2:1; 3x10 ¹¹ vg/mL, ratio of 1:1; 3x10 ¹¹ vg/mL, ratio of 1:2; 3x10 ¹¹ vg/mL, ratio of 1:3; 3x10 ¹¹ vg/mL, ratio of 1:4; 3x10 ¹¹ vg/mL, ratio of 1:5; 3x10 ¹¹ vg/mL, ratio of 5:1; 3x10 ¹¹ vg/mL, ratio of 4:1; 3x10 ¹¹ vg/mL, ratio of 3:1; 3x10 ¹¹ vg/mL, ratio of 2:1; 4x10 ¹¹ vg/mL, ratio of 1:1; 4x10 ¹¹ vg/mL, ratio of 1:2; 4x10 ¹¹ vg/mL, ratio of 1:3; 4x10 ¹¹ vg/mL, ratio of 1:4; 4x10 ¹¹ vg/mL, ratio of 1:5; 4x10 ¹¹ vg/mL, ratio of 5:1; 4x10 ¹¹ vg/mL, ratio of 4:1; 4x10 ¹¹ vg/mL, ratio of 3:1; 4x10 ¹¹ vg/mL, ratio of 2:1; 5x10 ¹¹ vg/mL, ratio of 1:1; 5x10 ¹¹ vg/mL, ratio of 1:2; 5x10 ¹¹ vg/mL, ratio of 1:3; 5x10 ¹¹ vg/mL, ratio of 1:4; 5x10 ¹¹ vg/mL, ratio of 1:5; 5x10 ¹¹ vg/mL, ratio of 5:1; 5x10 ¹¹ vg/mL, ratio of 4:1; 5x10 ¹¹ vg/mL, ratio of 3:1; 5x10 ¹¹ vg/mL, ratio of 2:1; 6x10 ¹¹ vg/mL, ratio of 1:1; 6x10 ¹¹ vg/mL, ratio of 1:2; 6x10 ¹¹ vg/mL, ratio of 1:3; 6x10 ¹¹ vg/mL, ratio of 1:4; 6x10 ¹¹ vg/mL, ratio of 1:5; 6x10 ¹¹ vg/mL, ratio of 5:1; 6x10 ¹¹ vg/mL, ratio of 4:1; 6x10 ¹¹ vg/mL, ratio of 3:1; 6x10 ¹¹ vg/mL, ratio of 2:1; 7x10 ¹¹ vg/mL, ratio of 1:1; 7x10 ¹¹ vg/mL, ratio of 1:2; 7x10 ¹¹ vg/mL, ratio of 1:3; 7x10 ¹¹ vg/mL, ratio of 1:4; 7x10 ¹¹ vg/mL, ratio of 1:5; 7x10 ¹¹ vg/mL, ratio of 5:1; 7x10 ¹¹ vg/mL, ratio of 4:1; 7x10 ¹¹ vg/mL, ratio of 3:1; 7x10 ¹¹ vg/mL, ratio of 2:1; 8x10 ¹¹ vg/mL, ratio of 1:1; 8x10 ¹¹ vg/mL, ratio of 1:2; 8x10 ¹¹ vg/mL, ratio of 1:3; 8x10 ¹¹ vg/mL, ratio of 1:4; 8x10 ¹¹ vg/mL, ratio of 1:5; 8x10 ¹¹ vg/mL, ratio of 5:1; 8x10 ¹¹ vg/mL, ratio of 4:1; 8x10 ¹¹ vg/mL, ratio of 3:1; 8x10 ¹¹ vg/mL, ratio of 2:1; 9x10 ¹¹ vg/mL, ratio of 1:1; 9x10 ¹¹ vg/mL, ratio of 1:2; 9x10 ¹¹ vg/mL, ratio of 1:3; 9x10 ¹¹ vg/mL, ratio of 1:4; 9x10 ¹¹ vg/mL, ratio of 1:5; 9x10 ¹¹ vg/mL, ratio of 5:1; 9x10 ¹¹ vg/mL, ratio of 4:1; 9x10 ¹¹ vg/mL, ratio of 3:1; 9x10 ¹¹ vg/mL, ratio of 2:1; 1x10 ¹² vg/mL, ratio of 1:1; 1x10 ¹² vg/mL, ratio of 1:2; 1x10 ¹² vg/mL, ratio of 1:3; 1x10 ¹² vg/mL, ratio of 1:4; 1x10 ¹² vg/mL, ratio of 1:5; 1x10 ¹² vg/mL, ratio of 5:1; 1x10 ¹² vg/mL, ratio of 4:1; 1x10 ¹² vg/mL, ratio of 3:1; 1x10 ¹² vg/mL, ratio of 2:1; 2x10 ¹² vg/mL, ratio of 1:1; 2x10 ¹² vg/mL, ratio of 1:2; 2x10 ¹² vg/mL, ratio of 1:3; 2x10 ¹² vg/mL, ratio of 1:4; 2x10 ¹² vg/mL, ratio of 1:5; 2x10 ¹² vg/mL, ratio of 5:1; 2x10 ¹² vg/mL, ratio of 4:1; 2x10 ¹² vg/mL, ratio of 3:1; 2x10 ¹² vg/mL, ratio of 2:1; 3x10 ¹² vg/mL, ratio of 1:1; 3x10 ¹² vg/mL, ratio of 1:2; 3x10 ¹² vg/mL, ratio of 1:3; 3x10 ¹² vg/mL, ratio of 1:4; 3x10 ¹² vg/mL, ratio of 1:5; 3x10 ¹² vg/mL, ratio of 5:1; 3x10 ¹² vg/mL, ratio of 4:1; 3x10 ¹² vg/mL, ratio of 3:1; 3x10 ¹² vg/mL, ratio of 2:1; 4x10 ¹² vg/mL, ratio of 1:1; 4x10 ¹² vg/mL, ratio of 1:2; 4x10 ¹² vg/mL, ratio of 1:3; 4x10 ¹² vg/mL, ratio of 1:4; 4x10 ¹² vg/mL, ratio of 1:5; 4x10 ¹² vg/mL, ratio of 5:1; 4x10 ¹² vg/mL, ratio of 4:1; 4x10 ¹² vg/mL, ratio of 3:1; 4x10 ¹² vg/mL, ratio of 2:1; 5x10 ¹² vg/mL, ratio of 1:1; 5x10 ¹² vg/mL, ratio of 1:2; 5x10 ¹² vg/mL, ratio of 1:3; 5x10 ¹² vg/mL, ratio of 1:4; 5x10 ¹² vg/mL, ratio of 1:5; 5x10 ¹² vg/mL, ratio of 5:1; 5x10 ¹² vg/mL, ratio of 4:1; 5x10 ¹² vg/mL, ratio of 3:1; 5x10 ¹² vg/mL, ratio of 2:1; 6x10 ¹² vg/mL, ratio of 1:1; 6x10 ¹² vg/mL, ratio of 1:2; 6x10 ¹² vg/mL, ratio of 1:3; 6x10 ¹² vg/mL, ratio of 1:4; 6x10 ¹² vg/mL, ratio of 1:5; 6x10 ¹² vg/mL, ratio of 5:1; 6x10 ¹² vg/mL, ratio of 4:1; 6x10 ¹² vg/mL, ratio of 3:1; and 6x10 ¹² vg/mL, ratio of 2:1. In certain embodiments, the concentration of the first viral vector and the concentration of the second viral vector may be selected from the group consisting of 3.0x10 ¹¹ vg/mL (first viral vector) and 3.0x10 ¹¹ vg/mL (second viral vector) (1:1 ratio, total concentration 6x10 ¹¹ ), 2.0x10 ¹¹ vg/mL (first viral vector) and 4.0x10 ¹¹ vg/mL (second viral vector) (1:2 ratio, total concentration 6x10 ¹¹ ), 1.5x ¹¹ vg/mL (first viral vector) and 4.5x10 ¹¹ vg/mL (second viral vector) (1:3 ratio, total concentration 6x10 ¹¹ ), 1.2x10 ¹¹ vg/mL (first viral vector) and 4.8x10 ¹¹ vg/mL (second viral vector) (1:4 ratio, total concentration 6x10 ¹¹ ), 0.5x10 ¹² vg/mL (first viral vector) and 0.5x10 ¹² vg/mL (second viral vector) (1:1 ratio, total concentration 1x10 ¹² ), 0.333x10 ¹² vg/mL (first viral vector) and 0.666x10 ¹² vg/mL (second viral vector) (1:2 ratio, total concentration 1x10 ¹² ), 0.25x10 ¹² vg/mL (first viral vector) and 0.75x10 ¹² vg/mL (second viral vector) (1:3 ratio, total concentration 1x10 ¹² ), 0.2x10 ¹² vg/mL (first viral vector) and 0.8x10 ¹² vg/mL (second viral vector) (1:4 10 ratio, total concentration 1x10 ¹² ), 1.5x10 ¹² vg/mL (first viral vector) and 1.5x10 ¹² vg/mL (second viral vector) (1:1 ratio, total concentration 3x10 ¹² ), 1.0x10 ¹² vg/mL (first viral vector) and 2.0x10 ¹² vg/mL (second viral vector) (1:2 ratio, total concentration 3x10 ¹² ), 0.75x10 ¹² vg/mL (first viral vector) and 2.25x10 ¹² vg/mL (second viral vector) (1:3 ratio, total concentration 3x10 ¹² ), 0.6x10 ¹² vg/mL (first viral vector) and 2.4x10 ¹² vg/mL (second viral vector) (1:4 ratio, total concentration 3x10 ¹² ), 3.0x10 ¹² vg/mL (first viral vector) and 3.0x10 ¹² vg/mL (second viral vector) (1:1 ratio, total concentration 6x10 ¹² ), 2.0x10 ¹² vg/mL (first viral vector) and 4.0x10 ¹² vg/mL (second viral vector) (1:2 ratio, total concentration 6x10 ¹² ), 1.5x ¹² vg/mL (first viral vector) and 4.5x10 ¹² vg/mL (second viral vector) (1:3 ratio, total concentration 6x10 ¹² ), and 1.2x10 ¹² vg/mL (first viral vector) and 4.8x10 ¹² vg/mL (second viral vector) (1:4 ratio, total concentration 6x10 ¹² ). In certain embodiments, the first viral vector and second viral vector may be administered in a total volume selected from the group consisting of 1 microliter to 10 microliters, 10 microliters to 50 microliters, 50 microliters to 100 microliters, 100 microliters to 150 microliters, 150 microliters to 200 microliters, 250 microliters to 300 microliters, 300 microliters to 350 microliters, 400 microliters to 450 microliters, 500 microliters to 550 microliters, 600 microliters to 650 microliters, 700 microliters to 750 microliters, 800 microliters to 850 microliters, 900 microliters to 950 microliters, and 950 microliters to 1000 microliters. In certain embodiments, the first viral vector and second viral vector may be administered in a total volume selected from the group consisting of 50 microliters to 100 microliters, 100 microliters to 150 microliters, 150 microliters to 200 microliters, 200 microliters to 250 microliters, 250 microliters to 300 microliters, 300 microliters to 350 microliters, and 350 microliters to 400 microliters. In certain embodiments, the first viral vector and second viral vector may be administered in a total volume of 500 microliters or less, e.g., 400 microliters or less, 350 microliters or less, or 300 microliters of less.

In certain embodiments, the first viral vector and second viral vector may be administered to an eye in the subject. In certain embodiments, the first viral vector and second viral vector may be administered to a cell in the eye. In certain embodiments, the cell may be a retinal cell. In certain embodiments, the retinal cell may be a photoreceptor cell.

In certain embodiments, the method may result in from about 70% to about 100% of normalized productive editing of the RHO gene in the cell. In certain embodiments, the method may result in at least about 70%, 75%, 80%, 85%, 90%, 95%, or 100% of normalized productive editing of the RHO gene in the cell. In certain embodiments, the first viral vector and second viral vector may be administered to the subject at a total concentration of from 6.0xl0 ¹⁰ vg/mL to 6.0xl0 ¹² vg/mL (e.g., l.OxlO ¹¹ vg/mL to 3.0xl0 ¹² vg/mL) and the method results in at least about 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100% of normalized productive editing of the RHO gene in the cell. In certain embodiments, the method may result in from about 10% to about 100%, from about 20% to about 100%, from about 30% to about 100%, from about 40% to about 100%, from about 50% to about 100%, from about 50% to about 100%, from about 60% to about 100%, from about 70% to about 100%, from about 80% to about 100%, from about 90% to about 100% of normalized productive editing of the RHO gene in the cell. In certain embodiments, the method may result in at least about 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100% of normalized productive editing of the RHO gene in the cell. In certain embodiments, the editing may be analyzed using Uni- Directional Targeted Sequencing (UDiTaS).

In certain embodiments, the method may result in a statistically significant reduction of a level of endogenous RHO messenger RNA (mRNA) in the cell compared to a level of endogenous RHO mRNA in a cell that was not treated with the first and second viral vectors. In certain embodiments, the method may result in from about 50% to about 100% (e.g., about 70% to about 100%) reduction of a level of endogenous RHO mRNA in the cell compared to a level of endogenous RHO mRNA in a cell that was not treated with the first and second viral vectors. In certain embodiments, the method may result in an at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100% reduction of a level of endogenous RHO mRNA in the cell compared to a level of endogenous RHO mRNA in a cell that was not treated with the first and second viral vectors. In certain embodiments, the first viral vector and second viral vector may be administered to the subject at a total concentration of from 6.0xl0 ¹⁰ vg/mL to 6.0xl0 ¹² vg/mL (e.g., l.OxlO ¹¹ vg/mL to 3.0xl0 ¹² vg/mL) and the method may result in an at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%,

100% reduction of a level of endogenous RHO mRNA in the cell compared to a level of endogenous RHO mRNA in a cell that was not treated with the first and second viral vectors. In certain embodiments, the method may result in an at least about 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100% reduction of a level of endogenous RHO mRNA in the cell compared to a level of endogenous RHO mRNA in a cell that was not treated with the first and second viral vectors. In certain embodiments, the method may result in 20% to 25%, 25% to 30%, 30% to 35%, 35% to 40%, 40% to 45%, 45% to 50%, 50% to 55%, 55% to 60%, 60% to 65%, 65% to 70%, 70% to 75%, 75% to 80%, 80% to 85%, 85% to 90%, 90% to 95%, or 95% to 100% or more reduction of a level of endogenous RHO mRNA in the cell compared to a level of endogenous RHO mRNA in a cell that was not treated with the first and second viral vectors. In certain embodiments, a level of mRNA may be measured using NanoString technology.

In certain embodiments, the method may result in from about 50% to about 100%

(e.g., about 70% to about 100%) reduction of a level of endogenous RHO protein in the cell compared to a level of endogenous RHO protein in a cell that was not treated with the first and second viral vectors. In certain embodiments, the method may result in an at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100% reduction of a level of endogenous RHO protein in the cell compared to a level of endogenous RHO protein in a cell that was not treated with the first and second viral vectors. In certain embodiments, the first viral vector and second viral vector may be administered to the subject at a total concentration of from 6.0xl0 ¹⁰ vg/mL to 6.0xl0 ¹² vg/mL (e.g., l.OxlO ¹ vg/mL to 3.0xl0 ¹² vg/mL) and the method results in an at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100% reduction of a level of endogenous RHO protein in the cell compared to a level of endogenous RHO protein in a cell that was not treated with the first and second viral vectors. In certain embodiments, the first viral vector and second viral vector may be administered to the subject at a total concentration of from 3.0xl0 ¹² vg/mL to 6.0xl0 ¹² vg/mL and the method results in an at least about 40%, 45%, 50%, 55%, 60%, 65%, 90%, 95%,

100% reduction of a level of endogenous RHO protein in the cell compared to a level of endogenous RHO protein in a cell that was not treated with the first and second viral vectors. In certain embodiments, the method may result in at least about 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100% reduction of a level of endogenous RHO protein in the cell compared to a level of endogenous RHO protein in a cell that was not treated with the first and second viral vectors. In certain embodiments, the method may result in an about 50% to 55%, 55% to 60%, 60% to 65%, 65% to 70%, 70% to 75%, 75% to 80%, 80% to 85%, 85% to 90%, 90% to 95%, or 95% to 100% reduction of a level of endogenous RHO protein in the cell compared to a level of endogenous RHO protein in a cell that was not treated with the first and second viral vectors. In certain embodiments, a level of endogenous RHO protein may be measured using tandem mass spectrometry. In certain embodiments, the method may result in an increase of at least about 10%, 15%, 20%, 25%, 30%, 35% of exogenous RHO mRNA in the cell compared to exogenous RHO mRNA in a cell that was not treated with the first and second viral vectors. In certain embodiments, the method may result in an increase of at least about 30% of exogenous RHO mRNA in the cell compared to exogenous RHO mRNA in a cell that was not treated with the first and second viral vectors. In certain embodiments, the first viral vector and second viral vector may be administered to the subject at a total concentration of from 6.0x10 ¹⁰ vg/mL to 6.0x10 ¹² vg/mL (e.g., 1.0x10 ¹¹ vg/mL to 3.0x10 ¹² vg/mL) and the method may result in an increase of at least about 10%, 15%, 20%, 25%, 30%, 35% of exogenous RHO mRNA in the cell compared to exogenous RHO mRNA in a cell that was not treated with the first and second viral vectors. In certain embodiments, the first viral vector and second viral vector may be administered to the subject at a total concentration of from 6.0x10 ¹⁰ vg/mL to 6.0x10 ¹² vg/mL, 1.0x10 ¹¹ vg/mL to 3.0x10 ¹² vg/mL, or 3.0x10 ¹¹ vg/mL to 1.0x10 ¹² vg/mL and the method may result in an increase of at least about 10%, 15%, 20%, 25%, 30%, 35% of exogenous RHO mRNA in the cell compared to exogenous RHO mRNA in a cell that was not treated with the first and second viral vectors. In certain embodiments, the method may result in an increase of at least about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55% of exogenous RHO mRNA in the cell compared to exogenous RHO mRNA in a cell that was not treated with the first and second viral vectors. In certain embodiments, the method may result in at least about 1% to 5%, 5% to 10%, 10% to 15%, 15% to 20%, 20% to 25%, 25% to 30%, 30% to 35%, 35% to 40%, 40% to 45%, 45% to 50% of exogenous RHO mRNA in the cell compared to exogenous RHO mRNA in a cell that was not treated with the first and second viral vectors. In certain embodiments, the exogenous RHO mRNA may be analyzed using NanoString technology. 1 In certain embodiments, the method may result in a therapeutically effective amount of exogenous RHO protein in the cell compared to exogenous RHO protein in a cell that was not treated with the first and second viral vectors. In certain embodiments, the method may result in an increase of at least about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60% of exogenous RHO protein in the cell compared to exogenous RHO protein in a cell that was not treated with the first and second viral vectors. In certain embodiments, the method may result in an increase of at least about 5% to 10%, 10%, to 15%, 15% to 20%,

20% to 25%, 25% to 30%, 30% to 35%, 35% to 40%, 40% to 45%, 45% to 50%, 50% to 55%, 55% to 60% of exogenous RHO protein in the cell compared to exogenous RHO protein in a cell that was not treated with the first and second viral vectors. In certain embodiments, the first viral vector and second viral vector may be administered to the subject at a total concentration of from 6.0xl0 ¹² vg/mL to 6.0xl0 ¹² vg/mL and (e.g., l.OxlO ¹¹ vg/mL to 3.0xl0 ¹² vg/mL); and the method may result in an increase of at least about 5%, 10%,

15%, 20%, 25%, 30%, 35% of exogenous RHO protein in the cell compared to exogenous RHO protein in the cell compared to exogenous RHO protein in a cell that was not treated with the first and second viral vectors. In certain embodiments, the exogenous RHO protein may be analyzed using tandem mass spectrometry.

In certain embodiments, the method may result in a production of < 5%, < 6%, < 7%, < 8%, < 9%, < 10%, < 11% in frame-indels in the RHO gene. In certain embodiments, the method may result in a frameshift in the RHO gene.

In certain embodiments, the cell may be a retinal cell. In certain embodiments, the retinal cell may be a photoreceptor cell.

In certain embodiments, the first viral vector, the second viral vector, or the first viral vector and second viral vector may be selected from the group consisting of an AAV vector, an adenovirus vector, a vaccinia vims vector, and a herpes simplex virus vector. In certain embodiments, the AAV vector may be an AAV5 vector. In certain embodiments, the first nucleotide sequence may be a first AAV5 vector. In certain embodiments, the second nucleotide sequence may be a second AAV5 vector.

In certain embodiments, the compositions disclosed herein may be for the use in therapy.

Provided herein in certain aspects are methods for altering a cell comprising contacting the cell with the compositions disclosed herein and wherein the method results in a reduction of endogenous RHO protein compared to endogenous RHO protein in a cell that was not contacted with the composition; and wherein the method results in an increase of exogenous RHO protein in the cell compared to exogenous RHO protein in a cell that was not treated with the first and second viral vectors. In certain embodiments, the method may result in from about 50% to about 100% (e.g., about 70% to about 100%) reduction of a level of endogenous RHO protein in the cell compared to a level of endogenous RHO protein in a cell that was not treated with the first and second viral vectors. In certain embodiments, the method may result in an at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100% reduction of a level of endogenous RHO protein in the cell compared to a level of endogenous RHO protein in a cell that was not treated with the first and second viral vectors. In certain embodiments, the first viral vector and second viral vector may be administered to the subject at a total concentration of from 6.0xl0 ¹⁰ vg/mL to 6.0xl0 ¹² vg/mL (e.g., l.OxlO ¹ vg/mL to 3.0xl0 ¹² vg/mL) and the method may result in an at least about 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100% reduction of a level of endogenous RHO protein in the cell compared to a level of endogenous RHO protein in a cell that was not treated with the first and second viral vectors. In certain embodiments, the method may result in an at least about 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%,

75%, 80%, 85%, 90%, 95%, 100% reduction of a level of endogenous RHO protein in the cell compared to a level of endogenous RHO protein in a cell that was not treated with the first and second viral vectors. In certain embodiments, the method may result in an about 50% to 55%, 55% to 60%, 60% to 65%, 65% to 70%, 70% to 75%, 75% to 80%, 80% to 85%, 85% to 90%, 90% to 95%, or 95% to 100% reduction of a level of endogenous RHO protein in the cell compared to a level of endogenous RHO protein in a cell that was not treated with the first and second viral vectors. In certain embodiments, the level of endogenous RHO protein may be analyzed using tandem mass spectrometry. In certain embodiments, the method may result in a therapeutically effective amount of exogenous RHO protein in the cell compared to exogenous RHO protein in a cell that was not treated with the first and second viral vectors.

In certain embodiments, the method may result in an increase of at least about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55% of exogenous RHO protein in the cell compared to exogenous RHO mRNA in a cell that was not treated with the first and second viral vectors. In certain embodiments, the method may result in an increase of at least about 5% to 10%, 10%, to 15%, 15% to 20%, 20% to 25%, 25% to 30%, 30% to 35%, 35% to 40%, 40% to 45%, 45% to 50%, 50% to 55%, 55% to 60% of exogenous RHO protein in the cell compared to exogenous RHO protein in a cell that was not treated with the first and second viral vectors. In certain embodiments, the first viral vector and second viral vector may be administered to the subject at a total concentration of from 6.0xl0 ¹² vg/mL to 6.0xl0 ¹² vg/mL and (e.g., l.OxlO ¹¹ vg/mL to 3.0xl0 ¹² vg/mL) and the method may result in an increase of at least about 5%, 10%, 15%, 20%, 25%, 30%, 35% of exogenous RHO protein in the cell compared to exogenous RHO protein in the cell compared to exogenous RHO protein in a cell that was not treated with the first and second viral vectors. In certain embodiments, the exogenous RHO protein may be analyzed using tandem mass spectrometry.

In certain embodiments, the cell may be a retinal cell. In certain embodiments, the retinal cell may be a photoreceptor cell. In certain embodiments, the first viral vector, the second viral vector, or the first viral vector and second viral vector are selected from the group consisting of an AAV vector, an adenovirus vector, a vaccinia virus vector, and a herpes simplex virus vector. In certain embodiments, the AAV vector may be an AAV5 vector. In certain embodiments, the first nucleotide sequence may be a first AAV5 vector. In certain embodiments, the second nucleotide sequence may be a second AAV5 vector.

In certain embodiments, the 5’ UTR region (e.g., 5’ UTR, exon 1, exon 2, intron 1, exon 1/intron 1, or exon 2/intron 1 border) of a mutant RHO gene, is targeted to alter (i.e., knockout (e.g., eliminate expression of)) the mutant RHO gene.

The RHO gene encodes the rhodopsin protein and is expressed in retinal photoreceptor (PR) rod cells. Rhodopsin is a G protein-coupled receptor expressed in the outer segment of rod cells and is a critical element of the phototransduction cascade. Defects in the RHO gene are typically characterized by decreased production of wild-type rhodopsin and/or expression of mutant rhodopsin which lead to interruptions in photoreceptor function and corresponding vision loss. Mutations in RHO typically result in degeneration of PR rod cells first, followed by degeneration of PR cone cells as the disease progresses. Subjects with RHO mutations experience progressive loss of night vision, as well as loss of peripheral visual fields followed by loss of central visual fields. Exemplary RHO mutations are provided in Table A. In some embodiments, the compositions and methods described herein can be used to treat subject having any RHO mutation (e.g., in Table A) that causes a disease phenotype.

Some aspects of the present disclosure provide strategies, methods, compositions, and treatment modalities for altering a RHO gene sequence, e.g., altering the sequence of a wild type and/or of a mutant RHO gene, e.g., in a cell or in a patient having adRP, by insertion or deletion of one or more nucleotides mediated by an RNA-guided nuclease (e.g., Cas9 or Cpfl molecule) and one or more guide RNAs (gRNAs), resulting in loss of function of the RHO gene sequence. This type of alteration is also referred to as “knocking out” the RHO gene. Some aspects of the present disclosure provide strategies, methods, compositions, and treatment modalities for expressing exogenous RHO, e.g., in a cell subjected to an RNA- guided nuclease-mediated knock-out of RHO, e.g., by delivering an exogenous RHO complementary DNA (cDNA) sequence encoding a functional rhodopsin protein (e.g., a wild- type rhodopsin protein).

In certain embodiments, a 5’ region of the RHO gene (e.g., 5’ untranslated region (UTR), exon 1, exon 2, intron 1, the exon 1/intron 1 border or the exon 2/intron 1 border) is targeted by an RNA-guided nuclease to alter the gene. In certain embodiments, any region of the RHO gene (e.g., a promoter region, a 5 ’untranslated region, a 3’ untranslated region, an exon, an intron, or an exon/intron border) is targeted by an RNA-guided nuclease to alter the gene. In certain embodiments, a non-coding region of the RHO gene (e.g., an enhancer region, a promoter region, an intron, 5’ UTR, 3 ’UTR, polyadenylation signal) is targeted to alter the gene. In certain embodiments, a coding region of the RHO gene (e.g., early coding region, an exon) is targeted to alter the gene. In certain embodiments, a region spanning an exon/intron border of the RHO gene (e.g., exon 1/intron 1, exon 2/intron 1) is targeted to alter the gene. In certain embodiments, a region of the RHO gene is targeted which, when altered, results in a stop codon and knocking out the RHO gene. In certain embodiments, alteration of the mutant RHO gene occurs in a mutation-independent manner, which provides the benefit of circumventing the need to develop therapeutic strategies for each RHO mutation set forth in Table A.

In an embodiment, after treatment, one or more symptoms associated with adRP (e.g., nyctalopia, abnormal electroretinogram, cataract, visual field defect, rod-cone dystrophy, or other symptom(s) known to be associated with adRP) is ameliorated, e.g., progression of adRP is delayed, inhibited, prevented or halted, PR cell degeneration is delayed, inhibited, prevented and/or halted, and/or visual loss is ameliorated, e.g., progression of visual loss is delayed, inhibited, prevented, or halted. In an embodiment, after treatment, progression of adRP is delayed, e.g., PR cell degeneration is delayed. In an embodiment, after treatment, progression of adRP is reversed, e.g., function of existing PR rod cells and cone cells and/or birth of new PR rod cells and cone cells is increased/enhanced and/or visual loss e.g., progression of visual loss is delayed, inhibited, prevented, or halted.

In an embodiment, CRISPR/RNA-guided nuclease-related methods and components and compositions of the disclosure provide for the alteration (e.g., knocking out) of a mutant RHO gene associated with adRP, by altering the sequence at a RHO target position, e.g., by creating an indel resulting in loss-of-function of the affected RHO gene or allele, e.g., a nucleotide substitution resulting in a truncation, nonsense mutation, or other type of loss-of- function of an encoded RHO gene product, e.g., of the encoded RHO mRNA or RHO protein; a deletion of one or more nucleotides resulting in a truncation, nonsense mutation, or other type of loss-of-function of an encoded RHO gene product, e.g., of the encoded RHO mRNA or RHO protein, e.g., a single nucleotide, double nucleotide, or other frame- shifting deletion, or a deletion resulting in a premature stop codon; or an insertion resulting in a truncation, nonsense mutation, or other type of loss-of-function of an encoded RHO gene product, e.g., of the encoded RHO mRNA or RHO protein e.g., a single nucleotide, double nucleotide, or other frame- shifting insertion, or an insertion resulting in a premature stop codon. In some embodiments, CRISPR/RNA-guided nuclease-related methods and components and compositions of the disclosure provide for the alteration (e.g., knocking out) of a mutant RHO gene associated with adRP, by altering the sequence at a RHO target position, e.g., creating an indel that results in nonsense-mediated decay of an encoded gene product, e.g., an encoded RHO transcript.

In one aspect, disclosed herein is a gRNA molecule, e.g., an isolated or non-naturally occurring gRNA molecule, comprising a targeting domain which is complementary with a target domain from the RHO gene.

In an embodiment, the targeting domain of the gRNA molecule is configured to provide a cleavage event, e.g., a double strand break or a single strand break, sufficiently close to an RHO target position, in the RHO gene to allow alteration in the RHO gene, resulting in disruption (e.g., knocking out) of the RHO gene activity, e.g., a loss-of-function of the RHO gene, for example, characterized by reduced or abolished expression of a RHO gene product (e.g., a RHO transcript or a RHO protein), or by expression of a dysfunctional or non-functional RHO gene product (e.g., a truncated RHO protein or transcript). In an embodiment, the targeting domain is configured such that a cleavage event, e.g., a double strand or single strand break, is positioned within 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 150 or 200 nucleotides of an RHO target position. The break, e.g., a double strand or single strand break, can be positioned upstream or downstream of an RHO target position, in the RHO gene.

In an embodiment, a second gRNA molecule comprising a second targeting domain is configured to provide a cleavage event, e.g., a double strand break or a single strand break, sufficiently close to the RHO target position, in the RHO gene, to allow alteration in the RHO gene, either alone or in combination with the break positioned by said first gRNA molecule. In an embodiment, the targeting domains of the first and second gRNA molecules are configured such that a cleavage event, e.g., a double strand or single strand break, is positioned, independently for each of the gRNA molecules, within 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 150 or 200 nucleotides of the target position. In an embodiment, the breaks, e.g., double strand or single strand breaks, are positioned on both sides of a nucleotide of a RHO target position, in the RHO gene. In an embodiment, the breaks, e.g., double strand or single strand breaks, are positioned on one side, e.g., upstream or downstream, of a nucleotide of a RHO target position, in the RHO gene.

In an embodiment, a single strand break is accompanied by an additional single strand break, positioned by a second gRNA molecule, as discussed below. For example, the targeting domains are configured such that a cleavage event, e.g., the two single strand breaks, are positioned within 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 150 or 200 nucleotides of a RHO target position. In an embodiment, the first and second gRNA molecules are configured such, that when guiding a Cas9 nickase, a single strand break will be accompanied by an additional single strand break, positioned by a second gRNA, sufficiently close to one another to result in alteration of a RHO target position, in the RHO gene. In an embodiment, the first and second gRNA molecules are configured such that a single strand break positioned by said second gRNA is within 10, 20, 30, 40, or 50 nucleotides of the break positioned by said first gRNA molecule, e.g., when the Cas9 is a nickase. In an embodiment, the two gRNA molecules are configured to position cuts at the same position, or within a few nucleotides of one another, on different strands, e.g., essentially mimicking a double strand break.

In an embodiment, a double strand break can be accompanied by an additional double strand break, positioned by a second gRNA molecule, as is discussed below. For example, the targeting domain of a first gRNA molecule is configured such that a double strand break is positioned upstream of a RHO target position, in the RHO gene, e.g., within 1, 2, 3, 4, 5,

10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 150 or 200 nucleotides of the target position; and the targeting domain of a second gRNA molecule is configured such that a double strand break is positioned downstream of a RHO target position, in the RHO gene, e.g., within 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 150 or 200 nucleotides of the target position.

In an embodiment, a double strand break can be accompanied by two additional single strand breaks, positioned by a second gRNA molecule and a third gRNA molecule. For example, the targeting domain of a first gRNA molecule is configured such that a double strand break is positioned upstream of a RHO target position, in the RHO gene, e.g., within 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 150 or 200 nucleotides of the target position; and the targeting domains of a second and third gRNA molecule are configured such that two single strand breaks are positioned downstream of a RHO target position, in the RHO gene, e.g., within 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 150 or 200 nucleotides of the target position. In an embodiment, the targeting domain of the first, second and third gRNA molecules are configured such that a cleavage event, e.g., a double strand or single strand break, is positioned, independently for each of the gRNA molecules.

In an embodiment, a first and second single strand breaks can be accompanied by two additional single strand breaks positioned by a third gRNA molecule and a fourth gRNA molecule. For example, the targeting domain of a first and second gRNA molecule are configured such that two single strand breaks are positioned upstream of a RHO target position, in the RHO gene, e.g., within 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 150 or 200 nucleotides of the target position; and the targeting domains of a third and fourth gRNA molecule are configured such that two single strand breaks are positioned downstream of a RHO target position, in the RHO gene, e.g., within 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 150 or 200 nucleotides of the target position.

It is contemplated herein that when multiple gRNAs are used to generate (1) two single stranded breaks in close proximity (2) one double stranded break and two paired nicks flanking a RHO target position (e.g., to remove a piece of DNA) or (3) four single stranded breaks, two on each side of a RHO target position, that they are targeting the same RHO target position. It is further contemplated herein that multiple gRNAs may be used to target more than one RHO target position in the same gene.

In some embodiments, the targeting domain of the first gRNA molecule and the targeting domain of the second gRNA molecules are complementary to opposite strands of the target nucleic acid molecule. In some embodiments, the gRNA molecule and the second gRNA molecule are configured such that the PAMs are oriented outward.

In an embodiment, the targeting domain of a gRNA molecule is configured to avoid unwanted target chromosome elements, such as repeat elements, e.g., Alu repeats, in the target domain. The gRNA molecule may be a first, second, third and/or fourth gRNA molecule.

In an embodiment, the RHO target position is a target position located in exon 1 or exon 2 of the RHO gene and the targeting domain of a gRNA molecule comprises a sequence that is the same as, or differs by no more than 1, 2, 3, 4, or 5 nucleotides from, a targeting domain sequence from Table 1. In some embodiments, the targeting domain is selected from those in Table 1. In an embodiment, the RHO target position is a target position located in the 5’ UTR region of the RHO gene and the targeting domain of a gRNA molecule comprises a sequence that is the same as, or differs by no more than 1, 2, 3, 4, or 5 nucleotides from, a targeting domain sequence from any one of Table 2. In some embodiments, the targeting domain is selected from those in Table 2. In an embodiment, the target position is a target position located in intron 1 of the RHO gene and the targeting domain of a gRNA molecule comprises a sequence that is the same as, or differs by no more than 1, 2, 3, 4, or 5 nucleotides from, a targeting domain sequence from any one of Table 3. In some embodiments, the targeting domain is selected from those in Table 3. In an embodiment, the target position is a target position located in the RHO gene and the targeting domain of a gRNA molecule comprises a sequence that is the same as, or differs by no more than 1, 2, 3, 4, or 5 nucleotides from, a targeting domain sequence from any one of Table 18. In some embodiments, the targeting domain is selected from those in Table 18. In an embodiment, the gRNA, e.g., a gRNA comprising a targeting domain, which is complementary with the RHO gene, is a modular gRNA. In other embodiments, the gRNA is a unimolecular or chimeric gRNA.

In an embodiment, the targeting domain which is complementary with the RHO gene is 17 nucleotides or more in length. In an embodiment, the targeting domain is 17 nucleotides in length. In other embodiments, the targeting domain is 18 nucleotides in length. In still other embodiments, the targeting domain is 19 nucleotides in length. In still other embodiments, the targeting domain is 20 nucleotides in length. In still other embodiments, the targeting domain is 21 nucleotides in length. In still other embodiments, the targeting domain is 22 nucleotides in length. In still other embodiments, the targeting domain is 23 nucleotides in length. In still other embodiments, the targeting domain is 24 nucleotides in length. In still other embodiments, the targeting domain is 25 nucleotides in length. In still other embodiments, the targeting domain is 26 nucleotides in length.

A gRNA as described herein may comprise from 5’ to 3’ : a targeting domain (comprising a “core domain”, and optionally a “secondary domain”); a first complementarity domain; a linking domain; a second complementarity domain; a proximal domain; and a tail domain. In some embodiments, the proximal domain and tail domain are taken together as a single domain. In an embodiment, a gRNA comprises a linking domain of no more than 25 nucleotides in length; a proximal and tail domain, that taken together, are at least 20 nucleotides in length; and a targeting domain of 17, 18, 19 or 20 nucleotides in length.

In another embodiment, a gRNA comprises a linking domain of no more than 25 nucleotides in length; a proximal and tail domain, that taken together, are at least 30 nucleotides in length; and a targeting domain of 17, 18, 19 or 20 nucleotides in length.

In another embodiment, a gRNA comprises a linking domain of no more than 25 nucleotides in length; a proximal and tail domain, that taken together, are at least 30 nucleotides in length; and a targeting domain of 17, 18, 19 or 20 nucleotides in length.

In another embodiment, a gRNA comprises a linking domain of no more than 25 nucleotides in length; a proximal and tail domain, that taken together, are at least 40 nucleotides in length; and a targeting domain of 17, 18, 19 or 20 nucleotides in length.

A cleavage event, e.g., a double strand or single strand break, is generated by an RNA-guided nuclease (e.g., a Cas9 or Cpfl molecule). The Cas9 molecule may be an enzymatically active Cas9 (eaCas9) molecule, e.g., an eaCas9 molecule that forms a double strand break in a target nucleic acid or an eaCas9 molecule forms a single strand break in a target nucleic acid (e.g., a nickase molecule). In certain embodiments, the RNA-guided nuclease may be a Cpfl molecule.

In some embodiments, the RNA-guided nuclease (e.g., eaCas9 molecule or Cpfl molecule) catalyzes a double strand break.

In some embodiments, the eaCas9 molecule comprises HNH-like domain cleavage activity but has no, or no significant, N-terminal RuvC-like domain cleavage activity. In this case, the eaCas9 molecule is an HNH-like domain nickase, e.g., the eaCas9 molecule comprises a mutation at D10, e.g., D10A. In other embodiments, the eaCas9 molecule comprises N-terminal RuvC-like domain cleavage activity but has no, or no significant, HNH-like domain cleavage activity. In this instance, the eaCas9 molecule is an N-terminal RuvC-like domain nickase, e.g., the eaCas9 molecule comprises a mutation at H840, e.g., H840A.

In certain embodiments, the Cas9 molecule may be a self-inactivating Cas9 molecule designed for transient expression of the Cas9 protein.

In an embodiment, a single strand break is formed in the strand of the target nucleic acid to which the targeting domain of said gRNA is complementary. In another embodiment, a single strand break is formed in the strand of the target nucleic acid other than the strand to which the targeting domain of said gRNA is complementary. In another aspect, disclosed herein is a nucleic acid, e.g., an isolated or non-naturally occurring nucleic acid, e.g., DNA, that comprises (a) a sequence that encodes a gRNA molecule comprising a targeting domain, as disclosed herein.

In an embodiment, the nucleic acid encodes a gRNA molecule, e.g., a first gRNA molecule, comprising a targeting domain configured to provide a cleavage event, e.g., a double strand break or a single strand break, sufficiently close to a RHO target position, in the RHO gene to allow alteration in the RHO gene. In an embodiment, the nucleic acid encodes a gRNA molecule, e.g., the first gRNA molecule, comprising a targeting domain comprising a sequence that is the same as, or differs by no more than 1, 2, 3, 4, or 5 nucleotides from, a targeting domain sequence selected from those set forth in Tables 1-3 and 18. In an embodiment, the nucleic acid encodes a gRNA molecule comprising a targeting domain sequence selected from those set forth in Tables 1-3 and 18.

In an embodiment, the nucleic acid encodes a modular gRNA, e.g., one or more nucleic acids encode a modular gRNA. In other embodiments, the nucleic acid encodes a chimeric gRNA. The nucleic acid may encode a gRNA, e.g., the first gRNA molecule, comprising a targeting domain comprising 17 nucleotides or more in length. In one embodiment, the nucleic acid encodes a gRNA, e.g., the first gRNA molecule, comprising a targeting domain that is 17 nucleotides in length. In other embodiments, the nucleic acid encodes a gRNA, e.g., the first gRNA molecule, comprising a targeting domain that is 18 nucleotides in length. In still other embodiments, the nucleic acid encodes a gRNA, e.g., the first gRNA molecule, comprising a targeting domain that is 19 nucleotides in length. In still other embodiments, the nucleic acid encodes a gRNA, e.g., the first gRNA molecule, comprising a targeting domain that is 20 nucleotides in length.

In an embodiment, a nucleic acid encodes a gRNA comprising from 5’ to 3’ : a targeting domain (comprising a “core domain”, and optionally a “secondary domain”); a first complementarity domain; a linking domain; a second complementarity domain; a proximal domain; and a tail domain. In some embodiments, the proximal domain and tail domain are taken together as a single domain.

In an embodiment, a nucleic acid encodes a gRNA e.g., the first gRNA molecule, comprising a linking domain of no more than 25 nucleotides in length; a proximal and tail domain, that taken together, are at least 20 nucleotides in length; and a targeting domain of 17, 18, 19 or 20 nucleotides in length.

In an embodiment, a nucleic acid encodes a gRNA e.g., the first gRNA molecule, comprising a linking domain of no more than 25 nucleotides in length; a proximal and tail domain, that taken together, are at least 30 nucleotides in length; and a targeting domain of 17, 18, 19 or 20 nucleotides in length.

In an embodiment, a nucleic acid encodes a gRNA e.g., the first gRNA molecule, comprising a linking domain of no more than 25 nucleotides in length; a proximal and tail domain, that taken together, are at least 30 nucleotides in length; and a targeting domain of 17, 18, 19 or 20 nucleotides in length.

In an embodiment, a nucleic acid encodes a gRNA comprising e.g., the first gRNA molecule, a linking domain of no more than 25 nucleotides in length; a proximal and tail domain, that taken together, are at least 40 nucleotides in length; and a targeting domain of 17, 18, 19 or 20 nucleotides in length.

In an embodiment, a nucleic acid comprises (a) a sequence that encodes a gRNA molecule e.g., the first gRNA molecule, comprising a targeting domain that is complementary with a RHO target domain in the RHO gene as disclosed herein, and further comprising (b) a sequence that encodes an RN A- guided nuclease (e.g., Cas9 or Cpfl molecule).

The Cas9 molecule may be an enzymatically active Cas9 (eaCas9) molecule, e.g., an eaCas9 molecule that forms a double strand break in a target nucleic acid or an eaCas9 molecule forms a single strand break in a target nucleic acid (e.g., a nickase molecule).

A nucleic acid disclosed herein may comprise (a) a sequence that encodes a gRNA molecule comprising a targeting domain that is complementary with a RHO target domain in the RHO gene as disclosed herein; (b) a sequence that encodes an RNA-guided nuclease (e.g., Cas9 or Cpfl molecule); (c) a RHO cDNA molecule; and further comprises (d)(i) a sequence that encodes a second gRNA molecule described herein having a targeting domain that is complementary to a second target domain of the RHO gene, and optionally, (ii) a sequence that encodes a third gRNA molecule described herein having a targeting domain that is complementary to a third target domain of the RHO gene; and optionally, (iii) a sequence that encodes a fourth gRNA molecule described herein having a targeting domain that is complementary to a fourth target domain of the RHO gene.

In an embodiment, the RHO cDNA molecule is a double stranded nucleic acid. In some embodiments, the RHO cDNA molecule comprises a nucleotide sequence, e.g., of one or more nucleotides, encoding rhodopsin protein. In certain embodiments, the RHO cDNA molecule is not codon modified. In certain embodiments, the RHO cDNA molecule is codon modified to provide resistance to hybridization with a gRNA molecule. In certain embodiments, the RHO cDNA molecule is codon modified to provide improved expression of the encoded RHO protein (e.g., SEQ ID NOs:13-18). In certain embodiments, the RHO cDNA molecule may include a nucleotide sequence comprising exon 1, exon 2, exon 3, exon 4, and exon 5 of the RHO gene. In certain embodiments, the RHO cDNA may include an intron (e.g., SEQ ID NOs:4-7). In certain embodiments, the RHO cDNA molecule may include a nucleotide sequence comprising exon 1, intron 1, exon 2, exon 3, exon 4, and exon 5 of the RHO gene. In certain embodiments, the RHO cDNA molecule may include one or more of a nucleotide sequence comprising or consisting of the sequences selected from exon 1, intron 1, exon 2, intron 2, exon 3, intron 3, exon 4, intron 4, and exon 5 of the RHO gene. In certain embodiments, the intron comprises one or more truncations at a 5’ end of intron 1, a 3 ’ end of intron 1 , or both.

In an embodiment, a nucleic acid encodes a second gRNA molecule comprising a targeting domain configured to provide a cleavage event, e.g., a double strand break or a single strand break, sufficiently close to a RHO target position, in the RHO gene, to allow alteration in the RHO gene, either alone or in combination with the break positioned by said first gRNA molecule.

In an embodiment, a nucleic acid encodes a third gRNA molecule comprising a targeting domain configured to provide a cleavage event, e.g., a double strand break or a single strand break, sufficiently close to a RHO target position, in the RHO gene to allow alteration in the RHO gene, either alone or in combination with the break positioned by the first and/or second gRNA molecule.

In an embodiment, a nucleic acid encodes a fourth gRNA molecule comprising a targeting domain configured to provide a cleavage event, e.g., a double strand break or a single strand break, sufficiently close to a RHO target position, in the RHO gene to allow alteration either alone or in combination with the break positioned by the first gRNA molecule, the second gRNA molecule and the third gRNA molecule.

In an embodiment, the nucleic acid encodes a second gRNA molecule. The second gRNA is selected to target the same RHO target position, as the first gRNA molecule. Optionally, the nucleic acid may encode a third gRNA, and further optionally, the nucleic acid may encode a fourth gRNA molecule. The third gRNA molecule and the fourth gRNA molecule are selected to target the same RHO target position, as the first and second gRNA molecules.

In an embodiment, the nucleic acid encodes a second gRNA molecule comprising a targeting domain comprising a sequence that is the same as, or differs by no more than 1, 2, 3, 4, or 5 nucleotides from, a targeting domain sequence selected from those set forth in Tables 1-3 and 18. In an embodiment, the nucleic acid encodes a second gRNA molecule comprising a targeting domain selected from those set forth in Tables 1-3 and 18. In an embodiment, when a third or fourth gRNA molecule are present, the third and fourth gRNA molecules may independently comprise a targeting domain comprising a sequence that is the same as, or differs by no more than 1, 2, 3, 4, or 5 nucleotides from, a targeting domain sequence selected from those set forth in Tables 1-3 and 18. In a further embodiment, when a third or fourth gRNA molecule are present, the third and fourth gRNA molecules may independently comprise a targeting domain selected from those set forth in Tables 1-3 and 18.

In an embodiment, the nucleic acid encodes a second gRNA which is a modular gRNA, e.g., wherein one or more nucleic acid molecules encode a modular gRNA. In other embodiments, the nucleic acid encoding a second gRNA is a chimeric gRNA. In other embodiments, when a nucleic acid encodes a third or fourth gRNA, the third and fourth gRNA may be a modular gRNA or a chimeric gRNA. When multiple gRNAs are used, any combination of modular or chimeric gRNAs may be used.

A nucleic acid may encode a second, a third, and/or a fourth gRNA comprising a targeting domain comprising 17 nucleotides or more in length. In an embodiment, the nucleic acid encodes a second gRNA comprising a targeting domain that is 17 nucleotides in length. In other embodiments, the nucleic acid encodes a second gRNA comprising a targeting domain that is 18 nucleotides in length. In still other embodiments, the nucleic acid encodes a second gRNA comprising a targeting domain that is 19 nucleotides in length. In still other embodiments, the nucleic acid encodes a second gRNA comprising a targeting domain that is 20 nucleotides in length.

In an embodiment, a nucleic acid encodes a second, a third, and/or a fourth gRNA comprising from 5’ to 3’: a targeting domain; a first complementarity domain; a linking domain; a second complementarity domain; a proximal domain; and a tail domain. In some embodiments, the proximal domain and tail domain are taken together as a single domain.

In an embodiment, a nucleic acid encodes a second, a third, and/or a fourth gRNA comprising a linking domain of no more than 25 nucleotides in length; a proximal and tail domain, that taken together, are at least 20 nucleotides in length; and a targeting domain of 17, 18, 19 or 20 nucleotides in length.

In an embodiment, a nucleic acid encodes a second, a third, and/or a fourth gRNA comprising a linking domain of no more than 25 nucleotides in length; a proximal and tail domain, that taken together, are at least 30 nucleotides in length; and a targeting domain of 17, 18, 19 or 20 nucleotides in length. In an embodiment, a nucleic acid encodes a second, a third, and/or a fourth gRNA comprising a linking domain of no more than 25 nucleotides in length; a proximal and tail domain, that taken together, are at least 30 nucleotides in length; and a targeting domain of 17, 18, 19 or 20 nucleotides in length.

In an embodiment, a nucleic acid encodes a second, a third, and/or a fourth gRNA comprising a linking domain of no more than 25 nucleotides in length; a proximal and tail domain, that taken together, are at least 40 nucleotides in length; and a targeting domain of 17, 18, 19 or 20 nucleotides in length.

As described above, a nucleic acid may comprise (a) a sequence encoding a gRNA molecule comprising a targeting domain that is complementary with a target domain in the RHO gene, (b) a sequence encoding an RNA-guided nuclease (e.g., Cas9 or Cpfl molecule), and (c) a RHO cDNA molecule sequence. In some embodiments, (a), (b), and (c) are present on the same nucleic acid molecule, e.g., the same vector, e.g., the same viral vector, e.g., the same adeno-associated virus (AAV) vector. In an embodiment, the nucleic acid molecule is an AAV vector. Exemplary AAV vectors that may be used in any of the described compositions and methods include an AAV5 vector, a modified AAV5 vector, AAV2 vector, a modified AAV2 vector, an AAV3 vector, a modified AAV3 vector, an AAV6 vector, a modified AAV6 vector, an AAV8 vector and an AAV9 vector.

In other embodiments, (a) is present on a first nucleic acid molecule, e.g. a first vector, e.g., a first viral vector, e.g., a first AAV vector; and (b) and (c) are present on a second nucleic acid molecule, e.g., a second vector, e.g., a second vector, e.g., a second AAV vector. The first and second nucleic acid molecules may be AAV vectors.

In other embodiments, (a) and (b) are present on a first nucleic acid molecule, e.g. a first vector, e.g., a first viral vector, e.g., a first AAV vector; and (c) is present on a second nucleic acid molecule, e.g., a second vector, e.g., a second vector, e.g., a second AAV vector. The first and second nucleic acid molecules may be AAV vectors.

In other embodiments, (a) and (c) are present on a first nucleic acid molecule, e.g. a first vector, e.g., a first viral vector, e.g., a first AAV vector; and (b) is present on a second nucleic acid molecule, e.g., a second vector, e.g., a second vector, e.g., a second AAV vector. The first and second nucleic acid molecules may be AAV vectors.

In other embodiments, (a) is present on a first nucleic acid molecule, e.g. a first vector, e.g., a first viral vector, e.g., a first AAV vector; (b) is present on a second nucleic acid molecule, e.g., a second vector, e.g., a second vector, e.g., a second AAV vector; and (c) is present on a third nucleic acid molecule, e.g., a third vector, e.g., a third vector, e.g., a third AAV vector. The first, second, and third nucleic acid molecules may be AAV vectors.

In other embodiments, the nucleic acid may further comprise (d)(i) a sequence that encodes a second gRNA molecule as described herein. In some embodiments, the nucleic acid comprises (a), (b), (c), and (d)(i). Each of (a), (b), (c), and (d)(i) may be present on the same nucleic acid molecule, e.g., the same vector, e.g., the same viral vector, e.g., the same adeno-associated vims (AAV) vector. In an embodiment, the nucleic acid molecule is an AAV vector.

In other embodiments, (a) and (d)(i) are on different vectors. For example, (a) may be present on a first nucleic acid molecule, e.g. a first vector, e.g., a first viral vector, e.g., a first AAV vector; and (d)(i) may be present on a second nucleic acid molecule, e.g., a second vector, e.g., a second vector, e.g., a second AAV vector. In an embodiment, the first and second nucleic acid molecules are AAV vectors.

In other embodiments, (b) and (d)(i) are on different vectors. For example, (b) may be present on a first nucleic acid molecule, e.g. a first vector, e.g., a first viral vector, e.g., a first AAV vector; and (d)(i) may be present on a second nucleic acid molecule, e.g., a second vector, e.g., a second vector, e.g., a second AAV vector. In an embodiment, the first and second nucleic acid molecules are AAV vectors.

In other embodiments, (c) and (d)(i) are on different vectors. For example, (c) may be present on a first nucleic acid molecule, e.g. a first vector, e.g., a first viral vector, e.g., a first AAV vector; and (d)(i) may be present on a second nucleic acid molecule, e.g., a second vector, e.g., a second vector, e.g., a second AAV vector. In an embodiment, the first and second nucleic acid molecules are AAV vectors.

In another embodiment, (a) and (d)(i) are present on the same nucleic acid molecule, e.g., the same vector, e.g., the same viral vector, e.g., an AAV vector. In an embodiment, the nucleic acid molecule is an AAV vector. In an alternate embodiment, (a) and (d)(i) are encoded on a first nucleic acid molecule, e.g., a first vector, e.g., a first viral vector, e.g., a first AAV vector; and a second and third of (a) and (d)(i) are encoded on a second nucleic acid molecule, e.g., a second vector, e.g., a second vector, e.g., a second AAV vector. The first and second nucleic acid molecule may be AAV vectors.

In another embodiment, (b) and (d)(i) are present on the same nucleic acid molecule, e.g., the same vector, e.g., the same viral vector, e.g., an AAV vector. In an embodiment, the nucleic acid molecule is an AAV vector. In an alternate embodiment, (b) and (d)(i) are encoded on a first nucleic acid molecule, e.g., a first vector, e.g., a first viral vector, e.g., a first AAV vector; and a second and third of (b) and (d)(i) are encoded on a second nucleic acid molecule, e.g., a second vector, e.g., a second vector, e.g., a second AAV vector. The first and second nucleic acid molecule may be AAV vectors.

In another embodiment, (c) and (d)(i) are present on the same nucleic acid molecule, e.g., the same vector, e.g., the same viral vector, e.g., an AAV vector. In an embodiment, the nucleic acid molecule is an AAV vector. In an alternate embodiment, (c) and (d)(i) are encoded on a first nucleic acid molecule, e.g., a first vector, e.g., a first viral vector, e.g., a first AAV vector; and a second and third of (c) and (d)(i) are encoded on a second nucleic acid molecule, e.g., a second vector, e.g., a second vector, e.g., a second AAV vector. The first and second nucleic acid molecule may be AAV vectors.

In another embodiment, each of (a), (b), and (d)(i) are present on the same nucleic acid molecule, e.g., the same vector, e.g., the same viral vector, e.g., an AAV vector. In an embodiment, the nucleic acid molecule is an AAV vector. In an alternate embodiment, one of (a), (b), and (d)(i) is encoded on a first nucleic acid molecule, e.g., a first vector, e.g., a first viral vector, e.g., a first AAV vector; and a second and third of (a), (b), and (d)(i) is encoded on a second nucleic acid molecule, e.g., a second vector, e.g., a second vector, e.g., a second AAV vector. The first and second nucleic acid molecule may be AAV vectors.

In another embodiment, each of (b), (c), and (d)(i) are present on the same nucleic acid molecule, e.g., the same vector, e.g., the same viral vector, e.g., an AAV vector. In an embodiment, the nucleic acid molecule is an AAV vector. In an alternate embodiment, one of (b), (c), and (d)(i) is encoded on a first nucleic acid molecule, e.g., a first vector, e.g., a first viral vector, e.g., a first AAV vector; and a second and third of (b), (c), and (d)(i) is encoded on a second nucleic acid molecule, e.g., a second vector, e.g., a second vector, e.g., a second AAV vector. The first and second nucleic acid molecule may be AAV vectors.

In another embodiment, each of (a), (c), and (d)(i) are present on the same nucleic acid molecule, e.g., the same vector, e.g., the same viral vector, e.g., an AAV vector. In an embodiment, the nucleic acid molecule is an AAV vector. In an alternate embodiment, one of (a), (c), and (d)(i) is encoded on a first nucleic acid molecule, e.g., a first vector, e.g., a first viral vector, e.g., a first AAV vector; and a second and third of (a), (c), and (d)(i) is encoded on a second nucleic acid molecule, e.g., a second vector, e.g., a second vector, e.g., a second AAV vector. The first and second nucleic acid molecule may be AAV vectors.

In an embodiment, (a) is present on a first nucleic acid molecule, e.g., a first vector, e.g., a first viral vector, a first AAV vector; and (b), (c), and (d)(i) are present on a second nucleic acid molecule, e.g., a second vector, e.g., a second vector, e.g., a second AAV vector. The first and second nucleic acid molecule may be AAV vectors.

In other embodiments, (b) is present on a first nucleic acid molecule, e.g., a first vector, e.g., a first viral vector, e.g., a first AAV vector; and (a), (c), and (d)(i) are present on a second nucleic acid molecule, e.g., a second vector, e.g., a second vector, e.g., a second AAV vector. The first and second nucleic acid molecule may be AAV vectors.

In other embodiments, (c) is present on a first nucleic acid molecule, e.g., a first vector, e.g., a first viral vector, e.g., a first AAV vector; and (a), (b), and (d)(i) are present on a second nucleic acid molecule, e.g., a second vector, e.g., a second vector, e.g., a second AAV vector. The first and second nucleic acid molecule may be AAV vectors.

In other embodiments, (d)(i) is present on a first nucleic acid molecule, e.g., a first vector, e.g., a first viral vector, e.g., a first AAV vector; and (a), (b), and (c) are present on a second nucleic acid molecule, e.g., a second vector, e.g., a second vector, e.g., a second AAV vector. The first and second nucleic acid molecule may be AAV vectors.

In another embodiment, each of (a), (b), (c), and (d)(i) are present on different nucleic acid molecules, e.g., different vectors, e.g., different viral vectors, e.g., different AAV vector. For example, (a) may be on a first nucleic acid molecule, (b) on a second nucleic acid molecule, (c) on a third nucleic acid molecule, and (d)(i) on a fourth nucleic acid molecule. The first, second, third, and fourth nucleic acid molecule may be AAV vectors.

In another embodiment, when a third and/or fourth gRNA molecule are present, each of (a), (b), (c), (d)(i), (d)(ii) and (d)(iii) may be present on the same nucleic acid molecule, e.g., the same vector, e.g., the same viral vector, e.g., an AAV vector. In an embodiment, the nucleic acid molecule is an AAV vector. In an alternate embodiment, each of (a), (b), (c), (d)(i), (d)(ii) and (d)(iii) may be present on the different nucleic acid molecules, e.g., different vectors, e.g., the different viral vectors, e.g., different AAV vectors. In further embodiments, each of (a), (b), (c), (d)(i), (d)(ii) and (d)(iii) may be present on more than one nucleic acid molecule, but fewer than six nucleic acid molecules, e.g., AAV vectors.

The nucleic acids described herein may comprise a promoter operably linked to the sequence that encodes the gRNA molecule of (a), e.g., a promoter described herein. The nucleic acid may further comprise a second promoter operably linked to the sequence that encodes the second, third and/or fourth gRNA molecule of (d), e.g., a promoter described herein. The promoter and second promoter differ from one another. In some embodiments, the promoter and second promoter are the same. The nucleic acids described herein may further comprise a promoter operably linked to the sequence that encodes the RNA-guided nuclease (e.g., Cas9 or Cpfl molecule) of (b), e.g., a promoter described herein. In certain embodiments, the promoter operably linked to the sequence that encodes the RNA-guided nuclease of (b) comprises a rod-specific promoter. In certain embodiments, the rod- specific promoter may be a human RHO promoter. In certain embodiments, the human RHO promoter may be a minimal RHO promoter (e.g., SEQ ID NO:44).

The nucleic acids described herein may further comprise a promoter operably linked to the RHO cDNA molecule of (c), e.g., a promoter described herein. In certain embodiments, the promoter operably linked to the RHO cDNA molecule of (c) comprises a rod- specific promoter. In certain embodiments, the rod- specific promoter may be a human RHO promoter. In certain embodiments, the human RHO promoter may be a minimal RHO promoter (e.g., SEQ ID NO:44). In certain embodiments, the nucleic acids may further comprise a 3’ UTR nucleotide sequence downstream of the RHO cDNA molecule. In certain embodiments, the 3’ UTR nucleotide sequence downstream of the RHO cDNA molecule may comprise a RHO gene 3’ UTR nucleotide sequence. In certain embodiments, the 3’ UTR nucleotide sequence downstream of the RHO cDNA molecule may comprise a 3’ UTR nucleotide sequence of an mRNA encoding a highly expressed protein. For example, in certain embodiments, the 3’ UTR nucleotide sequence downstream of the RHO cDNA molecule may comprise an a-globin 3’ UTR nucleotide sequence. In certain embodiments, the 3’ UTR nucleotide sequence downstream of the RHO cDNA molecule may comprise a b- globin 3’ UTR nucleotide sequence. In certain embodiments, the 3’ UTR nucleotide sequence comprises one or more truncations at a 5’ end of said 3’ UTR nucleotide sequence, a 3’ end of said 3’ UTR nucleotide sequence, or both.

In another aspect, disclosed herein is a composition comprising (a) a gRNA molecule comprising a targeting domain that is complementary with a target domain in the RHO gene, as described herein. The composition of (a) may further comprise (b) an RNA-guided nuclease (e.g., Cas9 or Cpfl molecule as described herein). Cpfl is also sometimes referred to as Casl2a. A composition of (a) and (b) may further comprise (c) a RHO cDNA molecule. A composition of (a), (b), and (c) may further comprise (d) a second, third and/or fourth gRNA molecule, e.g., a second, third and/or fourth gRNA molecule described herein.

In another aspect, disclosed herein is a method of altering a cell, e.g., altering the structure, e.g., altering the sequence, of a target nucleic acid of a cell, comprising contacting said cell with: (a) a gRNA that targets the RHO gene, e.g., a gRNA as described herein; (b) an RNA-guided nuclease (e.g., Cas9 or Cpfl molecule as described herein); and (c) a RHO cDNA molecule; and optionally, (d) a second, third and/or fourth gRNA that targets RHO gene, e.g., a gRNA.

In some embodiments, the method comprises contacting said cell with (a) and (b).

In some embodiments, the method comprises contacting said cell with (a), (b), and

(c).

In some embodiments, the method comprises contacting said cell with (a), (b), (c) and

(d).

The gRNA of (a) and optionally (d) may comprise a targeting domain sequence selected from those set forth in Tables 1-3 and 18, or may comprise a targeting domain sequence that differs by no more than 1, 2, 3, 4, or 5 nucleotides from a targeting domain sequence set forth in any of Tables 1-3 and 18.

In some embodiments, the method comprises contacting a cell from a subject suffering from or likely to develop adRP. The cell may be from a subject having a mutation at a RHO target position.

In some embodiments, the cell being contacted in the disclosed method is a cell from the eye of the subject, e.g., a retinal cell, e.g., a photoreceptor cell. The contacting may be performed ex vivo and the contacted cell may be returned to the subject’s body after the contacting step. In other embodiments, the contacting step may be performed in vivo.

In some embodiments, the method of altering a cell as described herein comprises acquiring knowledge of the presence of a mutation in the RHO gene, in said cell, prior to the contacting step. Acquiring knowledge of a mutation in the RHO gene, in the cell may be by sequencing the RHO gene, or a portion of the RHO gene.

In some embodiments, the contacting step of the method comprises contacting the cell with a nucleic acid, e.g., a vector, e.g., an AAV vector, that expresses at least one of (a), (b), and (c). In some embodiments, the contacting step of the method comprises contacting the cell with a nucleic acid, e.g., a vector, e.g., an AAV vector, that expresses each of (a), (b), and (c). In another embodiment, the contacting step of the method comprises delivering to the cell an RNA-guided nuclease (e.g., Cas9 or Cpfl molecule) of (b) and a nucleic acid which encodes a gRNA (a), a RHO cDNA (c), and optionally, a second gRNA (d)(i), and further optionally, a third gRNA (d)(iv) and/or fourth gRNA (d)(iii).

In some embodiments, the contacting step of the method comprises contacting the cell with a nucleic acid, e.g., a vector, e.g., an AAV vector, that expresses at least one of (a), (b), (c) and (d). In some embodiments, the contacting step of the method comprises contacting the cell with a nucleic acid, e.g., a vector, e.g., an AAV vector, that expresses each of (a), (b), and (c). In another embodiment, the contacting step of the method comprises delivering to the cell an RNA-guided nuclease (e.g., Cas9 or Cpfl molecule) of (b), a nucleic acid which encodes a gRNA (a) and a RHO cDNA molecule (c), and optionally, a second gRNA (d)(i), and further optionally, a third gRNA (d)(iv) and/or fourth gRNA (d)(iii).

In an embodiment, contacting comprises contacting the cell with a nucleic acid, e.g., a vector, e.g., an AAV vector, e.g., an AAV5 vector, a modified AAV5 vector, an AAV2 vector, a modified AAV2 vector, an AAV3 vector, a modified AAV3 vector, an AAV6 vector, a modified AAV6 vector, an AAV8 vector or an AAV9 vector.

In an embodiment, contacting comprises delivering to the cell an RNA-guided nuclease (e.g., Cas9 or Cpfl molecule) of (b), as a protein or an mRNA, and a nucleic acid which encodes (a) and (c) and optionally (d).

In an embodiment, contacting comprises delivering to the cell an RNA-guided nuclease (e.g., Cas9 or Cpfl molecule) of (b), as a protein or an mRNA, said gRNA of (a), as an RNA, and optionally said second gRNA of (d), as an RNA, and the RHO cDNA molecule (c) as a DNA.

In an embodiment, contacting comprises delivering to the cell a gRNA of (a) as an RNA, optionally said second gRNA of (d) as an RNA, and a nucleic acid that encodes the RNA-guided nuclease (e.g., Cas9 or Cpfl molecule) of (b), and the RHO cDNA molecule (c) as a DNA.

In another aspect, disclosed herein is a method of treating a subject suffering from or likely to develop adRP, e.g., altering the structure, e.g., sequence, of a target nucleic acid of the subject, comprising contacting the subject (or a cell from the subject) with:

(a) a gRNA that targets the RHO gene, e.g., a gRNA disclosed herein;

(b) an RNA-guided nuclease, e.g., a Cas9 or Cpfl molecule disclosed herein; and

(c) a RHO cDNA molecule; and optionally, (d)(i) a second gRNA that targets the RHO gene, e.g., a second gRNA disclosed herein, and further optionally, (d)(ii) a third gRNA, and still further optionally, (d)(iii) a fourth gRNA that target the RHO gene, e.g., a third and fourth gRNA disclosed herein.

In some embodiments, contacting comprises contacting with (a) and (b).

In some embodiments, contacting comprises contacting with (a), (b), and (c).

In some embodiments, contacting comprises contacting with (a), (b), (c), and (d)(i). In some embodiments, contacting comprises contacting with (a), (b), (c), (d)(i) and

(d)(ii).

In some embodiments, contacting comprises contacting with (a), (b), (c), (d)(i), (d)(ii) and (d)(iii).

The gRNA of (a) or (d) (e.g., (d)(i), (d)(ii), or (d)(iii) may comprise a targeting domain sequence selected from any of those set forth in Tables 1-3 and 18, or may comprise a targeting domain sequence that differs by no more than 1, 2, 3, 4, or 5 nucleotides from a targeting domain sequence set forth in any of Tables 1-3 and 18.

In an embodiment, the method comprises acquiring knowledge of the presence of a mutation in the RHO gene, in said subject.

In an embodiment, the method comprises acquiring knowledge of the presence of a mutation in the RHO gene, in said subject by sequencing the RHO gene or a portion of the RHO gene.

In an embodiment, the method comprises altering a RHO target position in a RHO gene resulting in knocking out the RHO gene and providing exogenous RHO cDNA.

When the method comprises altering a RHO target position and providing exogenous RHO cDNA, an RNA-guided nuclease (e.g., Cas9 or Cpfl molecule) of (b), at least one guide RNA (e.g., a guide RNA of (a) and a RHO cDNA molecule (c) are included in the contacting step.

In an embodiment, a cell of the subject is contacted ex vivo with (a), (b), (c) and optionally (d). In an embodiment, said cell is returned to the subject’s body.

In an embodiment, a cell of the subject is contacted is in vivo with (a), (b), (c) and optionally (d).

In an embodiment, the cell of the subject is contacted in vivo by intravenous delivery of (a), (b), (c) and optionally (d).

In an embodiment, contacting comprises contacting the subject with a nucleic acid, e.g., a vector, e.g., an AAV vector, described herein, e.g., a nucleic acid that encodes at least one of (a), (b), (c) and optionally (d).

In an embodiment, contacting comprises delivering to said subject said RNA-guided nuclease (e.g., Cas9 or Cpfl molecule) of (b), as a protein or mRNA, and a nucleic acid which encodes (a), a RHO cDNA molecule of (c) and optionally (d).

In an embodiment, contacting comprises delivering to the subject the RNA-guided nuclease (e.g., Cas9 or Cpfl molecule) of (b), as a protein or mRNA, the gRNA of (a), as an RNA, a RHO cDNA molecule of (c) and optionally the second gRNA of (d), as an RNA. In an embodiment, contacting comprises delivering to the subject the gRNA of (a), as an RNA, optionally said second gRNA of (d), as an RNA, a nucleic acid that encodes the RNA-guided nuclease (e.g., Cas9 or Cpfl molecule) of (b), and a RHO cDNA molecule of (c).

In an embodiment, a cell of the subject is contacted ex vivo with (a), (b), (c), and optionally (d). In an embodiment, said cell is returned to the subject’s body.

In an embodiment, a cell of the subject is contacted is in vivo with (a), (b), (c) and optionally (d). In an embodiment, the cell of the subject is contacted in vivo by intravenous delivery of (a), (b), (c) and optionally (d).

In an embodiment, contacting comprises contacting the subject with a nucleic acid, e.g., a vector, e.g., an AAV vector, described herein, e.g., a nucleic acid that encodes at least one of (a), (b), (c) and optionally (d).

In an embodiment, contacting comprises delivering to said subject said RNA-guided nuclease (e.g., Cas9 or Cpfl molecule) of (b), as a protein or mRNA, and a nucleic acid which encodes (a), (c) and optionally (d).

In an embodiment, contacting comprises delivering to the subject the RNA-guided nuclease (e.g., Cas9 or Cpfl molecule) of (b), as a protein or mRNA, the gRNA of (a), as an RNA, and optionally the second gRNA of (d), as an RNA, and further optionally the RHO cDNA molecule of (c) as a DNA.

In an embodiment, contacting comprises delivering to the subject the gRNA of (a), as an RNA, optionally said second gRNA of (d), as an RNA, and a nucleic acid that encodes the RNA-guided nuclease (e.g., Cas9 or Cpfl molecule) of (b), and the RHO cDNA molecule of (c) as a DNA.

In another aspect, disclosed herein is a reaction mixture comprising a, gRNA, a nucleic acid, or a composition described herein, and a cell, e.g., a cell from a subject having, or likely to develop adRP, or a subject having a mutation in the RHO gene.

In another aspect, disclosed herein is a kit comprising, (a) gRNA molecule described herein, or nucleic acid that encodes the gRNA, and one or more of the following:

(b) an RNA-guided nuclease molecule, e.g., a Cas9 or Cpfl molecule described herein, or a nucleic acid or mRNA that encodes the RNA-guided nuclease;

(c) a RHO cDNA molecule;

(d)(i) a second gRNA molecule, e.g., a second gRNA molecule described herein or a nucleic acid that encodes (d)(i); (d)(ii) a third gRNA molecule, e.g., a second gRNA molecule described herein or a nucleic acid that encodes (d)(ii);

(d)(iii) a fourth gRNA molecule, e.g., a second gRNA molecule described herein or a nucleic acid that encodes (d)(iii).

In an embodiment, the kit comprises nucleic acid, e.g., an AAV vector, that encodes one or more of (a), (b), (c), (d)(i), (d)(ii), and (d)(iii).

In certain embodiments, the vector or nucleic acid may include a sequence set forth in one or more of SEQ ID NOs:8-ll.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present disclosure, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

Headings, including numeric and alphabetical headings and subheadings, are for organization and presentation and are not intended to be limiting.

Other features and advantages of the disclosure will be apparent from the detailed description, drawings, and from the claims.

DESCRIPTION OF THE DRAWINGS

This application contains at least one drawing executed in color. Copies of this application with color drawing(s) will be provided by the Office upon request and payment of the necessary fees.

The accompanying drawings exemplify certain aspects and embodiments of the present disclosure. The depictions in the drawings are intended to provide illustrative, and schematic rather than comprehensive, examples of certain aspects and embodiments of the present disclosure. The drawings are not intended to be limiting or binding to any particular theory or model, and are not necessarily to scale. Without limiting the foregoing, nucleic acids and polypeptides may be depicted as linear sequences, or as schematic, two- or three dimensional structures; these depictions are intended to be illustrative, rather than limiting or binding to any particular model or theory regarding their structure.

Fig. 1 illustrates the genome editing strategy implemented in certain embodiments of the disclosure. Step 1 includes knocking out (“KO”) or alteration of the RHO gene, for example, in the RHO target position of exon 1. Knocking out the RHO gene results in loss of function of the endogenous RHO gene (e.g., a mutant RHO gene). Step 2 includes replacing the RHO gene with an exogenous RHO cDNA including a minimal RHO promoter and a RHO cDNA.

Fig. 2 is a schematic of an exemplary dual AAV delivery system that may be used for a variety of applications, including without limitation, the alteration of the RHO target position, according to certain embodiments of the disclosure. Vector 1 shows an AAV5 genome, which encodes ITRs, a GRK1 promoter, and a Cas9 molecule flanked by NLS sequences. Vector 2 shows an AAV5 genome, which encodes ITRs, a minimal RHO promoter, a RHO cDNA molecule, a U6 promoter, and a gRNA. In certain embodiments, the AAV vectors may be delivered via subretinal injection.

Fig. 3 is a schematic of an exemplary dual AAV delivery system that may be used for a variety of applications, including without limitation, the alteration of the RHO target position, according to certain embodiments of the disclosure. Vector 1 shows an AAV5 genome, which encodes a minimal RHO promoter and a Cas9 molecule. Vector 2 shows an AAV5 genome, which encodes a minimal RHO promoter, a RHO cDNA molecule, a U6 promoter, and a gRNA. In certain embodiments, the AAV vectors may be delivered via subretinal injection.

Fig. 4 depicts the percentage of indels in the RHO gene in HEK293 cells formed by dose-dependent gene editing using ribonucleoproteins (RNPs) comprising RHO-3, RHO-7, or RHO-10 gRNAs (Table 17) and SaCas9. Increasing concentrations of RNP were delivered to HEK293 cells. Indels of the RHO gene were assessed using next generation sequencing (NGS). Data from RNP comprising RHO-3 gRNA, RHO-10 gRNA, or RHO-7 gRNA are represented by circles, squares, and triangles, respectively. Data from control plasmid (expressing Cas9 with scrambled gRNA that does not target a sequence within the human genome) are represented by X.

Fig. 5 shows details characterizing the predicted gRNA RHO alleles generated by editing with RNPs comprising the RHO-3, RHO-7, or RHO-10 gRNAs (Table 17). As shown in the schematic of the human RHO cDNA and corresponding exons at the bottom of Fig. 5, RHO-3, RHO-10, and RHO-7 gRNAs are predicted to cut the RHO cDNA at Exon 1, the Exon 2/Intron 2 border, and the Exon 1/Intron 1 border, respectively. The target site positions for RHO-3, RHO-10, and RHO-7 gRNAs are located at bases encoding amino acids (AA) 96, 174, and 120 of the RHO protein, respectively. The protein lengths for each resulting construct for the predicted -1, -2, and -3 frame shifts are set forth. For RHO-3, a 1 base deletion at position 96 results in a truncated protein that is 95 amino acids long, a 2 base deletion at position 96 results in a truncated protein that is 120 amino acids long, a 3 base deletion at position 96 results in a truncated protein that is 347 amino acids long. For RHO- 10, a 1 base deletion at position 174 results in a truncated protein that is 215 amino acids long, a 2 base deletion at position 174 results in a truncated protein that is 328 amino acids long, a 3 base deletion at position 174 results in a truncated protein that is 347 amino acids long. For RHO-7, a 1 base deletion at position 120 results in a truncated protein that is 142 amino acids long, a 2 base deletion at position 120 results in a truncated protein that is 142 amino acids long, a 3 base deletion at position 120 results in a truncated protein that is 347 amino acids long. Fig 6. provides schematics of the predicted truncated proteins.

Fig. 6 shows schematics of the predicted RHO alleles generated by RHO-3, RHO-7, or RHO- 10 gRNAs (Table 17). RHO alleles were predicted based on deletions of 1, 2, or 3 base pairs at the RHO-3, RHO-7, or RHO-10 cut sites. RHO Exons are represented by dark grey, stop codons are represented by black, missense protein is represented by stripes, deletions are represented by light grey.

Figs. 7A and 7B show the viability of HEK293 cells expressing wild-type or mock- edited RHO alleles. Schematics of RHO alleles predicted to be generated by RHO-3, RHO-7, and RHO-10 gRNAs (Table 17) having 1 base pair (bp), 2bp or 3bp deletions are illustrated in Fig. 6. RHO mutations predicted to be generated from RHO-3, RHO-7, and RHO-10 gRNAs (i.e., mock-edited RHO alleles) were generated using either WT-RHO cDNA or RHO cDNA expressing the P23H RHO variant. Wild-type RHO, mock-edited RHO alleles, or RHO alleles expressing the P23H RHO variant were cloned into mammalian expression plasmids, lipofected into HEK293 cells and assessed for cell viability after 48 hours using the ATPLite Luminescence Assay by Perkin Elmer. Fig. 7A shows viability depicted by luminescence of cells with modified WT RHO alleles. Fig. 7B shows viability depicted by luminescence of cells with modified P23H RHO alleles. The upper dotted line represents the level of luminescence from WT RHO alleles and the lower dotted line represents the level of luminescence from the P23H RHO alleles.

Fig. 8 shows editing of rod photoreceptors in non-human primate (NHP) explants using RHO-9 gRNA (Table 1). RNA from a rod-specific mRNA (neural retina leucine zipper (NRL)) was extracted from the explants and measured to determine the percentage of rods present in the explants. RNA from beta actin (ACTB) was also measured to determine the total number of cells. The x-axis shows the delta between ACTB and NRL RNA levels as measured by RT-PCR, which is a measure for the percentage of rods in the explant at the time of lysing the explants. Indels of the RHO gene were assessed using next generation sequencing (NGS). Each circle represents data from a different explant.

Fig. 9 shows a schematic of the plasmid for the dual luciferase system used for optimizing the RHO replacement vector.

Fig. 10 depicts the ratio of firefly/renilla luciferase luminescence using the dual luciferase system to test the effects of different lengths of the RHO promoter on RHO expression. The lengths of the RHO promoter that were tested ranged from 3.0 Kb to 250 bp.

Figs. 11A and 11B depict the effects on RHO mRNA and RHO protein expression of adding various 3’ UTRs to the RHO replacement vector. The HBA1 3’ UTR (SEQ ID NO:38), short HBA1 3’ UTR (SEQ ID NO:39), TH 3’ UTR (SEQ ID NO:40), COL1A1 3 ’UTR (SEQ ID NO:41), ALOX15 3’UTR (SEQ ID NO:42), and minUTR (SEQ ID NO:56) were tested. Fig. 11A shows results using RT-qPCR to measure RHO mRNA expression. Fig. 11B shows results using a RHO ELISA assay to measure RHO protein expression.

Fig. 12 depicts the effects on RHO protein expression of inserting different RHO introns into RHO cDNA in the RHO replacement vector. The various RHO cDNA sequences with inserted introns (i.e, Introns 1-4) are set forth in SEQ ID NOs: 4-7, respectively.

Fig. 13 depicts the effects on RHO protein expression of using cDNA comprising the wild-type RHO sequence (WT-RHO) or cDNA comprising different codon optimized sequences in the RHO replacement vector. The various codon optimized RHO cDNA sequences (i.e., Codon 1-6) are set forth in SEQ ID NOs: 13-18, respectively. The RHO cDNAs were under the control of a CMV or EFS promoter.

Figs. 14A and 14B depict in vivo editing of the RHO gene and knock down of Cas9 using a self-limiting Cas9 vector system (“SD”). Fig. 14A shows successful knockdown of Cas9 levels using the self-limiting Cas9 vector system (i.e., “SD Cas9 + Rho”). Fig. 14B shows successful editing using the self-limiting Cas9 vector system (i.e., “SD Cas9”).

Fig. 15 depicts RHO expression in human explants. Explants were transduced with “shRNA”: transduction of retinal explants with shRNA targeting the RHO gene and a replacement vector providing a RHO cDNA (as published in Cideciyan 2018); “Vector A”: a two- vector system (Vector 1 comprising SaCas9 driven by the minimal RHO promoter (250 bp), and Vector 2 comprising a codon-optimized RHO cDNA (codon-6) and comprising a HBA1 3’ UTR under the control of the minimal 250 bp RHO promoter, as well as the RHO-9 gRNA (Table 1) under the control of a U6 promoter); “Vector B”: a two-vector system identical to “Vector A” except for Vector 2 comprising a wt RHO cDNA; and “UTC”: untransduced control. Fig. 16 is a schematic of an exemplary AAV vector (SEQ ID NO: 11) according to certain embodiments of the disclosure. The schematic shows an AAV5 genome comprising and encoding an ITR (SEQ ID NO:92), a first U6 promoter (SEQ ID NO:78), a first RHO-7 gRNA (comprising a RHO-7 gRNA targeting domain (SEQ ID NO:606) (DNA) and SEQ ID NO: 12), a second U6 promoter (SEQ ID NO:78), a second RHO-7 gRNA (comprising a RHO-7 gRNA targeting domain (SEQ ID NO:606) (DNA) and SEQ ID NO: 12), a minimum RHO Promoter (250 bp) (SEQ ID NO:44), an SV40 Intron (SEQ ID NO:94), a codon optimized RHO cDNA (SEQ ID NO: 18), HBA1 3’ UTR (SEQ ID NO:38), a minipolyA (SEQ ID NO:56), and a 3’ ITR (SEQ ID NO:93). In certain embodiments, the AAV vector may be delivered via subretinal injection.

Fig. 17 is a schematic of an exemplary AAV vector (SEQ ID NO: 10) according to certain embodiments of the disclosure. The schematic shows an AAV5 genome comprising and encoding an ITR (SEQ ID NO:92), a minimum RHO Promoter (250 bp) (SEQ ID NO:44), an SV40 Intron (SEQ ID NO:94), an NLS sequence, an S. aureus Cas9 sequence, an SV40 NLS, an HBA1 3’ UTR (SEQ ID NO:38), and a 3’ ITR (SEQ ID NO:93). In certain embodiments, the AAV vector may be delivered via subretinal injection.

Fig. 18 is a schematic of an exemplary AAV vector (SEQ ID NO:9) according to certain embodiments of the disclosure. The schematic shows an AAV5 genome comprising and encoding an ITR (SEQ ID NO:92), a minimum RHO Promoter (625 bp), an SV40 SA/SD, an NLS, an S. aureus Cas9 sequence, an SV40 NLS, a minipolyA (SEQ ID NO:56), and a 3’ ITR (SEQ ID NO: 93). In certain embodiments, the AAV vector may be delivered via subretinal injection.

Figs. 19A-19B depict a schematic of lentivirus CMV-RHO-mCherry and results from experiments where guides RHO-3, RHO-7, RHO- 10 were used to knockdown RHO-mCherry in a HEK293 cell line generated using the lentivirus. Fig. 19A is a schematic of lentivirus CMV-RHO-mCherry (pLVX-Puro). Fig. 19B depicts dose-dependent knockdown of RHO- mCherry in a stable HEK293T cell line generated using the lentivirus.

Fig. 20 shows the editing profile in human retinal explants after treatment with a dual AAV5 vector system targeting RHO in the explants (using either the RHO-3 gRNA or the RHO-7 gRNA). The frameshifting profile of the indels generated using either RHO-3 or RHO-7 gRNA was determined by NGS 4-weeks post transduction.

Fig. 21 depicts results from testing various vector configurations of the “replace” AAV vector as plasmids in HEK293 cells. The optimized vector, Vector 7 shown in Fig. 21, performs 16-fold better than the “benchmark” vector (as published in Cideciyan 2018) in generating RHO mRNA based on RT-qPCR. The sequence of Vector 7 comprises the sequence set forth in SEQ ID NO: 11 as shown in Fig. 16. The different configurations of the vectors are provided in Table 19.

Fig. 22 depicts results from testing the optimized “replace” vector (Vector 7 sequence comprises the sequence set forth in SEQ ID NO: 11) in human retinal explants. Human retinal explants were transduced at seven concentrations ranging from lxlO ⁹ vg/ml to lxlO ¹² vg/ml and RHO mRNA levels were determined by RT-qPCR at 4-weeks post transduction. RHO mRNA levels expressed from the replace vector are equivalent to endogenous RHO levels (“WT”) at about lxlO ¹¹ vg/ml and above.

Fig. 23 is a schematic of an exemplary dual AAV delivery system that may be used for a variety of applications, including without limitation, the alteration of the RHO target position, according to certain embodiments of the disclosure. “Vector l:SaCas9” shows an AAV5 genome, which encodes a minimal RHO promoter and a SaCas9 molecule. “Vector 2:gRNA and exogenous RHO” shows an AAV5 genome, which includes a U6 promoter, a gRNA, a U6 promoter, a gRNA, a minimal RHO promoter, and a RHO cDNA molecule (exogenous RHO). In certain embodiments, the two gRNA sequences can be the same, e.g., the two sequences encode gRNAs that target the same genomic site. In other embodiments, the two gRNA sequences are different, e.g., the two sequences encode gRNAs that target different genomic sites. In certain embodiments, Vectors 1 and/or 2 may contain an SV40 intron at the 5’ end. In certain embodiments, Vectors 1 and/or 2 may contain a stable UTR and/or polyA (e.g., miniPoly A) at the 3’ end of the encoded SaCas9 or exogenous RHO cDNA. In certain embodiments, the SaCas9 may contain one or more NLS sequences on the N terminus and/or the C terminus. In certain embodiments, Vector 1 of Fig. 23 comprises the sequence set forth in SEQ ID NO: 10. In certain embodiments, Vector 1 comprises the sequence set forth in SEQ ID NO: 1005. In certain embodiments, Vector 2 of Fig. 23 comprises the sequence set forth in SEQ ID NO: 11 when used with a RHO-7 gRNA. In certain embodiments, the RHO-7 gRNA sequence may be replaced with a different gRNA.

In certain embodiments, Vector 2 comprises the sequence set forth in SEQ ID NO: 1006. In certain embodiments, the AAV vectors may be delivered via subretinal injection.

Fig. 24 shows a schematic of a humanized mRHO ^hRHO/+ mouse used in Example 10.

Fig. 25 depicts the percentage of normalized productive editing seen in mRho ^hRHO/+ mice post- injection of the dual AAV vector systems of Vector 1 (encoding SaCas9) and Vector 2 (encoding RHO-3 or RHO-7 gRNAs). Vector 1 comprises the sequence set forth in SEQ ID NO: 1005. Vector 2 containing the RHO-7 gRNA comprises the sequence set forth in SEQ ID NO: 11. Vector 2 containing the RHO-3 gRNA comprises the sequence set forth in SEQ ID NO: 1006. The black dotted line indicates the threshold to achieve therapeutic efficacy (> 25%, see Cideciyan 1998). Uni-Directional Targeted Sequencing (UDiTaS) was performed at 6 weeks and 13 weeks post- injection. Vehicle samples are represented by the lighter grey circles (the circles in the left lane of week 6 and week 13 samples). RHO-3 samples are represented by the grey circles (the circles in the middle lane of week 6 and week 13 samples). RHO-7 samples are represented by the black circles (the circles in the right lane of week 6 and week 13 samples). **** indicates p < 0.0001.

Fig. 26 depicts the indel profiles for RHO-3 and RHO-7 samples at 6 weeks and 13 weeks seen in mRho ^hRHO/+ mice post-injection of the dual AAV vector systems of Vector 1 (encoding SaCas9) and Vector 2 (encoding RHO-3 or RHO-7 gRNA). Vector 1 comprises the sequence set forth in SEQ ID NO: 1005. Vector 2 containing the RHO-7 gRNA comprises the sequence set forth in SEQ ID NO: 11. Vector 2 containing the RHO-3 gRNA comprises the sequence set forth in SEQ ID NO: 1006. The indel size (base pairs (bp)) is indicated on the x-axis. The indel pattern remains unchanged from week 6 to week 13 demonstrating that none of the novel alleles generated by on-target editing have a dominant negative phenotype. The rectangular box at -3 bp indicates that in-frame edits that appeared to demonstrate a dominant negative phenotype in vitro (Fig. 7), do not exhibit this phenotype in vivo.

Fig. 27 depicts the percentage of normalized productive editing in mRho ^hRHO/+ mice post- injection of various ratios of the dual AAV vector system of Vector 1 (encoding SaCas9) and Vector 2 (encoding RHO-3 gRNA). Vector 1 comprises the sequence set forth in SEQ ID NO: 1005. Vector 2 containing the RHO-3 gRNA comprises the sequence set forth in SEQ ID NO: 1006. The black dotted line indicates the threshold to achieve therapeutic efficacy (> 25%, see Cideciyan 1998). UDiTaS was performed at 6 weeks post-injection. * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001.

Fig. 28 depicts the amount of RHO-3 gRNA mRNA expression in mRho ^hRHO/+ mice at 6 weeks post- injection of various ratios of the dual AAV vector system of Vector 1 (encoding SaCas9) and Vector 2 (encoding RHO-3 gRNAs). Vector 1 comprises the sequence set forth in SEQ ID NO: 1005. Vector 2 containing the RHO-3 gRNA comprises the sequence set forth in SEQ ID NO: 1006. * p < 0.05.

Fig. 29 depicts the amount of Cas9 mRNA expression in mRho ^hRHO/+ mice at 6 weeks post- injection of various ratios of the dual AAV vector system of Vector 1 (encoding SaCas9) and Vector 2 (encoding RHO-3 gRNAs). Vector 1 comprises the sequence set forth in SEQ ID NO:1005. Vector 2 containing the RHO-3 gRNA comprises the sequence set forth in SEQ ID NO:1006. * p < 0.05, ** p < 0.01. Fig.30 depicts the amount of endogenous human RHO expression (hRHO mRNA) in mRho ^hRHO/+ mice at 6 weeks post-injection of various ratios of the dual AAV vector system of Vector 1 (encoding SaCas9) and Vector 2 (encoding RHO-3 gRNA). Vector 1 comprises the sequence set forth in SEQ ID NO:1005. Vector 2 containing the RHO-3 gRNA comprises the sequence set forth in SEQ ID NO:1006. * p < 0.05. Fig.31 depicts the amount of replacement RHO expression (exogenous codon optimized RHO (coRHO) mRNA) in mRho ^hRHO/+ mice at 6 weeks post-injection of various ratios of the dual AAV vector system of Vector 1 (encoding SaCas9) and Vector 2 (encoding RHO-3 gRNA). Vector 1 comprises the sequence set forth in SEQ ID NO:1005. Vector 2 containing the RHO-3 gRNA comprises the sequence set forth in SEQ ID NO:1006. * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001. Figs.32A-32B depict editing seen with increasing concentrations (1x10 ¹¹ , 3x10 ¹¹ , ^{1x1012, 3x1012, 6x1012 and 9x1012 vg/ml} _{) of Vector 1 + Vector 2. Vector 1 comprises the} sequence set forth in SEQ ID NO:1005. Vector 2 containing the RHO-3 gRNA comprises the sequence set forth in SEQ ID NO:1006. UDiTaS was performed at 6 weeks post- injection. Fig.32A depicts the percentage of normalized productive editing. The grey dotted line indicates the threshold to achieve therapeutic efficacy (≥ 25%, see Cideciyan 1998). * p < 0.05; ** p <0.005; *** p <0.0005; **** p <0.0001 vs. vehicle. Data are presented as geometric mean ± 95% CI. Kruskal–Wallis test with Dunn’s multiple comparison analysis. Fig.32B depicts the percentage of normalized productive editing on the X-axis and the relative editing frequency (%) on the Y-axis. The dotted line indicates the threshold to achieve therapeutic efficacy (≥ 25%, see Cideciyan 1998). Figs.33A-33B depict the amount of gRNA and Cas9 expression seen with increasing _{concentrations (} ^{1x1011, 3x1011, 1x1012, 3x1012, 6x1012 and 9x1012 vg/ml} _{) of Vector 1 + Vector} 2. Vector 1 comprises the sequence set forth in SEQ ID NO:1005. Vector 2 containing the RHO-3 gRNA comprises the sequence set forth in SEQ ID NO:1006. Fig.33A depicts the expression levels (mRNA molecule/µg of total RNA) of gRNA and Cas9 for each concentration tested. Data are presented as geometric mean ± 95% CI. Kruskal–Wallis test with Dunn’s multiple comparison analysis. * p <0.05; ** p <0.005; *** p <0.0005; **** p <0.0001 vs 1E+11 vg/ml; # p <0.05; ## p <0.005; ### p <0.0005; #### p <0.0001 vs 3E+11 vg/ml; + p <0.05; ++ p <0.005; +++ p <0.0005; ++++ p <0.0001 vs 1E+12 vg/ml. Fig.33B depicts the correlation between editing and Cas9 mRNA and gRNA levels for each concentration tested. The expression levels (mRNA molecule/µg of total RNA) of gRNA and Cas9 are depicted on the X-axis and the percentage of normalized productive editing for gRNA and Cas9 are depicted on the Y-axis. Spearman’s correlation was computed to obtain the r values. Fig.34 depicts the amount of replacement RHO mRNA (coRHO) as determined by nanostring counts normalized to G6PD for increasing concentrations (1x10 ¹¹ , 3x10 ¹¹ , 1x10 ¹² , 3x10 ¹² , 6x10 ¹² and 9x10 ¹² vg/ml) of Vector 1 + Vector 2. Vector 1 comprises the sequence set forth in SEQ ID NO:1005. Vector 2 containing the RHO-7 gRNA comprises the sequence set forth in SEQ ID NO:11. Vector 2 containing the RHO-3 gRNA comprises the sequence set forth in SEQ ID NO:1006. Data are presented as geometric mean ± 95% CI. Kruskal– Wallis test with Dunn’s multiple comparison analysis. * p <0.05; ** p <0.005; *** p <0.0005; **** p <0.0001 vs 1E+11 vg/ml; # p <0.05; ## p <0.005; ### p <0.0005; #### p <0.0001 vs 3E+11 vg/ml; + p <0.05; ++ p <0.005; +++ p <0.0005; ++++ p <0.0001 vs 1E+12 vg/ml. Fig.35 depicts the amount of endogenous RHO mRNA (hRHO) as determined by nanostring counts normalized to G6PD for increasing concentrations (1x10 ¹¹ , 3x10 ¹¹ , 1x10 ¹² , 3x10 ¹² , 6x10 ¹² and 9x10 ¹² vg/ml) of Vector 1 + Vector 2. Vector 1 comprises the sequence set forth in SEQ ID NO:1005. Vector 2 containing the RHO-7 gRNA comprises the sequence set forth in SEQ ID NO:11. Vector 2 containing the RHO-3 gRNA comprises the sequence set forth in SEQ ID NO:1006. Data are presented as geometric mean ± 95% CI. Kruskal– Wallis test with Dunn’s multiple comparison analysis. * p <0.05; ** p <0.005; *** p <0.0005; **** p <0.0001 vs Vehicle. Fig.36 depicts the percentage of normalized productive editing at 1, 3, 6, and 13 _{weeks post-dosing for (Vehicle (bottom line),} ^{1x1012 vg/ml (second line from bottom), 3x1012} vg/ml (second line from top), and 6x10 ¹² vg/ml (top line)) of Vector 1 + Vector 2. Vector 1 comprises the sequence set forth in SEQ ID NO:1005. Vector 2 containing the RHO-3 gRNA comprises the sequence set forth in SEQ ID NO:1006. Data are presented as geometric mean ± 95% CI. Kruskal–Wallis test with Dunn’s multiple comparison analysis. * p <0.05; ** p <0.005; *** p <0.0005; **** p <0.0001 vs Vehicle (at the same time point). Figs.37A-37C depict the amount of gRNA and Cas9 mRNA. Figs.37A and 37B depict the amount (molecule/µg of total RNA) of gRNA or Cas9 mRNA, respectively, at 1, 3, 6, and 13 weeks post-dosing for various concentrations (1x10 ¹² vg/ml (bottom line), 3x10 ¹² vg/ml (middle line), and 6x10 ¹² vg/ml (top line)) of Vector 1 + Vector 2. Vector 1 comprises the sequence set forth in SEQ ID NO:1005. Vector 2 containing the RHO-3 gRNA comprises the sequence set forth in SEQ ID NO: 1006. Data are presented as geometric mean ± 95% Cl. Kruskal-Wallis test with Dunn’s multiple comparison analysis. Comparison was performed in the same time point. * p <0.05; ** p <0.005; *** p <0.0005; **** p <0.0001 vs 1E+12 vg/ml. Fig. 37C depicts the amount (molecule/pg of total RNA) of gRNA and Cas9 mRNA on the X-axis and the percentage of normalized productive editing for gRNA and Cas9 on the Y-axis. Spearman’s correlation was computed to obtain the r values.

Fig. 38 depicts the amount of replacement RHO mRNA (coRHO) as determined by nanostring counts normalized to G6PD for increasing concentrations (lxlO ¹² vg/ml (bottom line), 3xl0 ¹² vg/ml (middle line), 6xl0 ¹² vg/ml (top line)) of Vector 1 + Vector 2 at weeks 1, 3, 6, and 13 post-dosing. Vector 1 comprises the sequence set forth in SEQ ID NO: 1005.

Vector 2 containing the RHO-3 gRNA comprises the sequence set forth in SEQ ID NO: 1006. Data are presented as geometric mean ± 95% Cl. Kruskal-Wallis test with Dunn’s multiple comparison analysis. Comparison was performed in the same time point. * p <0.05; ** p <0.005; *** p <0.0005; **** p <0.0001 vs 1E+12 vg/ml.

Fig. 39 depicts the amount of endogenous RHO mRNA (hRHO) as determined by nanostring counts normalized to G6PD for increasing concentrations (Vehicle, lxlO ¹² vg/ml, 3xl0 ¹² vg/ml, 6xl0 ¹² vg/ml) of Vector 1 + Vector 2 at weeks 1, 3, 6, and 13 post-dosing. Vector 1 comprises the sequence set forth in SEQ ID NO: 1005. Vector 2 containing the RHO-3 gRNA comprises the sequence set forth in SEQ ID NO: 1006. Data are presented as geometric mean ± 95% Cl. Kruskal-Wallis test with Dunn’s multiple comparison analysis. * p <0.05; ** p <0.005; *** p <0.0005; **** p <0.0001 vs Vehicle (at the same time point).

Fig. 40 shows a schematic of two dual vector systems: knock out and replace (KO&R) dual vector (top) and knock out (KO) only dual vector (bottom). The KO&R dual vector includes Vector 1 (SaCas9) and Vector 2 (gRNA and exogenous RHO (coRHO)). Vector 1 of the KO&R dual vector includes a minimal RHO promoter and a SaCas9 cDNA sequence. Vector 2 of the KO&R dual vector includes a U6 promoter, a gRNA, a U6 promoter, gRNA, a minimal RHO promoter, and a RHO cDNA molecule (exogenous RHO (coRHO)). In certain embodiments, the two gRNA sequences can be the same, e.g., the two sequences encode gRNAs that target the same genomic site. In other embodiments, the two gRNA sequences are different, e.g., the two sequences encode gRNAs that target different genomic sites. In certain embodiments, Vectors 1 and/or 2 of the KO&R dual vector may contain an SV40 intron at the 5’ end. In certain embodiments, Vectors 1 and/or 2 of the KO&R dual vector may contain a stable UTR and/or polyA (e.g., miniPolyA) at the 3’ end of the encoded SaCas9 and/or exogenous RHO cDNA. In certain embodiments, the SaCas9 may contain one or more NLS sequences on the N terminus and/or the C terminus. In certain embodiments, Vector 1 of the KO&R dual vector of Fig.40 comprises the sequence set forth in SEQ ID NO:1005. In certain embodiments, Vector 2 of the KO&R dual vector of Fig.40 comprises the sequence set forth in SEQ ID NO:1006. The KO dual vector of Fig.40 includes Vector 1 (SaCas9) and Vector 2 (gRNA and a stuffer sequence). Vector 1 of the KO dual vector includes a minimal RHO promoter and a SaCas9 cDNA sequence. In certain embodiments, Vector 1 of the KO dual vector of Fig.40 comprises the sequence set forth in SEQ ID NO:1005. Vector 2 of the KO dual vector includes a U6 promoter, a gRNA, a U6 promoter, a gRNA, and a stuffer sequence. Fig.41 shows a representative image of the bleb area (transduced area) generated by subretinal injections adjacent to the macula in a non-human primate (NHP). “OS” = oculus sinister. Figs.42A-42C depict the editing and expression levels of gRNA and Cas9 and their correlation following injection of the KO&R dual vectors or controls into the tested NHP eyes. Fig.42A depicts the percentage of normalized productive editing within the area of the eye (bleb area) transduced with Vehicle, the knock out dual vector (“KO”, at 3x10 ¹² vg/ml), or the knock out and replace dual vector (“KO&R”, at 3x10 ¹² vg/ml and at 6x10 ¹² vg/ml). Fig.42B depicts the amount (molecule/µg of total RNA) of gRNA and SaCas9 mRNA within the area of the eye (bleb area) transduced with the knock out dual vector (“KO”, at 3x10 ¹² vg/ml) or the knock out and replace dual vector (“KO&R”, at 3x10 ¹² vg/ml and at 6x10 ¹² vg/ml). Fig.42C depicts the amount (molecule/µg of total RNA) of gRNA and Cas9 mRNA on the X-axis and the percentage of normalized productive editing for gRNA and Cas9 on the Y-axis. Data presented as mean ± SD. Ordinary one-way ANOVA with Tukey’s multiple comparison analysis. * P<0.005; ** P<0.0005; *** P<0.0001 vs Vehicle. Spearman’s correlation was computed to obtain the r values. Figs.43A-43D depicts the amount of replacement and endogenous RHO levels in non-human primates at 13 weeks post-injection with Vehicle, the knock out dual vector (“KO”, at 3x10 ¹² vg/ml), or the knock out and replace dual vector (“KO&R”, at 3x10 ¹² vg/ml and at 6x10 ¹² vg/ml). Fig.43A depicts the percentage (%) of endogenous NHP RHO mRNA levels compared to the amount of endogenous RHO mRNA in the Vehicle. Levels of NHP RHO mRNA levels were detected with two different primers/probe set, Probe 1 and Probe 2. Fig.43B depicts the percentage (%) of endogenous NHP RHO protein compared to the amount of endogenous NHP RHO protein levels in the Vehicle. Fig.43C depicts the percentage (%) of replacement human RHO mRNA compared to the amount of endogenous human RHO mRNA in the Vehicle control. Fig. 43D depicts the percentage (%) of replacement human RHO protein compared to the amount of replacement human RHO protein in the Vehicle control. Endogenous NHP and replacement human RHO mRNA levels were determined by NanoString counts normalized to housekeeping genes. Endogenous NHP and replacement human RHO protein levels were determined by mass spectrometry. Data presented as mean ± SD. Ordinary one-way ANOVA with Tukey’s multiple comparison analysis. * P<0.05, ** P<0.005; *** P<0.0005; **** P<0.0001 vs Vehicle.

Fig. 44 shows micrographs from histological sections of non-human primate retinal tissue treated with Vehicle, 3xl0 ¹² vg/ml of the knock out dual vector (“KO”), or 3xl0 ¹² vg/ml or 6xl0 ¹² vg/ml of the knock out and replace dual vector (“KO&R”). Retinas were stained to positively identify Cas9 genome by in situ hybridization (ISH) and RHO protein by immunohistochemistry (IHC). RHO protein expression is indicated by arrowheads while Cas9 staining is indicated by arrows.

Fig. 45 shows micrographs of hematoxilin and eosin-stained sections of non-human primate retinal tissue treated with Vehicle, 3xl0 ¹² vg/ml of the knock out dual vector (“KO”), or 3xl0 ¹² vg/ml or 6xl0 ¹² vg/ml of the knock out and replace dual vector (“KO&R”). Inner and outer segment photoreceptor morphology is indicated by arrows.

Figs. 46A-46B depict the amplitude of ERG a- wave (Fig. 46A) and b-wave (Fig.

46B) in non-human primates at 13 weeks post-injection of Vehicle, 3xl0 ¹² vg/ml of the knock out dual vector (“KO”), or 3xl0 ¹² vg/ml or 6xl0 ¹² vg/ml of the knock out and replace dual vector (“KO&R”). Amplitude of ERG a-wave and b-wave amplitude is represented as percentage of a-wave and b-wave amplitude detected in the Vehicle group. Data presented as mean ± SD. Ordinary one-way ANOVA with Tukey’s multiple comparison analysis. * P<0.05; ** P<0.005; *** P<0.0005, ****P<0.0001 vs KO.

DETAILED DESCRIPTION

Definitions

“Domain”, as used herein, is used to describe segments of a protein or nucleic acid. Unless otherwise indicated, a domain is not required to have any specific functional property.

Calculations of homology or sequence identity between two sequences (the terms are used interchangeably herein) are performed as follows. The sequences are aligned for optimal comparison purposes (e.g., gaps can be introduced in one or both of a first and a second amino acid or nucleic acid sequence for optimal alignment and non-homologous sequences can be disregarded for comparison purposes). The optimal alignment is determined as the best score using the GAP program in the GCG software package with a Blossum 62 scoring matrix with a gap penalty of 12, a gap extend penalty of 4, and a frame shift gap penalty of 5. The amino acid residues or nucleotides at corresponding amino acid positions or nucleotide positions are then compared. When a position in the first sequence is occupied by the same amino acid residue or nucleotide as the corresponding position in the second sequence, then the molecules are identical at that position. The percent identity between the two sequences is a function of the number of identical positions shared by the sequences.

“Polypeptide”, as used herein, refers to a polymer of amino acids having less than 100 amino acid residues. In an embodiment, it has less than 50, 20, or 10 amino acid residues.

“Replacement”, or “replaced”, as used herein with does not require the removal of an endogenous entity, e.g., a molecule (e.g., a gene) or protein, in a cell followed by the insertion of a replacement entity, e.g., a molecule or protein, into the cell, but rather just requires that a replacement entity, e.g., a molecule or protein, is present in the cell. In some embodiments, a mutant allele or mutant alleles of RHO that produce non-functional or aberrant RHO protein is replaced with a “replacement” vector that expresses a functional RHO protein.

“ RHO target position,” as that term is used herein, refers to a target position, e.g., one or more nucleotides, in or near the RHO gene, that are targeted for alteration using the methods described herein. In certain embodiments, alteration of the RHO target position, e.g., by substitution, deletion, or insertion, may result in disruption (e.g., “knocking down” or “knocking out”) of the RHO gene. In certain embodiments, the RHO target position may be located in a 5’ region of the RHO gene (e.g., 5’ UTR, exon 1, exon 2, intron 1, the exon 1/intron 1 border, or the exon 2/intron 1 border), a non-coding region of the RHO gene (e.g., an enhancer region, a promoter region, an intron, 5’ UTR, 3 ’UTR, polyadenylation signal), or a coding region of the RHO gene (e.g., early coding region, an exon (e.g., exon 1, exon 2, exon 3, exon 4, exon 5), or an exon/intron border (e.g., exon 1/intronl, exon 2/intron 1) of the RHO gene.

“Subject”, as used herein, may mean either a human or non-human animal. The term includes, but is not limited to, mammals (e.g., humans, other primates, pigs, rodents (e.g., mice and rats or hamsters), rabbits, guinea pigs, cows, horses, cats, dogs, sheep, and goats).

In an embodiment, the subject is a human. In other embodiments, the subject is a non-human primate. “Treat”, “treating” and “treatment”, as used herein, mean the treatment of a disease in a mammal, e.g., in a human, including (a) inhibiting the disease, i.e., arresting or preventing its development; (b) relieving the disease, i.e., causing regression of the disease state; and (c) curing the disease. In some embodiments, a retinitis pigmentosa, e.g., an autosomal- dominant RP (adRP), autosomal recessive RP (arRP) or X-linked RP (X-LRP), is treated in a subject, e.g., a human subject. In some cases, a composition described herein (e.g., containing a dual vector system) is administered to a human subject with retinitis pigmentosa resulting in an alteration that reduces the expression of an endogenous mutant RHO gene and the expression of a functional replacement RHO protein, thereby treating the retinitis pigmentosa of the subject.

“X” as used herein in the context of an amino acid sequence, refers to any amino acid (e.g., any of the twenty natural amino acids) unless otherwise specified.

Autosomal-dominant retinitis pigmentosa (adRP)

Retinitis pigmentosa (RP) affects between 50,000 and 100,000 people in the United States. RP is a group of inherited retinal dystrophies that affect photoreceptors and retinal pigment epithelium cells. The disease causes retinal deterioration and atrophy, and is characterized by progressive deterioration of vision, ultimately resulting in blindness.

Typical disease onset is during the teenage years, although some subjects may present in early adulthood. Subjects initially present with poor night vision and declining peripheral vision. In general, visual loss proceeds from the peripheral visual field inwards. The majority of subjects are legally blind by the age of 40. The central visual field may be spared through the late stages of the disease, so that some subjects may have normal visual acuity within a small visual field into their 70’s. However, the majority of subjects lose their central vision as well between the age of 50 and 80 (Berson 1990). Upon examination, a subject may have one or more of bone spicule pigmentation, narrowing of the visual fields and retinal atrophy.

There are over 60 genes and hundreds of mutations that cause RP. Autosomal dominant RP (adRP), accounts for 15-25% of RP. Autosomal recessive RP (arRP) accounts for 5-20% of RP. X-linked RP (X-LRP) accounts for 5-15% of RP (Daiger 2007). In general, adRP often has the latest presentation, arRP has a moderate presentation and X-LRP has the earliest presentation. Autosomal-dominant retinitis pigmentosa (adRP) is caused by heterozygous mutations in the rhodopsin (RHO) gene. Mutations in the RHO gene account for 25-30% of cases of adRP.

The RHO gene encodes the rhodopsin protein. Rhodopsin is a G protein-coupled receptor expressed in the outer segment of retinal photoreceptor (PR) rod cells and is a critical element of the phototransduction cascade. Light absorbed by rhodopsin causes 11-cis retinal to isomerize into all-trans retinal. This conformational change allows rhodopsin to couple with transducin, which is the first step in the visual signaling cascade. Heterozygous mutations in the RHO gene cause a decreased production of wild-type rhodopsin and/or expression of mutant rhodopsin. This leads to poor function of the phototransduction cascade and declining function in rod PR cells. Over time, there is atrophy of rod PR cells and eventually atrophy of cone PR cells as well. This causes the typical phenotypic progression of cumulative vision loss experienced by RP subjects. Subjects with RHO mutations experience progressive loss of peripheral visual fields followed by loss of central visual fields (the latter measured by decreases in visual acuity).

Exemplary RHO mutations are provided in Table A.

Table A: RHO Mutations (Group A Mutations)

Treatment for RP is limited and there is currently no approved treatment that substantially reverses or halts the progression of disease in adRP. In an embodiment, Vitamin A supplementation may delay onset of disease and slow progression. The Argus II retinal implant was approved for use in the United States in 2013. The Argus II retinal implant is an electrical implant that offers minimal improvement in vision in subjects with RP. For example, the best visual acuity achieved in trials by the device was 20/1260. However, legal blindness is defined as 20/200 vision. Overview

As provided herein, the inventors have designed a therapeutic strategy that provides an alteration that comprises disrupting the mutant RHO gene by the insertion or deletion of one or more nucleotides mediated by an RNA-guided nuclease (e.g., Cas9 or Cpfl) as described below and providing a functional RHO cDNA. This type of alteration is also referred to as “knocking out” the mutant RHO gene and results in a loss of function of the mutant RHO gene. While not wishing to be bound by theory, knocking out the mutant RHO gene and providing a functional exogenous RHO cDNA maintains appropriate levels of rhodopsin protein in PR rod cells. This therapeutic strategy has the benefit of disrupting all known mutant alleles related to adRP, for example, the RHO mutations in Table A.

Provided herein in certain embodiments are methods of treating retinitis pigmentosa (RP) in a subject in need thereof comprising administering to the subject a composition comprising: a first nucleic acid comprising a sequence encoding an RNA-guided nuclease; and a second nucleic acid comprising a sequence encoding a first guide RNA (gRNA) comprising a first targeting domain that is complementary to a target domain in the RHO gene; and a RHO complementary DNA (cDNA). In certain embodiments, the RNA-guided nuclease may comprise an RNA-guided nuclease set forth in Table 4. In certain embodiments, the RNA-guided nuclease may be a Cas9. In certain embodiments, the Cas9 may be an S. aureus Cas9 (SaCas9). In certain embodiments, the sequence encoding the Cas9 may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NO: 1008. In certain embodiments, the Cas9 may comprise a nickase. In certain embodiments, the sequence encoding the RNA-guided nuclease may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with an RNA-guided nuclease in Table 4. In certain embodiments, the first nucleic acid may comprise a promoter operably linked to the sequence that encodes the RNA-guided nuclease. In certain embodiments, the promoter operably linked to the sequence that encodes the RNA- guided nuclease may comprise a promoter selected from the group consisting of RHO, CMV, EFS, GRK1, CRX, NRL, and RCVRN promoter. In certain embodiments, the promoter operably linked to the sequence that encodes the RNA-guided nuclease may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5,

6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:43-50, 1004. In certain embodiments, the first nucleic acid may comprise a 3’ untranslated region (UTR) nucleotide sequence downstream of the sequence encoding the RNA-guided nuclease. In certain embodiments, the 3’ UTR nucleotide sequence may comprise a RHO gene 3’ UTR nucleotide sequence. In certain embodiments, the 3’ UTR nucleotide sequence may comprise an a-globin 3’ UTR nucleotide sequence. In certain embodiments, the 3’ UTR nucleotide sequence may comprise a b-globin 3’ UTR nucleotide sequence. In certain embodiments, the 3’ UTR nucleotide sequence may comprise one or more truncations at a 5’ end of the 3’ UTR nucleotide sequence, at a 3’ end of the 3’ UTR nucleotide sequence, or both. In certain embodiments, the 3’ UTR nucleotide sequence may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:38-42, or 56. In certain embodiments, the first nucleic acid may comprise a 5’ inverted terminal repeat (ITR) sequence. In certain embodiments, the 5’ ITR sequence may comprise, or consist of, a nucleotide sequence that is the same as, or may differ by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or may share at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:59-67,

92, or 1011. In certain embodiments, the first nucleic acid may comprise a 3’ ITR sequence. In certain embodiments, the 3’ ITR sequence may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:68-76, or 93. In certain embodiments, the first nucleic acid may comprise one or more polyadenylation (poly A) sequences. In certain embodiments, the polyA sequence may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:56, 57, or 58. In certain embodiments, the first nucleic acid may comprise a SV40 intron sequence. In certain embodiments, the SV40 intron sequence may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NO:94. In certain embodiments, the first nucleic acid may comprise: (i) a 5 ’ ITR, (ii) a promoter operably linked to the sequence that encodes the RNA-guided nuclease, (iii) a SV40 intron sequence, (iv) a sequence encoding the RNA- guided nuclease; (v) one or more polyA sequences; and (vi) a 3’ ITR. In certain embodiments, the first nucleic acid may comprise: (i) a 5’ ITR, (ii) a promoter operably linked to the sequence that encodes the RNA-guided nuclease, (iii) a SV40 intron sequence, (iv) a sequence encoding the RNA-guided nuclease; (v) a 3’ UTR; (vi) one or more polyA sequences; and (vii) a 3’ ITR. In certain embodiments, the first nucleic acid may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4,

5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:9, 10, 1005, or 1009. In certain embodiments, the first targeting domain may comprise a sequence that is the same as, or differs by no more than 3 nucleotides from, a first targeting domain sequence set forth in any of SEQ ID NOs: 100-502.

In certain embodiments, the second nucleic acid may further comprise a sequence encoding a second gRNA comprising a second targeting domain that is complementary to a target domain in the RHO gene. In certain embodiments, the second targeting domain may comprise a sequence that is the same as, or differs by no more than 3 nucleotides from, a second targeting domain sequence set forth in any of SEQ ID NOs: 100-502. In certain embodiments, the first and second gRNA targeting domains comprise different sequences. In certain embodiments, the first and second gRNA targeting domains comprise the same sequence. In certain embodiments, the first targeting domain may comprise or consist of 17 to 26 nucleotides, 18 to 26 nucleotides, 19 to 26 nucleotides, 20 to 26 nucleotides, 21 to 26 nucleotides, 22 to 26 nucleotides, 23 to 26 nucleotides, 24 to 26 nucleotides, 25 to 26 nucleotides, 17 to 25 nucleotides, 18 to 25 nucleotides, 19 to 25 nucleotides, 20 to 25 nucleotides, 21 to 25 nucleotides, 22 to 25 nucleotides, 23 to 25 nucleotides, 24 to 25 nucleotides, 17 to 24 nucleotides, 18 to 24 nucleotides, 19 to 24 nucleotides, 20 to 24 nucleotides, 21 to 24 nucleotides, 22 to 24 nucleotides, 23 to 24 nucleotides, 17 to 23 nucleotides, 18 to 23 nucleotides, 19 to 23 nucleotides, 20 to 23 nucleotides, 21 to 23 nucleotides, 22 to 23 nucleotides, 17 to 22 nucleotides, 18 to 22 nucleotides, 19 to 22 nucleotides, 20 to 22 nucleotides, 21 to 22 nucleotides, 17 to 21 nucleotides, 18 to 21 nucleotides, 19 to 21 nucleotides, 20 to 21 nucleotides, 17 to 20 nucleotides, 18 to 20 nucleotides, 19 to 20 nucleotides, 17 to 19 nucleotides, 18 to 19 nucleotides, or 17 to 18 nucleotides. In certain embodiments, the second targeting domain may comprise or consist of 17 to 26 nucleotides, 18 to 26 nucleotides, 19 to 26 nucleotides, 20 to 26 nucleotides, 21 to 26 nucleotides, 22 to 26 nucleotides, 23 to 26 nucleotides, 24 to 26 nucleotides, 25 to 26 nucleotides, 17 to 25 nucleotides, 18 to 25 nucleotides, 19 to 25 nucleotides, 20 to 25 nucleotides, 21 to 25 nucleotides, 22 to 25 nucleotides, 23 to 25 nucleotides, 24 to 25 nucleotides, 17 to 24 nucleotides, 18 to 24 nucleotides, 19 to 24 nucleotides, 20 to 24 nucleotides, 21 to 24 nucleotides, 22 to 24 nucleotides, 23 to 24 nucleotides, 17 to 23 nucleotides, 18 to 23 nucleotides, 19 to 23 nucleotides, 20 to 23 nucleotides, 21 to 23 nucleotides, 22 to 23 nucleotides, 17 to 22 nucleotides, 18 to 22 nucleotides, 19 to 22 nucleotides, 20 to 22 nucleotides, 21 to 22 nucleotides, 17 to 21 nucleotides, 18 to 21 nucleotides, 19 to 21 nucleotides, 20 to 21 nucleotides, 17 to 20 nucleotides, 18 to 20 nucleotides, 19 to 20 nucleotides, 17 to 19 nucleotides, 18 to 19 nucleotides, or 17 to 18 nucleotides. In certain embodiments, the first targeting domain, the second targeting domain, or the first targeting domain and second targeting domain may comprise or consist of 22 to 26 nucleotides and may comprise a sequence selected from the group consisting of SEQ ID NOs: 101, 102, 106, 107, and 109. In certain embodiments, the first gRNA, the second gRNA, or the first gRNA and second gRNA may be a modular gRNA. In certain embodiments, the first gRNA, the second gRNA, or the first gRNA and second gRNA may be a chimeric gRNA. In certain embodiments, the first gRNA may comprise from 5’ to 3’ : a targeting domain; a first complementarity domain; a linking domain; a second complementarity domain; a proximal domain; and a tail domain.

In certain embodiments, the second gRNA comprising from 5’ to 3’: a targeting domain; a first complementarity domain; a linking domain; a second complementarity domain; a proximal domain; and a tail domain.

In certain embodiments, the first gRNA, the second gRNA, or the first gRNA and the second gRNA may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NO:88 or 90. In certain embodiments, the second nucleic acid may comprise a promoter operably linked to the sequence that encodes the first gRNA molecule. In certain embodiments, the second nucleic acid may comprise a promoter operably linked to the sequence that encodes the second gRNA molecule. In certain embodiments, the promoter operably linked to the sequence that encodes the first gRNA molecule, the second gRNA molecule, or the first gRNA molecule and second gRNA molecule may be a U6 promoter. In certain embodiments, the U6 promoter may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NO:78. In certain embodiments, the RHO cDNA may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:2, 4-7, or 13-18. In certain embodiments, the RHO cDNA molecule may not be codon modified to be resistant to hybridization with the first and second gRNA molecules. In certain embodiments, the RHO cDNA molecule may be codon modified to be resistant to hybridization with the first and second gRNA molecules. In certain embodiments, the RHO cDNA may comprise a nucleotide sequence comprising exon 1, exon 2, exon 3, exon 4, and exon 5 of the RHO gene. In certain embodiments, the RHO cDNA may comprise a nucleotide sequence comprising exon 1, intron 1, exon 2, exon 3, exon 4, and exon 5 of the RHO gene. In certain embodiments, the RHO cDNA may comprise one or more introns. In certain embodiments, the one or more introns may comprise one or more truncations at a 5 ’ end of the intron, a 3 ’ end of the intron, or both. In certain embodiments, intron 1 may comprise one or more truncations at a 5’ end of intron 1, a 3’ end of intron 1, or both. In certain embodiments, the second nucleic acid may comprise a 3’ untranslated region (UTR) nucleotide sequence downstream of the RHO cDNA. In certain embodiments, the 3’ UTR nucleotide sequence comprises a RHO gene 3’ UTR nucleotide sequence. In certain embodiments, the 3’ UTR nucleotide sequence may comprise an a- globin 3’ UTR nucleotide sequence. In certain embodiments, the 3’ UTR nucleotide sequence may comprise a b-globin 3’ UTR nucleotide sequence. In certain embodiments, the 3’ UTR nucleotide sequence may comprise one or more truncations at a 5’ end of the 3’ UTR nucleotide sequence, a 3’ end of the 3’ UTR nucleotide sequence, or both. In certain embodiments, the 3’ UTR nucleotide sequence may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:38-42, or 56. In certain embodiments, the second nucleic acid may comprise a promoter operably linked to the RHO cDNA molecule. In certain embodiments, the promoter operably linked to the RHO cDNA molecule may be a rod-specific promoter. In certain embodiments, the rod-specific promoter may be a human RHO promoter. In certain embodiments, the human RHO promoter may comprise an endogenous RHO promoter. In certain embodiments, the promoter operably linked to the RHO cDNA molecule may comprise a promoter selected from the group consisting of RHO, CMV, EFS, GRK1, CRX, NRL, and RCVRN promoter. In certain embodiments, the promoter operably linked to the RHO cDNA molecule may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:43-50, or 1004. In certain embodiments, the second nucleic acid may comprise a 5’ ITR sequence. In certain embodiments, the 5’ ITR sequence may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%,

90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:59-67, 92, or 1011. In certain embodiments, the second nucleic acid may comprise a 3’ ITR sequence. In certain embodiments, the 3’ ITR sequence may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:68-76, or 93. In certain embodiments, the second nucleic acid may comprise one or more polyadenylation (poly A) sequences. In certain embodiments, the polyA sequence may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:56, 57, or 58. In certain embodiments, the second nucleic acid may comprise a SV40 intron sequence. In certain embodiments, the SV40 intron sequence may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NO:94. In certain embodiments, the second nucleic acid may comprise (i) a 5’ ITR sequence, (ii) a promoter operably linked to the sequence that encodes the first gRNA molecule, (iii) the sequence that encodes the first gRNA molecule, (iv) a promoter operably linked to the RHO cDNA molecule, (v) a SV40 intron sequence, (vi) the RHO cDNA, (vii) a 3’ UTR sequence, (viii) one or more polyA sequences, and (ix) a 3’ ITR sequence. In certain embodiments, the second nucleic acid may comprise (i) a 5 ’ ITR sequence, (ii) a promoter operably linked to the sequence that encodes the first gRNA molecule, (iii) the sequence that encodes the first gRNA molecule, (iv) a promoter operably linked to the sequence that encodes the second gRNA molecule, (v) the sequence that encodes the second gRNA molecule, (vi) a promoter operably linked to the RHO cDNA molecule, (vii) a SV40 intron sequence, (viii) the RHO cDNA, (ix) a 3’ UTR sequence, (x) one or more polyA sequences, and (xi) a 3’ ITR sequence. In certain embodiments, the second nucleic acid may comprise the sequence that encodes the first gRNA molecule, the RHO cDNA, and one or more of the sequences selected from the group consisting of a promoter operably linked to the sequence that encodes the first gRNA molecule, the sequence that encodes the second gRNA molecule, a promoter operably linked to the sequence that encodes the second gRNA molecule, a 5 ’ ITR sequence, a promoter operably linked to the RHO cDNA molecule, a SV40 intron sequence, a 3 ’ UTR sequence, one or more polyA sequences, and a 3 ’ ITR sequence.

In certain embodiments, the second nucleic acid may comprise, or consist of, a nucleotide sequence that is the same as, or differs by no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides from, or shares at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% or greater sequence identity with SEQ ID NOs:8, 11, 1006, 1010. In certain embodiments, the first nucleotide sequence may be a first viral vector, the second nucleotide sequence may be a second viral vector, or the first nucleotide sequence may be a first viral vector and the second nucleotide sequence may be a second viral vector.

In certain embodiments, the first and second viral vectors may be selected from the group consisting of an AAV vector, an adenovirus vector, a vaccinia virus vector, and a herpes simplex virus vector. In certain embodiments, the AAV vector may be an AAV5 vector.

In certain embodiments, the 5’ UTR region (e.g., 5’ UTR, exon 1, exon 2, intron 1, exon 1/intron 1, or exon 2/intron 1 border) of a mutant RHO gene, is targeted to alter (i.e., knockout (e.g., eliminate expression of)) the mutant RHO gene.

In certain embodiments, the coding region (e.g., an exon, e.g., an early coding region) of the mutant RHO gene, is targeted to alter (i.e., knockout (e.g., eliminate expression of)) the mutant RHO gene. For example, the early coding region of the mutant RHO gene includes the sequence immediately following a start codon, within a first exon of the coding sequence, or within 500 bp of the start codon (e.g., less than 500, 450, 400, 350, 300, 250, 200, 150, 100 or 50 bp).

In certain embodiments, a non-coding region of the mutant RHO gene (e.g., an enhancer region, a promoter region, an intron, 5’ UTR, 3 ’UTR, polyadenylation signal) is targeted to alter (i.e., knockout (e.g., eliminate expression of)) the mutant RHO gene.

In certain embodiments, an exon/intron border of the mutant RHO gene (e.g., exon 1/intron 1, exon 2/intron 1) is targeted to alter (i.e., knockout (e.g., eliminate expression of)) the mutant RHO gene. In certain embodiments, targeting an exon/intron border provides the benefit of being able to use an exogenous RHO cDNA molecule that is not codon-modified to be resistant to cutting by a gRNA.

Fig. 1 shows a schematic of one embodiment of a therapeutic strategy to knockout an endogenous RHO gene and provide an exogenous RHO cDNA. In one embodiment, CRISPR/RNA-guided nuclease genome editing systems may be used to alter (i.e., knockout (e.g., eliminate expression of)) exon 1 or exon 2 of the RHO gene. In certain embodiments, the RHO gene may be mutated RHO gene. In certain embodiments, the mutated RHO gene may comprise one or more RHO mutations in Table A. Alteration of exon 1 or exon 2 of the RHO gene results in disruption of the endogenous mutated RHO gene.

In certain embodiments, the therapeutic strategy may be accomplished using a dual vector system. In certain aspects, the disclosure focuses on AAV vectors encoding CRISPR/RNA-guided nuclease genome editing systems and a replacement RHO cDNA, and on the use of such vectors to treat adRP disease. Exemplary vector genomes are schematized in Fig. 2, which illustrates certain fixed and variable elements of these vectors: inverted terminal repeats (ITRs), at least one gRNA sequence and a promoter sequences to drive its expression, an RNA-guided nuclease (e.g., Cas9) coding sequence and another promoter to drive its expression, nuclear localization signal (NLS) sequences, and a RHO cDNA sequence and another promoter to drive its expression. Each of these elements is discussed in detail herein. Additional exemplary vector genomes are schematized in Fig. 3, which illustrates certain fixed and variable elements of these vectors: at least one gRNA sequence and a promoter sequence to drive its expression (e.g., U6 promoter), an RNA-guided nuclease (e.g., S. aureus Cas9) coding sequence and another promoter to drive its expression (e.g., minimal RHO promoter), and a RHO cDNA sequence and another promoter to drive its expression (e.g., minimal RHO promoter). Additional exemplary vectors and sequences for use with the strategies described herein are set forth in Figs. 16-18 and SEQ ID NOs:8-ll, 1005, and 1006.

In certain embodiments, the AAV vector used herein may be a self-limiting vector system as described in WO2018/106693, published on June 14, 2018, and entitled Systems and Methods for One-Shot guide RNA (ogRNA) Targeting of Endogenous and Source DNA, the entire contents of which are incorporated herein by reference.

As shown in Fig. 1, in certain embodiments, a dual vector system may be used to knockout expression of mutant RHO gene and deliver an exogenous RHO cDNA to restore expression of wild-type rhodopsin protein. In certain embodiments, one AAV vector genome may comprise ITRs and an RNA-guided nuclease coding sequence and promoter sequence to drive its expression and one or more NLS sequences. In certain embodiments, a second AAV vector genome may comprise ITRs, a RHO cDNA sequence and a promoter to drive its expression, one gRNA sequence and promoter sequence to drive its expression.

While not wishing to be bound by theory, knocking out the RHO gene and replacing it with functional exogenous RHO cDNA maintains appropriate levels of rhodopsin protein in PR rod cells. Restoring appropriate levels of functional rhodopsin protein in rod PR cells maintains the phototransduction cascade and may delay or prevent PR cell death in subjects with adRP.

In some embodiments, a method disclosed herein is characterized by knocking out a variant of the RHO gene that is associated with adRP, e.g., a RHO mutant gene or allele described herein, and restoring wild-type RHO protein expression in a subject in need thereof, e.g., in a subject suffering from or predisposed to adRP. For example, in some embodiments, the methods provided herein are characterized by knocking out a mutant RHO allele in a subject having a mutant and a wild-type RHO allele, and restoring expression of wild-type rhodopsin protein in rod PR cells. In some embodiments, such methods feature knocking out the mutant allele while leaving the wild-type allele intact. In other embodiments, such methods feature knocking out both the mutant and the wild-type allele.

In some embodiments, the methods are characterized by knocking out a mutant allele of the RHO gene and providing an exogenous wild-type protein, e.g., via expression of a cDNA encoding wild-type RHO protein. In some embodiments, knocking out expression of a mutant allele (and, optionally, a wild- type allele), and restoring wild-type RHO protein expression, e.g., via expression of an exogenous RHO cDNA, in a subject in need thereof, e.g., a subject suffering from or predisposed to adRP, ameliorates at least one symptom associated with adRP. In some embodiments, such an amelioration includes, for example, improving the subject’s vision. In some embodiments, such an amelioration includes, for example, delaying adRP disease progression, e.g., as compared to an expected progression without clinical intervention. In some embodiments, such an amelioration includes, for example, arresting adRP disease progression. In some embodiments, such an amelioration includes, for example, preventing or delaying the onset of adRP disease in a subject.

In an embodiment, a method described herein comprises treating allogenic or autologous retinal cells ex vivo. In an embodiment, ex vivo treated allogenic or autologous retinal cells are introduced into the subject.

In an embodiment, a method described herein comprises treating an embryonic stem cell, an induced pluripotent stem cell or a cell derived from an iPS cell, a hematopoietic stem cell, a neuronal stem cell or a mesenchymal stem cell ex vivo. In an embodiment, ex vivo treated embryonic stem cells, induced pluripotent stem cells, hematopoietic stem cells, neuronal stem cells or a mesenchymal stem cells are introduced into the subject. In an embodiment, the cell is an induced pluripotent stem cells (iPS) cell or a cell derived from an iPS cell, e.g., an iPS cell generated from the subject, modified to knock out one or more mutated RHO genes and express functional exogenous RHO DNA and differentiated into a retinal progenitor cell or a retinal cell, e.g., retinal photoreceptor cell, and injected into the eye of the subject, e.g., subretinally, e.g., in the submacular region of the retina.

In an embodiment, a method described herein comprises treating autologous stem cells ex vivo. In an embodiment, ex vivo treated autologous stem cells are returned to the subject.

In an embodiment, the subject is treated in vivo, e.g., by a viral (or other mechanism) that targets cells from the eye (e.g., a retinal cell, e.g., a photoreceptor cell, e.g., a cone photoreceptor cell, e.g., a rod photoreceptor cell, e.g., a macular cone photoreceptor cell).

In an embodiment, the subject is treated in vivo, e.g., by a viral (or other mechanism) that targets a stem cell (e.g., an embryonic stem cell, an induced pluripotent stem cell or a cell derived from an iPS cell, a hematopoietic stem cell, a neuronal stem cell or a mesenchymal stem cell).

In an embodiment, treatment is initiated in a subject prior to disease onset. In a particular embodiment, treatment is initiated in a subject who has tested positive for one or more mutations in the RHO gene.

In an embodiment, treatment is initiated in a subject after disease onset.

In an embodiment, treatment is initiated in an early stage of adRP disease. In an embodiment, treatment is initiated after a subject presents with gradually declining vision. In an embodiment, repair of the RHO gene after adRP onset but early in the disease course will prevent progression of the disease.

In an embodiment, treatment is initiated in a subject in an advanced stage of disease. While not wishing to be bound by theory, it is held that advanced stage treatment will likely preserve a subject’s visual acuity (in the central visual field), which is important for subject function and performance of activities of daily living.

In an embodiment, treatment of a subject prevents disease progression. While not wishing to be bound by theory, it is held that initiation of treatment for subjects at all stages of disease (e.g., prophylactic treatment, early stage adRP, and advanced stage adRP) will prevent RP disease progression and be of benefit to subjects. In an embodiment, treatment is initiated after determination that the subject, e.g., an infant or newborn, teenager, or adult, is positive for a mutation in the RHO gene, e.g., a mutation described herein.

In an embodiment, treatment is initiated after determination that the subject is positive for a mutation in the RHO gene, e.g., a mutation described herein, but prior to manifestation of a symptom of the disease.

In an embodiment, treatment is initiated after determination that the subject is positive for a mutation in the RHO gene, e.g., a mutation described herein, and after manifestation of a symptom of the disease.

In an embodiment, treatment is initiated in a subject at the appearance of a decline in visual fields.

In an embodiment, treatment is initiated in a subject at the appearance of declining peripheral vision.

In an embodiment, treatment is initiated in a subject at the appearance of poor night vision and/or night blindness.

In an embodiment, treatment is initiated in a subject at the appearance of progressive visual loss.

In an embodiment, treatment is initiated in a subject at the appearance of progressive constriction of the visual field.

In an embodiment, treatment is initiated in a subject at the appearance of one or more indications consistent with adRP upon examination of a subject. Exemplary indications include, but are not limited to, bone spicule pigmentation, narrowing of the visual fields, retinal atrophy, attenuated retinal vasculature, loss of retinal pigment epithelium, pallor of the optic nerve, and/or combinations thereof.

In an embodiment, a method described herein comprises subretinal injection, submacular injection, suprachoroidal injection, or intravitreal injection, of gRNA or other components described herein, e.g., an RNA-guided nuclease (e.g., Cas9 or Cpfl molecule) and a RHO cDNA molecule.

In an embodiment, a gRNA or other components described herein, e.g., an RNA- guided nuclease (e.g., Cas9 or Cpfl molecule) and a RHO cDNA molecule are delivered, e.g., to a subject, by AAV, lentivirus, nanoparticle, or parvovirus, e.g., a modified parvovirus designed to target cells from the eye (e.g., a retinal cell, e.g., a photoreceptor cell, e.g., a cone photoreceptor cell, e.g., a rod photoreceptor cell, e.g., a macular cone photoreceptor cell). In an embodiment, a gRNA or other components described herein, e.g., an RNA- guided nuclease (e.g., Cas9 or Cpfl molecule) and a RHO cDNA molecule are delivered, e.g., to a subject, by AAV, lentivirus, nanoparticle, or parvovirus, e.g., a modified parvovirus designed to target stem cells (e.g., an embryonic stem cell, an induced pluripotent stem cell or a cell derived from an iPS cell, a hematopoietic stem cell, a neuronal stem cell or a mesenchymal stem cell).

In an embodiment, a gRNA or other components described herein, e.g., an RNA- guided nuclease (e.g., Cas9 or Cpfl molecule) and a RHO cDNA molecule are delivered, ex vivo, by electroporation.

In an embodiment, CRISPR/RNA-guided nuclease components are used to knock out the mutant RHO gene which gives rise to the disease.

I. gRNA Molecules

The terms guide RNA and gRNA refer to any nucleic acid that promotes the specific association (or “targeting”) of an RNA-guided nuclease such as a Cas9 or a Cpfl to a target sequence such as a genomic or episomal sequence in a cell. gRNAs can be uni molecular (comprising a single RNA molecule, and referred to alternatively as chimeric), or modular (comprising more than one, and typically two, separate RNA molecules, such as a crRNA and a tracrRNA, which are usually associated with one another, for example by duplexing). gRNAs and their component parts are described throughout the literature (see, e.g., Briner 2014, which is incorporated by reference; see also Cotta-Ramusino).

In bacteria and archea, type II CRISPR systems generally comprise an RNA-guided nuclease protein such as Cas9, a CRISPR RNA (crRNA) that includes a 5’ region that is complementary to a foreign sequence, and a trans-activating crRNA (tracrRNA) that includes a 5’ region that is complementary to, and forms a duplex with, a 3’ region of the crRNA. While not intending to be bound by any theory, it is thought that this duplex facilitates the formation of — and is necessary for the activity of — the RNA-guided nuclease/gRNA complex. As type II CRISPR systems were adapted for use in gene editing, it was discovered that the crRNA and tracrRNA could be joined into a single unimolecular or chimeric gRNA, for example by means of a four nucleotide (e.g., GAAA) “tetraloop” or “linker” sequence bridging complementary regions of the crRNA (at its 3 ’ end) and the tracrRNA (at its 5 ’ end) (Mali 2013; Jiang 2013; Jinek 2012; all incorporated by reference herein).

Guide RNAs, whether unimolecular or modular, include a targeting domain that is fully or partially complementary to the target domain within a target sequence (e.g., a double- stranded DNA sequence in the genome of a cell where editing is desired). In certain embodiments, a RHO target sequence encompasses, comprises, or is proximal to a RHO target position. Targeting domains are referred to by various names in the literature, including without limitation “guide sequences” (Hsu 2013, incorporated by reference herein), “complementarity regions” (Cotta-Ramusino), “spacers” (Briner 2014), and generically as “crRNAs” (Jiang 2013). Irrespective of the names they are given, targeting domains are typically 10-30 nucleotides in length, preferably 16-24 nucleotides in length (for example, 16, 17, 18, 19, 20, 21, 22, 23 or 24 nucleotides in length), and are at or near the 5’ terminus of in the case of a Cas9 gRNA, and at or near the 3’ terminus in the case of a Cpfl gRNA. The nucleic acid sequence complementary to the target domain, i.e., the nucleic acid sequence on the complementary DNA strand of the double-stranded DNA that comprises the target domain, is referred to herein as the “protospacer.”

The “protospacer-adjacent motif’ (PAM) sequence takes its name from its sequential relationship to the “protospacer” sequence. Together with protospacer sequences, PAM sequences define target sequences and/or target positions for specific RNA-guided nuclease/gRNA combinations. Various RNA-guided nucleases may require different sequential relationships between PAMs and protospacers.

For example, in general, Cas9 nucleases recognize PAM sequences that are 3 ’ of the protospacer:

5'- [ protospacer ][PAM]- 3'

3'- [ target domain ]- 5'

For another example, in general, Cpfl recognizes PAM sequences that are 5’ of the protospacer:

5'- [PAM][ protospacer ]- 3'

3 - [ target domain ]- 5'

In some embodiments described herein, RHO protospacers and exemplary suitable targeting domains are described. Those of ordinary skill in the art will be aware of additional suitable guide RNA targeting domains that can be used to target an RNA-guided nuclease to a given protospacer, e.g., targeting domains that comprise additional or less nucleotides, or that comprise one or more nucleotide mismatches when hybridized to a target domain.

In addition to the targeting domains, gRNAs typically (but not necessarily, as discussed below) include a plurality of domains that influence the formation or activity of gRNA/Cas9 complexes. For example, as mentioned above, the duplexed structure formed by first and secondary complementarity domains of a gRNA (also referred to as a repeat: anti- repeat duplex) interacts with the recognition (REC) lobe of Cas9 and may mediate the formation of Cas9/gRNA complexes (Nishimasu 2014; Nishimasu 2015; both incorporated by reference herein). It should be noted that the first and/or second complementarity domains can contain one or more poly- A tracts, which can be recognized by RNA polymerases as a termination signal. The sequence of the first and second complementarity domains are, therefore, optionally modified to eliminate these tracts and promote the complete in vitro transcription of gRNAs, for example through the use of A-G swaps as described in Briner 2014, or A-U swaps. These and other similar modifications to the first and second complementarity domains are within the scope of the present disclosure.

Along with the first and second complementarity domains, Cas9 gRNAs typically include two or more additional duplexed regions that are necessary for nuclease activity in vivo but not necessarily in vitro (Nishimasu 2015). A first stem-loop near the 3’ portion of the second complementarity domain is referred to variously as the “proximal domain,” (Cotta-Ramusino) “stem loop 1” (Nishimasu 2014; Nishimasu 2015) and the “nexus” (Briner 2014). One or more additional stem loop structures are generally present near the 3’ end of the gRNA, with the number varying by species: S. pyogenes gRNAs typically include two 3’ stem loops (for a total of four stem loop structures including the repeat: anti-repeat duplex), while S. aureus and other species have only one (for a total of three). A description of conserved stem loop structures (and gRNA structures more generally) organized by species is provided in Briner 2014.

Skilled artisans will appreciate that gRNAs can be modified in a number of ways, some of which are described below, and these modifications are within the scope of disclosure. For economy of presentation in this disclosure, gRNAs may be presented by reference solely to their targeting domain sequences. gRNA modifications

The activity, stability, or other characteristics of gRNAs can be altered through the incorporation of chemical and/or sequential modifications. As one example, transiently expressed or delivered nucleic acids can be prone to degradation by, e.g., cellular nucleases. Accordingly, the gRNAs described herein can contain one or more modified nucleosides or nucleotides which introduce stability toward nucleases. While not wishing to be bound by theory it is also believed that certain modified gRNAs described herein can exhibit a reduced innate immune response when introduced into a population of cells, particularly the cells of the present invention. As noted above, the term “innate immune response” includes a cellular response to exogenous nucleic acids, including single stranded nucleic acids, generally of viral or bacterial origin, which involves the induction of cytokine expression and release, particularly the interferons, and cell death.

One common 3’ end modification is the addition of a poly A tract comprising one or more (and typically 5-200) adenine (A) residues. The poly A tract can be contained in the nucleic acid sequence encoding the gRNA, or can be added to the gRNA during chemical synthesis, or following in vitro transcription using a polyadenosine polymerase (e.g., E. coli Poly(A)Polymerase). In vivo, poly-A tracts can be added to sequences transcribed from DNA vectors through the use of polyadenylation signals. Examples of such signals are provided in Maeder.

Some exemplary gRNA modifications useful in the context of the present RNA- guided nuclease technology are provided herein, and the skilled artisan will be able to ascertain additional suitable modifications that can be used in conjunction with the gRNAs and treatment modalities disclosed herein based on the present disclosure. Suitable gRNA modifications include, without limitations, those described in U.S. Patent Application No. US 2017/0073674 A1 and International Publication No. WO 2017/165862 Al, the entire contents of each of which are incorporated by reference herein.

II. Methods for Designing gRNAs

Methods for designing gRNAs are described herein, including methods for selecting, designing and validating target domains. Exemplary targeting domains are also provided herein. Targeting domains discussed herein can be incorporated into the gRNAs described herein.

Methods for selection and validation of target sites as well as off-target analyses are described, e.g., in Mali 2013; Hsu 2013; Fu 2014; Heigwer 2014; Bae 2014; Xiao 2014.

For example, a software tool can be used to optimize the choice of gRNA within a user’s target site, e.g., to minimize total off-target activity across the genome. Off target activity may be other than cleavage. For each possible gRNA choice using S. pyogenes Cas9, the tool can identify all off-target sites (preceding either NAG or NGG PAMs) across the genome that contain up to certain number (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10) of mismatched base-pairs. The cleavage efficiency at each off- target site can be predicted, e.g., using an experimentally-derived weighting scheme. Each possible gRNA is then ranked according to its total predicted off-target cleavage; the top-ranked gRNAs represent those that are likely to have the greatest on-target and the least off-target cleavage. Other functions, e.g., automated reagent design for CRISPR construction, primer design for the on-target Surveyor assay, and primer design for high-throughput detection and quantification of off-target cleavage via next-gen sequencing, can also be included in the tool.

The targeting domains discussed herein can be incorporated into the gRNAs described herein.

Exemplary Protospacers and Targeting Domains

Guide RNAs targeting various positions within the RHO gene for use with S. aureus Cas9 were identified. Following identification, the gRNAs were ranked into three tiers. The gRNAs in tier 1 were selected based on cutting in exon 1 and exon 2 of the RHO gene. Tier 1 guides exhibited > 9% editing in T-cells. For selection of tier 2 gRNAs, selection was based on cutting in the 5’ UTR of the RHO gene. Tier 2 gRNAs exhibited > 10% editing in T-cells. Tier 3 gRNAs were selected based cutting in intron 1 of the RHO gene. Tier 3 gRNAs exhibit > 10% editing in T-cells. Table 1 provides targeting domains for an exon 1 or exon 2 RHO target position in the RHO gene selected according to the first-tier parameters. The targeting domains were selected based on cutting in exon 1 or exon 2 of the RHO gene and exhibiting > 9% editing in T-cells. It is contemplated herein that the targeting domain hybridizes to the strand complementary to the target domain sequence provided through complementary base pairing. Any of the targeting domains in the table can be used with a S. aureus Cas9 molecule that gives double stranded cleavage. Any of the targeting domains in the table can be used with a S. aureus Cas9 single- stranded break nucleases (nickases).

Table 1

Table 2 provides targeting domains for a 5’UTR RHO target position in the RHO gene selected according to the second- tier parameters. The targeting domains were selected based on cutting in the 5’ UTR region of the RHO gene and exhibiting > 10% editing in T- cells. It is contemplated herein that the targeting domain hybridizes to the target domain through complementary base pairing. Any of the targeting domains in the table can be used with a S. aureus Cas9 molecule that gives double stranded cleavage. Any of the targeting domains in the table can be used with a S. aureus Cas9 single- stranded break nucleases (nickases).

Table 2

Table 3 provides targeting domains for an intron 1 RHO target position in the RHO gene selected according to the third-tier parameters. The targeting domains were selected based on cutting in intron 1 of the RHO gene and exhibiting > 10% editing in T-cells. It is contemplated herein that the targeting domain hybridizes to the target domain through complementary base pairing. Any of the targeting domains in the table can be used with a S. aureus Cas9 molecule that gives double stranded cleavage. Any of the targeting domains in the table can be used with a S. aureus Cas9 single-stranded break nucleases (nickases). Table 3 III. RNA-Guided Nucleases

RNA-guided nucleases according to the present disclosure include, without limitation, naturally-occurring Class 2 CRISPR nucleases such as Cas9, and Cpfl, as well as other nucleases derived or obtained therefrom. In functional terms, RNA-guided nucleases are defined as those nucleases that: (a) interact with (e.g., complex with) a gRNA; and (b) together with the gRNA, associate with, and optionally cleave or modify, a target region of a DNA that includes (i) a sequence complementary to the targeting domain of the gRNA and, optionally, (ii) an additional sequence referred to as a “protospacer adjacent motif,” or “PAM,” which is described in greater detail below. As the following examples will illustrate, RNA-guided nucleases can be defined, in broad terms, by their PAM specificity and cleavage activity, even though variations may exist between individual RNA-guided nucleases that share the same PAM specificity or cleavage activity. Skilled artisans will appreciate that some aspects of the present disclosure relate to systems, methods and compositions that can be implemented using any suitable RNA-guided nuclease having a certain PAM specificity and/or cleavage activity. For this reason, unless otherwise specified, the term RNA-guided nuclease should be understood as a generic term, and not limited to any particular type (e.g., Cas9 vs. Cpfl), species (e.g., S. pyogenes vs. S. aureus ) or variation (e.g., full-length vs. truncated or split; naturally-occurring PAM specificity vs. engineered PAM specificity).

Turning to the PAM sequence, this structure takes its name from its sequential relationship to the “protospacer” sequence that is complementary to gRNA targeting domains (or “spacers”). Together with protospacer sequences, PAM sequences define target regions or sequences for specific RNA-guided nuclease / gRNA combinations.

Various RNA-guided nucleases may require different sequential relationships between PAMs and protospacers. In general, Cas9s recognize PAM sequences that are 5’ of the protospacer as visualized relative to the top or complementary strand.

In addition to recognizing specific sequential orientations of PAMs and protospacers, RNA-guided nucleases generally recognize specific PAM sequences. S. aureus Cas9, for example, recognizes a PAM sequence of NNGRRT, wherein the N sequences are immediately 3’ of the region recognized by the gRNA targeting domain. S. pyogenes Cas9 recognizes NGG PAM sequences. It should also be noted that engineered RNA-guided nucleases can have PAM specificities that differ from the PAM specificities of similar nucleases (such as the naturally occurring variant from which an RNA-guided nuclease is derived, or the naturally occurring variant having the greatest amino acid sequence homology to an engineered RNA-guided nuclease). Modified Cas9s that recognize alternate PAM sequences are described below.

RNA-guided nucleases are also characterized by their DNA cleavage activity: naturally-occurring RNA-guided nucleases typically form DSBs in target nucleic acids, but engineered variants have been produced that generate only SSBs (discussed above; see also Ran 2013, incorporated by reference herein), or that do not cut at all.

The terms “RNA-guided nuclease” and “RNA-guided nuclease molecule” are used interchangeably herein. In some embodiments, the RNA-guided nuclease is an RNA-guided DNA endonuclease enzyme. In some embodiments, the RNA-guided nuclease is a CRISPR nuclease. Examples of RNA-guided nucleases suitable for use in the context of the methods, strategies, and treatment modalities provided herein are listed in Table 4 below, and the methods, compositions, and treatment modalities disclosed herein can, in some embodiments, make use of any combination of RNA-guided nucleases disclosed herein, or known to those of ordinary skill in the art.

Table 4. RNA-Guided Nucleases

In one embodiment, the RNA-guided nuclease is a Acidaminococcus sp. Cpf 1 RR variant (AsCpfl-RR). In another embodiment, the RNA-guided nuclease is a Cpfl RVR variant Exemplary suitable methods for designing targeting domains and guide RNAs, as well as for the use of the various Cas nucleases in the context of genome editing approaches, are known to those of skill in the art. Some exemplary methods are disclosed herein, and additional suitable methods will be apparent to the skilled artisan based on the present disclosure. The disclosure is not limited in this respect.

IV. RHO genomic sequence and complementary DNA sequences

The RHO genomic sequence is known to those of ordinary skill in the art. An exemplary RHO genomic sequence is provided below for ease of reference:

The RHO genomic sequence can be annotated as follows: mRNA 1..456, 2238..2406, 3613..3778, 3895..4134, 4970..6706

CDS 96..456,2238..2406, 3613..3778, 3895..4134, 4970..5080

Exemplary target domains, described in more detail elsewhere herein, are provided below in Table 5 for the purpose of illustration: Table 5

A variety of RHO cDNA sequences may be used herein. In certain embodiments, the RHO cDNA may be delivered to provide an exogenous functional RHO cDNA.

Provided below is an exemplary nucleic acid sequence of a wild-type RHO cDNA:

In certain embodiments, theRHO cDNA may be codon-optimized to increase expression. In certain embodiments, theRHO cDNA may be codon-modified to be resistant to hybridization with a gRNA targeting domain. In certain embodiments, theRHO cDNA is not codon-modified to be resistant to hybridization with a gRNA targeting domain.

Provided below are exemplary nucleic acid sequences of codon optimizedRHO cDNA:

In certain embodiments, theRHO cDNA may include a modified 5’ UTR, a modified 3’UTR, or a combination thereof. For example, in certain embodiments, theRHO cDNA may include a truncated 5’ UTR, a truncated 3’UTR, or a combination thereof. In certain embodiments, the RHO cDNA may include a 3’UTR from a known stable messenger RNA (mRNA). For example, in certain embodiments, the RHO cDNA may include a heterologous 3’-UTR downstream of the RHO coding sequence. For example, in some embodiments, the RHO cDNA may include an a-globin 3’ UTR. In certain embodiments, the RHO cDNA may include a b-globin 3’ UTR. In certain embodiments, the RHO cDNA may include one or more introns. In certain embodiments, the RHO cDNA may include a truncation of one or more introns.

Exemplary suitable heterologous 3’-UTRs that can be used to stabilize the transcript of the RHO cDNA include, but are not limited, to the following:

In certain embodiments, theRHO cDNA may include one or more introns. In certain embodiments, theRHO cDNA may include a truncation of one or more introns.

Table 6 below provides exemplary sequences ofRHO cDNA containing introns.

Table 6 V. Genome Editing Approaches

In some embodiments, the RHO gene is altered using one of the approaches discussed herein.

NHEJ-mediated knock-out of RHO

Some aspects of this disclosure provide strategies, methods, compositions, and treatment modalities that are characterized by targeting an RNA-guided nuclease, e.g., a Cas9 or Cpfl nuclease to a RHO target sequence, e.g., a target sequence described herein and/or using a guide RNA described herein, wherein the RNA-guided nuclease cuts the RHO genomic DNA at or near the RHO target sequence, resulting in NHEJ-mediated repair of the cut genomic DNA. The outcome of this NHEJ-mediated repair is typically the creation of an indel at the cut site, which in turn results in a loss-of-function of the cut RHO gene. A loss- of-function can be characterized by a decrease or a complete abolishment of expression of a gene product, e.g., in the case of the RHO gene: a RHO gene product, for example, a RHO transcript or a RHO protein, or by expression of a gene product that does not exhibit a function of the wild-type gene product. In some embodiments, a loss-of-function of the RHO gene is characterized by expression of a lower level of functional RHO protein. In some embodiments, a loss-of-function of the RHO gene is characterized by abolishment of expression of RHO protein from the RHO gene. In some embodiments, a loss-of-function of a mutant RHO gene or allele is characterized by decreased expression, or abolishment of expression, of the encoded mutant RHO protein.

As described herein, nuclease-induced non-homologous end-joining (NHEJ) can be used to introduce indels at a target position. Nuclease-induced NHEJ can also be used to remove (e.g., delete) genomic sequence including the mutation at a target position in a gene of interest.

While not wishing to be bound by theory, it is believed that, in an embodiment, the genomic alterations associated with the methods described herein rely on nuclease-induced NHEJ and the error-prone nature of the NHEJ repair pathway. NHEJ repairs a double-strand break in the DNA by joining together the two ends; however, generally, the original sequence is restored only if two compatible ends, exactly as they were formed by the double-strand break, are perfectly ligated. The DNA ends of the double-strand break are frequently the subject of enzymatic processing, resulting in the addition or removal of nucleotides, at one or both strands, prior to rejoining of the ends. This results in the presence of insertion and/or deletion (indel) mutations in the DNA sequence at the site of the NHEJ repair.

The indel mutations generated by NHEJ are unpredictable in nature; however, at a given break site certain indel sequences are favored and are over represented in the population, likely due to small regions of microhomology. The lengths of deletions can vary widely; most commonly in the 1-50 bp range, but they can easily reach greater than 100-200 bp. Insertions tend to be shorter and often include short duplications of the sequence immediately surrounding the break site. However, it is possible to obtain large insertions, and in these cases, the inserted sequence has often been traced to other regions of the genome or to plasmid DNA present in the cells.

Because NHEJ is a mutagenic process, it can also be used to delete small sequence motifs as long as the generation of a specific final sequence is not required. If a double strand break is targeted near to a specific sequence motif, the deletion mutations caused by the NHEJ repair often span, and therefore remove, the unwanted nucleotides. For the deletion of larger DNA segments, introducing two double-strand breaks, one on each side of the sequence, can result in NHEJ between the ends with removal of the entire intervening sequence. Both of these approaches can be used to delete specific DNA sequences; however, the error-prone nature of NHEJ may still produce indel mutations at the site of deletion.

Both double strand cleaving RNA-guided nucleases and single strand, or nickase, RNA-guided nucleases can be used in the methods and compositions described herein to generate break-induced indels.

Some exemplary methods featuring NHEJ-mediated knock-out of the RHO gene are provided herein, as are some exemplary suitable guide RNAs, RNA-guided nucleases, delivery methods, and other aspects related to such methods. Additional suitable methods, guide RNAs, RNA-guided nucleases, delivery methods, etc., will be apparent to those of ordinary skill in the art based on the present disclosure.

HDR Repair and Template Nucleic Acids

As described herein, in certain embodiments, nuclease-induced homology directed repair (HDR) can be used to alter a target position of a mutant RHO gene (e.g., knock out) and replace the mutant RHO gene with a wild-type RHO sequence. While not wishing to be bound by theory, it is believed that alteration of the target position occurs by homology- directed repair (HDR) with a donor template or template nucleic acid. For example, the donor template or the template nucleic acid provides for alteration of the target position. It is contemplated that a plasmid donor can be used as a template for homologous recombination. It is further contemplated that a single stranded donor template can be used as a template for alteration of the target position by alternate methods of homology directed repair (e.g., single strand annealing) between the cut sequence and the donor template. Donor template-effected alteration of a target sequence depends on cleavage by an RNA-guided nuclease molecule. Cleavage by RNA-guided nuclease molecule can comprise a double strand break or two single strand breaks.

Mutant RHO genes that can be replaced with wild-type RHO by HDR using a template nucleic acid include mutant RHO genes comprising point mutations, mutation hotspots or sequence insertions. In an embodiment, a mutant RHO gene having a point mutation or a mutation hotspot (e.g., a mutation hotspot of less than about 30 bp, e.g., less than 25, 20, 15, 10 or 5 bp) can be altered (e.g., knocked out) by either a single double-strand break or two single strand breaks. In an embodiment, a mutant RHO gene having a point mutation or a mutation hotspot (e.g., a mutation hotspot greater than about 30 bp, e.g., more than 35, 40, 45, 50, 75, 100, 150, 200, 250, 300, 400 or 500 bp) or an insertion can be altered (e.g., knocked out) by (1) a single double-strand break, (2) two single strand breaks, (3) two double stranded breaks with a break occurring on each side of the target position, or (4) four single stranded breaks with a pair of single stranded breaks occurring on each side of the target position.

Mutant RHO genes that can be altered (e.g., knocked out) by HDR and replaced with a template nucleic acid include, but are not limited to, those in Table A, such as P23, e.g., P23H or P23L, T58, e.g., T58R and P347, e.g., P347T, P347A, P347S, P347G, P347L or P347R.

Double strand break mediated alteration

In an embodiment, double strand cleavage is affected by an RNA-guided nuclease. In certain embodiments, the RNA-guided nuclease may be a Cas9 molecule having cleavage activity associated with an HNH-like domain and cleavage activity associated with anRuvC- like domain, e.g., an N-terminal RuvC-like domain, e.g., a wild type Cas9. Such embodiments require only a single gRNA.

Single strand break mediated alteration

In other embodiments, two single strand breaks, or nicks, are affected by a Cas9 molecule having nickase activity, e.g., cleavage activity associated with an HNH-like domain or cleavage activity associated with an N-terminal RuvC-like domain. Such embodiments require two gRNAs, one for placement of each single strand break. In an embodiment, the Cas9 molecule having nickase activity cleaves the strand to which the gRNA hybridizes, but not the strand that is complementary to the strand to which the gRNA hybridizes. In an embodiment, the Cas9 molecule having nickase activity does not cleave the strand to which the gRNA hybridizes, but rather cleaves the strand that is complementary to the strand to which the gRNA hybridizes.

In an embodiment, the nickase has HNH activity, e.g., a Cas9 molecule having the RuvC activity inactivated, e.g., a Cas9 molecule having a mutation at D10, e.g., the D10A mutation. D10A inactivates RuvC; therefore, the Cas9 nickase has (only) HNH activity and will cut on the strand to which the gRNA hybridizes (the complementary strand, which does not have the NGG PAM on it). In other embodiments, a Cas9 molecule having an H840, e.g., an H840A, mutation can be used as a nickase. H840A inactivates HNH; therefore, the Cas9 nickase has (only) RuvC activity and cuts on the non-complementary strand (the strand that has the NGG PAM and whose sequence is identical to the gRNA).

In an embodiment, in which a nickase and two gRNAs are used to position two single strand nicks, one nick is on the + strand and one nick is on the - strand of the target nucleic acid. The PAMs are outwardly facing. The gRNAs can be selected such that the gRNAs are separated by, from about 0-50, 0-100, or 0-200 nucleotides. In an embodiment, there is no overlap between the target domains that are complementary to the targeting domains of the two gRNAs. In an embodiment, the gRNAs do not overlap and are separated by as much as 50, 100, or 200 nucleotides. In an embodiment, the use of two gRNAs can increase specificity, e.g., by decreasing off-target binding (Ran 2013).

In an embodiment, a single nick can be used to induce HDR. It is contemplated herein that a single nick can be used to increase the ratio of HR to NHEJ at a given cleavage site.

Placement of the double strand break or a single strand break relative to the target position

The double strand break or single strand break in one of the strands should be sufficiently close to the target position such that alteration occurs. In an embodiment, the distance is not more than 50, 100, 200, 300, 350 or 400 nucleotides. While not wishing to be bound by theory, it is believed that the break should be sufficiently close to the target position such that the break is within the region that is subject to exonuclease-mediated removal during end resection. In an embodiment, in which a gRNA (unimolecular (or chimeric) or modular gRNA) and RNA-guided nuclease induce a double strand break for the purpose of inducing HDR- mediated replacement, the cleavage site is between 0-200 bp (e.g., 0-175, 0 to 150, 0 to 125,

0 to 100, 0 to 75, 0 to 50, 0 to 25, 25 to 200, 25 to 175, 25 to 150, 25 to 125, 25 to 100, 25 to 75, 25 to 50, 50 to 200, 50 to 175, 50 to 150, 50 to 125, 50 to 100, 50 to 75, 75 to 200, 75 to 175, 75 to 150, 75 to 125, 75 to 100 bp) away from the target position. In an embodiment, the cleavage site is between 0-100 bp (e.g., 0 to 75, 0 to 50, 0 to 25, 25 to 100, 25 to 75, 25 to 50, 50 to 100, 50 to 75 or 75 to 100 bp) away from the target position.

In an embodiment, in which two gRNAs (independently, unimolecular (or chimeric) or modular gRNA) complexing with Cas9 nickases induce two single strand breaks for the purpose of inducing HDR-mediated replacement, the closer nick is between 0-200 bp (e.g., 0- 175, 0 to 150, 0 to 125, 0 to 100, 0 to 75, 0 to 50, 0 to 25, 25 to 200, 25 to 175, 25 to 150, 25 to 125, 25 to 100, 25 to 75, 25 to 50, 50 to 200, 50 to 175, 50 to 150, 50 to 125, 50 to 100, 50 to 75, 75 to 200, 75 to 175, 75 to 150, 75 to 125, 75 to 100 bp) away from the target position and the two nicks will ideally be within 25-55 bp of each other (e.g., 25 to 50, 25 to 45, 25 to 40, 25 to 35, 25 to 30, 30 to 55, 30 to 50, 30 to 45, 30 to 40, 30 to 35, 35 to 55, 35 to 50, 35 to 45, 35 to 40, 40 to 55, 40 to 50, 40 to 45 bp) and no more than 100 bp away from each other (e.g., no more than 90, 80, 70, 60, 50, 40, 30, 20, 10 or 5 bp away from each other). In an embodiment, the cleavage site is between 0-100 bp (e.g., 0 to 75, 0 to 50, 0 to 25, 25 to 100, 25 to 75, 25 to 50, 50 to 100, 50 to 75 or 75 to 100 bp) away from the target position.

In one embodiment, two gRNAs, e.g., independently, unimolecular (or chimeric) or modular gRNA, are configured to position a double-strand break on both sides of a target position. In an alternate embodiment, three gRNAs, e.g., independently, unimolecular (or chimeric) or modular gRNA, are configured to position a double strand break (i.e., one gRNA complexes with a cas9 nuclease) and two single strand breaks or paired single stranded breaks (i.e., two gRNAs complex with Cas9 nickases) on either side of the target position. In another embodiment, four gRNAs, e.g., independently, unimolecular (or chimeric) or modular gRNA, are configured to generate two pairs of single stranded breaks (i.e., two pairs of two gRNAs complex with Cas9 nickases) on either side of the target position. The double strand break(s) or the closer of the two single strand nicks in a pair will ideally be within 0- 500 bp of the target position (e.g., no more than 450, 400, 350, 300, 250, 200, 150, 100, 50 or 25 bp from the target position). When nickases are used, the two nicks in a pair are within 25-55 bp of each other (e.g., between 25 to 50, 25 to 45, 25 to 40, 25 to 35, 25 to 30, 50 to 55, 45 to 55, 40 to 55, 35 to 55, 30 to 55, 30 to 50, 35 to 50, 40 to 50 , 45 to 50, 35 to 45, or 40 to 45 bp) and no more than 100 bp away from each other (e.g., no more than 90, 80, 70, 60, 50, 40, 30, 20 or 10 bp).

Length of the homology arms

The homology arm should extend at least as far as the region in which end resection may occur, e.g., in order to allow the resected single stranded overhang to find a complementary region within the donor template. The overall length could be limited by parameters such as plasmid size or viral packaging limits. In an embodiment, a homology arm does not extend into repeated elements, e.g., ALU repeats, LINE repeats.

Exemplary homology arm lengths include a least 50, 100, 250, 500, 750 or 1000 nucleotides.

Target position, as used herein, refers to a site on a target nucleic acid (e.g., the RHO gene) that is modified by a Cas9 molecule-dependent process. For example, the target position can be a modified Cas9 molecule cleavage of the target nucleic acid and template nucleic acid directed modification, e.g., alteration, of the target position. In an embodiment, a target position can be a site between two nucleotides, e.g., adjacent nucleotides, on the target nucleic acid into which one or more nucleotides is added. The target position may comprise one or more nucleotides that are altered, e.g., knocked out, by a template nucleic acid. In an embodiment, the target position is within a target domain (e.g., the sequence to which the gRNA binds). In an embodiment, a target position is upstream or downstream of a target domain (e.g., the sequence to which the gRNA binds).

A template nucleic acid, as that term is used herein, refers to a nucleic acid sequence which can be used in conjunction with an RNA-guided nuclease molecule and a gRNA molecule to alter the structure of a target position. In an embodiment, the target nucleic acid is modified to have some or all of the sequence of the template nucleic acid, typically at or near cleavage site(s). In an embodiment, the template nucleic acid is single stranded. In an alternate embodiment, the template nucleic acid is double stranded. In an embodiment, the template nucleic acid is DNA, e.g., double stranded DNA. In an alternate embodiment, the template nucleic acid is single stranded DNA. In an embodiment, the template nucleic acid is encoded on the same vector backbone, e.g. AAV genome, plasmid DNA, as the Cas9 and gRNA. In an embodiment, the template nucleic acid is excised from a vector backbone in vivo, e.g., it is flanked by gRNA recognition sequences.

In an embodiment, the template nucleic acid alters the structure of the target position by participating in a homology directed repair event. In an embodiment, the template nucleic acid alters the sequence of the target position. In an embodiment, the template nucleic acid results in the incorporation of a modified, or non-naturally occurring base into the target nucleic acid.

Typically, the template sequence undergoes a breakage-mediated or -catalyzed recombination with the target sequence. In an embodiment, the template nucleic acid includes a sequence that corresponds to a site on the target sequence that is cleaved by an eaCas9 mediated cleavage event. In an embodiment, the template nucleic acid includes a sequence that corresponds to both, a first site on the target sequence that is cleaved in a first Cas9 mediated event, and a second site on the target sequence that is cleaved in a second Cas9 mediated event.

In an embodiment, the template nucleic acid can include sequence which results in an alteration in the coding sequence of a translated sequence, e.g., one which results in the substitution of one amino acid for another in a protein product, e.g., transforming a mutant allele into a wild type allele, transforming a wild type allele into a mutant allele, and/or introducing a stop codon, insertion of an amino acid residue, deletion of an amino acid residue, or a nonsense mutation.

In other embodiments, the template nucleic acid can include sequence which results in an alteration in a non-coding sequence, e.g., an alteration in an exon or in a 5’ or 3’ non- translated or non-transcribed region. Such alterations include an alteration in a control element, e.g., a promoter, enhancer, and an alteration in a cis-acting or trans-acting control element.

A template nucleic acid having homology with a target position in the RHO gene can be used to alter the structure of a target sequence. The template sequence can be used to alter an unwanted structure, e.g., an unwanted or mutant nucleotide.

A template nucleic acid comprises the following components:

[5’ homology arm] -[replacement sequence] -[3’ homology arm].

The homology arms provide for recombination into the chromosome, thus replacing the undesired element, e.g., a mutation or signature, with the replacement sequence. In an embodiment, the homology arms flank the most distal cleavage sites.

In an embodiment, the 3’ end of the 5’ homology arm is the position next to the 5’ end of the replacement sequence. In an embodiment, the 5 ’ homology arm can extend at least 10, 20, 30, 40, 50, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1500, or 2000 nucleotides 5 ’ from the 5 ’ end of the replacement sequence. In an embodiment, the 5’ end of the 3’ homology arm is the position next to the 3’ end of the replacement sequence. In an embodiment, the 3 ’ homology arm can extend at least 10, 20, 30, 40, 50, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1500, or 2000 nucleotides 3 ’ from the 3 ’ end of the replacement sequence.

Exemplary Template Nucleic Acids

Exemplary template nucleic acids (also referred to herein as donor constructs) comprise one or more nucleotides of a RHO gene. In certain embodiments, the template nucleic acid comprises a RHO cDNA molecule. In certain embodiments, the template nucleic acid sequence may be codon modified to be resistant to hybridization with a gRNA molecule.

Table 7 below provides exemplary template nucleic acids. In an embodiment, the template nucleic acid includes the 5 ’ homology arm and the 3 ’ homology arm of a row from Table 7. In other embodiments, a 5’ homology arm from the first column can be combined with a 3’ homology arm from Table 7. In each embodiment, a combination of the 5’ and 3’ homology arms include a replacement sequence, e.g., a cytosine (C) residue.

Table 7

Examples of gRNAs in Genome Editing Methods gRNA molecules as described herein can be used with RNA-guided nuclease molecules (e.g., Cas9 or Cpfl molecules) that generate a double strand break or a single strand break to alter the sequence of a target nucleic acid, e.g., a target position or target genetic signature. The skilled artisan will be able to ascertain additional suitable gRNA molecules that can be used in conjunction with the methods and treatment modalities disclosed herein based on the present disclosure. Suitable gRNA molecules include, without limitations, those described in U.S. Patent Application No. US 2017/0073674 A1 and International Publication No. WO 2017/165862 Al, the entire contents of each of which are incorporated by reference herein.

VI. Target Cells

RNA-guided nuclease molecules (e.g., Cas9 or Cpfl molecules) and gRNA molecules, e.g., a Cas9 or Cpfl molecule/gRNA molecule complex can be used to manipulate a cell, e.g., to edit a target nucleic acid, in a wide variety of cells

In some embodiments, a cell is manipulated by editing (e.g., altering) one or more target genes, e.g., as described herein. In some embodiments, the expression of one or more target genes (e.g., one or more target genes described herein) is modulated, e.g., in vivo. In other embodiments, the expression of one or more target genes (e.g., one or more target genes described herein) is modulated, e.g., ex vivo.

The RNA-guided nuclease molecules (e.g., Cas9 or Cpfl molecules), gRNA molecules, and RHO cDNA molecules described herein can be delivered to a target cell. In an embodiment, the target cell is a cell from the eye, e.g., a retinal cell, e.g., a photoreceptor cell. In an embodiment, the target cell is a cone photoreceptor cell or cone cell. In an embodiment, the target cell is a rod photoreceptor cell or rod cell. In an embodiment, the target cell is a macular cone photoreceptor cell. In an exemplary embodiment, cone photoreceptors in the macula are targeted, i.e., cone photoreceptors in the macula are the target cells.

A suitable cell can also include a stem cell such as, by way of example, an embryonic stem cell, an induced pluripotent stem cell, a hematopoietic stem cell, a neuronal stem cell and a mesenchymal stem cell. In an embodiment, the cell is an induced pluripotent stem cells (iPS) cell or a cell derived from an iPS cell, e.g., an iPS cell generated from the subject, modified to alter (e.g., knock out) the mutant RHO gene and deliver exogenous RHO cDNA to the cell and differentiated into a retinal progenitor cell or a retinal cell, e.g., retinal photoreceptor, and injected into the eye of the subject, e.g., subretinally, e.g., in the submacular region of the retina. VII. Delivery, Formulations and Routes of Administration

The components, e.g., an RNA-guided nuclease molecule (e.g., Cas9 or Cpfl molecule), gRNA molecule, and RHO cDNA molecule can be delivered or formulated in a variety of forms, see, e.g., Tables 8-9. In an embodiment, one RNA-guided nuclease molecule (e.g., Cas9 or Cpfl molecule), one or more (e.g., 1, 2, 3, 4, or more) gRNA molecules, and the sequence of the RHO cDNA molecule are delivered, e.g., by an AAV vector. In an embodiment, the sequence encoding the RNA-guided nuclease molecule (e.g., Cas9 or Cpfl molecule), the sequence(s) encoding the one or more (e.g., 1, 2, 3, 4, or more) gRNA molecules, and the sequence of the RHO cDNA molecule are present on the same nucleic acid molecule, e.g., an AAV vector. In an embodiment, the sequence encoding the RNA-guided nuclease molecule (e.g., Cas9 or Cpfl molecule) is present on a first nucleic acid molecule, e.g., an AAV vector, and the sequence(s) encoding the one or more (e.g., 1, 2, 3, 4, or more) gRNA molecules and the sequence of the RHO cDNA molecule are present on a second nucleic acid molecule, e.g., an AAV vector. In an embodiment, the sequence encoding the RNA-guided nuclease molecule (e.g., Cas9 or Cpfl molecule) is present on a first nucleic acid molecule, e.g., an AAV vector, and the sequence(s) encoding the one or more (e.g., 1, 2, 3, 4, or more) gRNA molecules are present on a second nucleic acid molecule, e.g., an AAV vector, and the sequence of the RHO cDNA molecule is present on a third nucleic acid molecule, e.g., an AAV vector.

When an RNA-guided nuclease molecule (e.g., Cas9 or Cpfl molecule), gRNA, or RHO cDNA component is delivered encoded in DNA the DNA will typically include a control region, e.g., comprising a promoter, to effect expression. Useful promoters for RNA- guided nuclease molecule (e.g., Cas9 or Cpfl molecule) sequences include CMV, EFS, EF- la, MSCV, PGK, CAG, hGRKl, hCRX, hNRL, and hRCVRN control promoters. Useful promoters for gRNAs include HI, EF-la and U6 promoters. Useful promoters for RHO cDNA sequences include CMV, EFS, EF-la, MSCV, PGK, CAG, hGRKl, hCRX, hNRL, and hRCVRN control promoters. In certain embodiments, useful promoters for RHO cDNA and RNA-guided nuclease molecule sequences include a RHO promoter sequence. In certain embodiments, the RHO promoter sequence may be a minimal RHO promoter sequence. In certain embodiments, a minimal RHO promoter sequence may comprise the sequence set forth in SEQ ID NO:44. In some embodiments, a minimal RHO promoter comprises no more than 100 bp, no more than 200 bp, no more than 250 bp, no more than 300 bp, no more than 400 bp, no more than 500 bp, no more than 600 bp, no more than 700 bp, no more than 800 bp, no more than 900bp, or no more than 1000 bp of the endogenous RHO promoter region, e.g., the region of up to 3000 bp upstream from the RHO transcription start site. In some embodiments, the minimal RHO promoter comprises no more than 100 bp, no more than 200 bp, no more than 250 bp, no more than 300 bp, no more than 400 bp, no more than 500 bp, or no more than 600 bp of the sequence proximal to the transcription start site of the endogenous RHO gene, and the distal enhancer region of the RHO promoter, or a fragment thereof. In certain embodiments, the minimal RHO cDNA promoter may be a rod- specific promoter. In certain embodiments, the RHO cDNA promoter may be a human opsin promoter. RHO promoters, and engineered promoter variants, suitable for use in the context of the methods, compositions, and treatment modalities provided herein include, for example, those described in Pellissier 2014; and those described in International Patent Applications PCT/NL2014/050549, PCT/US2016/050809, and PCT/US2016/019725, the entire contents of each of which are incorporated by reference herein.

In an embodiment, the promoter is a constitutive promoter. In another embodiment, the promoter is a tissue specific promoter. Promoters with similar or dissimilar strengths can be selected to tune the expression of components. Sequences encoding an RNA-guided nuclease molecule can comprise a nuclear localization signal (NLS), e.g., an SV40 NLS. In an embodiment, the sequence encoding an RNA-guided nuclease molecule comprises at least two nuclear localization signals. In an embodiment, a promoter for an RNA-guided nuclease molecule, a gRNA molecule, or a RHO cDNA molecule can be, independently, inducible, tissue specific, or cell specific. To detect the expression of an RNA-guided nuclease, an affinity tag can be used. Useful affinity tag sequences include, but are not limited to, 3xFlag tag, single Flag tag, HA tag, Myc tag or HIS tag. Exemplary affinity tag sequences are disclosed in Table 12. To regulate RNA-guided nuclease expression, e.g., in mammalian cells, polyadenylation signals (poly(A) signals) can be used. Exemplary polyadenylation signals are disclosed in Table 13.

Table 8 provides examples of the form in which the components can be delivered to a target cell. Table 8

Table 9 summarizes various delivery methods for the components of an RNA-guided nuclease system, e.g., the Cas9 or Cpfl molecule component, the gRNA molecule component, and the RHO cDNA molecule component as described herein.

Table 9

Table 10 describes exemplary promoter sequences that can be used in AAV vectors for RNA-guided nuclease (e.g., Cas9 or Cpfl) expression. Table 10. RNA-Guided Nuclease Promoter Sequences

Table 11 describes exemplary promoter sequences that can be used in AAV vectors forRHO cDNA. Table 11. RHO cDNA Promoter Sequences

Table 12 describes exemplary affinity tag sequences that can be used in AAV vectors, e.g., for RNA-guided nuclease (e.g., Cas9 or Cpfl) expression. Table 12. Exemplary Affinity Tag Sequences

Table 13 describes exemplary polyadenylation (polyA) sequences that can be used in AAV vectors, e.g., for RNA-guided nuclease (e.g., Cas9 or Cpfl) expression. Table 13. Exemplary PolyA Sequences

Table 14 describes exemplary Inverted Terminal Repeat (ITR) sequences that can be used in AAV vectors. Table 14. Sequences of ITRs from Exemplary AAV Serotypes

Additional exemplary sequences for the recombinant AAV genome components described herein are provided below.

Exemplary U6 promoter sequence:

Exemplary gRNA targeting domain sequences are described herein, e.g., in Tables 1- 3, and 18.

Skilled artisans will understand that it may be advantageous in some embodiments to add a 5’ G to a gRNA targeting domain sequence, e.g., when the gRNA is driven by a U6 promoter.

Exemplary gRNA scaffold domain sequences:

Exemplary N-ter NLS nucleotide sequence:

Exemplary N-ter NLS amino acid sequence: PKKKRKV (SEQ ID NO: 82). Exemplary Cas9 nucleotide sequences as described herein.

Exemplary Cas9 amino acid sequences as described herein.

Exemplary Cpf 1 nucleotide sequences as described herein.

Exemplary Cpfl amino acid sequences as described herein. Exemplary C-ter NLS sequence: CCCAAGAAGAAGAGGAAAGTC (SEQ ID NO:83). Exemplary C-ter NLS amino acid sequence: PKKKRKV (SEQ ID NO: 84).

Exemplary poly(A) signal sequence:

TAGCAATAAAGGATCGTTTATTTTCATTGGAAGCGTGTGTTGGTTTTTTGATCAGGC GCG

(SEQ ID NO:56).

Exemplary 3xFLAG nucleotide sequence:

GACTACAAAGACCATGACGGTGATTATAAAGATCATGACATCGATTACAAGGATGAC GATGA CAAG (SEQ ID NO:86).

Exemplary 3xFLAG amino acid sequence:

DYKDHDGDYKDHDIDYKDDDDK (SEQ ID NO:51).

Exemplary spacer sequences:

CAGATCTGAATTCGGTACC (SEQ ID NO:77);

GGTACCGCTAGCGCTTAAGTCGCGATGTACGGGCCAGATATACGCGTTGA (SEQ ID NO:80);

TCCAAGCTTCGCAGGAAAGAACATGTGAGCAAAAGGCCAGCAAAAGGCGTTAACTCT AGATT TAAATGCATGCTGGGGAGAGATCT (SEQ ID NO:85);

CGACTTAGTTCGATCGAAGG (SEQ ID NO:87).

Exemplary SV40 intron sequence:

In certain aspects, the present disclosure focuses on AAV vectors encoding CRISPR/RNA-guided nuclease genome editing systems and a RHO cDNA molecule, and on the use of such vectors to treat adRP. Exemplary AAV vector genomes are schematized in Fig. 2, which illustrate certain fixed and variable elements of these vectors: a first AAV vector comprising ITRs, an RNA-guided nuclease (e.g., Cas9) coding sequence and a promoter to drive its expression, with the RNA-guided nuclease coding sequence flanked by NLS sequences; and a second AAV vector comprising ITRs, one RHO cDNA sequence and a minimal RHO promoter to drive its expression and one gRNA sequence and promoter sequences to drive its expression. Additional exemplary AAV vector genomes are also set forth in Figs. 3 and 16-18. Exemplary AAV vector genome sequences are set forth in SEQ ID NOs: 8-11. Turning first to the gRNA utilized in the nucleic acids or AAV vectors of the present disclosure, one or more gRNAs may be used to cut the 5’ region of a mutant RHO gene (e.g., 5’ UTR, exon 1, exon 2, intron 1, exon 1/intron border). In certain embodiments, cutting in the 5’ region of the mutant RHO gene results in knocking out or loss of function of the mutant RHO gene. In certain embodiments, one or more gRNAs may be used to cut the coding region of a mutant RHO gene (e.g., exon 1, exon 2, exon 3, exon 4, exon 5) or the non-coding region of a mutant RHO gene (e.g., 5’ UTR, introns, 3’ UTR). In certain embodiments, cutting in the coding region or non-coding region of the mutant RHO gene may result in knocking out or loss of function of the mutant RHO gene.

Targeting domain sequences of exemplary guides (both DNA and RNA sequences) are presented in Tables 1-3 and 18.

In some embodiments, the gRNAs used in the present disclosure may be derived from S. aureus gRNAs and can be unimolecular or modular, as described below. Exemplary DNA and RNA sequences corresponding to unimolecular S. aureus gRNAs are shown below:

It should be noted that the targeting domain can have any suitable length. gRNAs used in the various embodiments of this disclosure preferably include targeting domains of between 16 and 24 (inclusive) bases in length at their 5’ ends, and optionally include a 3’ U6 termination sequence as illustrated.

In some instances, modular guides can be used. In the exemplary unimolecular gRNA sequences above, a 5’ portion corresponding to a crRNA (underlined) is connected by a GAAA linker to a 3’ portion corresponding to a tracrRNA (double underlined). Skilled artisans will appreciate that two-part modular gRNAs can be used that correspond to the underlined and double underlined sections.

In certain embodiments, exemplary DNA and RNA sequences of the crRNA sequence are shown below:

GTTATAGTACTCTG (DNA, SEQ ID NO: 1012), GUUUUAGUACUCUG (RNA, SEQ ID NO: 1013); or

GTTATAGTACTCTG (DNA, SEQ ID NO: 1014), GUUAUAGUACUCUG (RNA, SEQ ID NO:1015).

In certain embodiments, exemplary DNA and RNA sequences of the tracrRNA sequence are shown below:

CAGAATCTACTAAAACAAGGCAAAATGCCGTGTTTATCTCGTCAACTTGTT GGCGAGATTTTTT (DNA, SEQ ID NO: 1016),

CAGAAUCUACUAAAACAAGGCAAAAUGCCGUGUUUAUCUCGUCAACUU GUU GGCG AG AUUUUUU (RNA, SEQ ID NO: 1017); or

CAGAATCTACTATAACAAGGCAAAATGCCGTGTTTATCTCGTCAACTTGTT GGCGAGATTTTTT (DNA, SEQ ID NO: 1018),

CAGAAUCUACUAUAACAAGGCAAAAUGCCGUGUUUAUCUCGUCAACUU GUU GGCG AG AUUUUUU (RNA, SEQ ID NO: 1019).

Skilled artisans will appreciate that the exemplary gRNA designs set forth herein can be modified in a variety of ways, which are described below or are known in the art; the incorporation of such modifications is within the scope of this disclosure.

Expression of the one or more gRNAs in the AAV vector may be driven by a pair of U6 promoters, such as a human U6 promoter. An exemplary U6 promoter sequence, as set forth in Maeder, is SEQ ID NO:78.

Turning next to RNA-guided nucleases, in some embodiments the RNA-guided nuclease may be a Cas9 or Cpfl protein. In certain embodiments, the Cas9 protein is S. pyogenes Cas9. In certain embodiments, the Cas9 protein is S. aureus Cas9. In further embodiments of this disclosure an Cas9 sequence is modified to include two nuclear localization sequences (NLSs) at the C- and N-termini of the Cas9 protein, and a mini- polyadenylation signal (or Poly-A sequence). Exemplary Cas9 sequences and Cpfl sequences are provided herein. These sequences are exemplary in nature and are not intended to be limiting. The skilled artisan will appreciate that modifications of these sequences may be possible or desirable in certain applications; such modifications are described below, or are known in the art, and are within the scope of this disclosure.

Skilled artisans will also appreciate that polyadenylation signals are widely used and known in the art, and that any suitable polyadenylation signal can be used in the embodiments of this disclosure. Exemplary polyadenylation signals are set forth in SEQ ID NOs:56-58.

Cas9 expression may be driven, in certain vectors of this disclosure, by one of three promoters: cytomegalovirus (CMV) (i.e., SEQ ID NO:45), elongation factor- 1 (EFS) (i.e., SEQ ID NO:46), or human g-protein receptor coupled kinase- 1 (hGRKl) (i.e., SEQ ID NO:47), which is specifically expressed in retinal photoreceptor cells. Modifications of the sequences of the promoters may be possible or desirable in certain applications, and such modifications are within the scope of this disclosure. In certain embodiments, Cas9 expression may be driven by a RHO promoter described herein (e.g., a minimum RHO Promoter (250 bp) SEQ ID NO:44).

Turning next to RHO cDNA, in some embodiments the RHO cDNA molecule may be wild-type RHO cDNA (e.g., SEQ ID NO:2). In certain embodiments, the RHO cDNA molecule may be a codon-modified cDNA to be resistant to hybridizing with a gRNA. In certain embodiments, the RHO cDNA molecule is not codon-modified to be resistant to hybridizing with a gRNA. In certain embodiments, the RHO cDNA molecule may be a codon-optimized cDNA to provide increased expression of rhodopsin protein (e.g., SEQ ID NOs:13-18). In certain embodiments, the RHO cDNA may comprise a modified 3’ UTR, for example, a 3’ UTR from a highly expressed, stable transcript, such as alpha- or beta-globin. Exemplarly 3’ UTRs are set forth in SEQ ID NOs:38-42. In certain embodiments, the RHO cDNA may include one or more introns (e.g., SEQ ID NOs:4-7). In certain embodiments, the RHO cDNA may include a truncation of one or more introns.

In certain embodiments, RHO cDNA expression may be driven by a rod-specific promoter. In certain embodiments, RHO cDNA expression may be driven by a RHO promoter described herein (e.g., a minimum RHO Promoter (250 bp) SEQ ID NO:44).

AAV genomes according to the present disclosure generally incorporate inverted terminal repeats (ITRs) derived from the AAV5 serotype. Exemplary 5’ and 3’ ITRs are SEQ ID NO:63 (AAV5 5’ ITR) and SEQ ID NO:72 (AAV5 3’ ITR), respectively. In certain embodiments, exemplary 5’ and 3’ ITRs are SEQ ID NO:92 (AAV 5’ ITR) and SEQ ID NO:93 (AAV 3’ ITR), respectively. It should be noted, however, that numerous modified versions of the AAV5 ITRs are used in the field, and the ITR sequences shown herein are exemplary and are not intended to be limiting. Modifications of these sequences are known in the art, or will be evident to skilled artisans, and are thus included in the scope of this disclosure.

The gRNA, RNA-guided nuclease, and RHO cDNA promoters are variable and can be selected from the lists presented herein. For clarity, this disclosure encompasses nucleic acids and/or AAV vectors comprising any combination of these elements, though certain combinations may be preferred for certain applications.

In various embodiments, a first nucleic acid or AAV vector may encode the following: 5’ and 3’ AAV ITR sequences (e.g., AAV5 ITRs), a promoter (e.g., CMV, hGRKl, EFS, RHO promoter) to drive expression of an RNA-guided nuclease (e.g., Cas9 encoded by a Cas9 nucleic acid molecule or Cpfl encoded by a Cpfl nucleic acid), NLS sequences flanking the RNA-guided nuclease nucleic acid molecule, and a second nucleic acid or AAV vector may encode the following: 5’ and 3’ AAV ITR sequences (e.g., AAV5 ITRs), a U6 promoter to drive expression of a guide RNA comprising a targeting domain sequence (e.g., a sequence according to a sequence in Tables 1-3 or 18), and a RHO promoter (e.g., minimal RHO promoter) to drive expression of a RHO cDNA molecule.

The nucleic acid or AAV vector may also comprise a Simian virus 40 (SV40) splice donor/splice acceptor (SD/SA) sequence element. In certain embodiments, the SV40 SD/SA element may be positioned between the promoter and the RNA-guided nuclease gene (e.g., Cas9 or Cpfl gene). In certain embodiments, a Kozak consensus sequence may precede the start codon of the RNA-guided nuclease (e.g., Cas9 or Cpfl) to ensure robust RNA-guided nuclease (e.g., Cas9 or Cpfl) expression.

In some embodiments, the nucleic acid or AAV vector shares at least 80%, 85%,

90%, 95%, 96%, 97%, 98%, 99% or greater sequence identity with one of the nucleic acids or AAV vectors recited above.

It should be noted that these sequences described above are exemplary and can be modified in ways that do not disrupt the operating principles of elements they encode. Such modifications, some of which are discussed below, are within the scope of this disclosure. Without limiting the foregoing, skilled artisans will appreciate that the DNA, RNA or protein sequences of the elements of this disclosure may be varied in ways that do not interrupt their function, and that a variety of similar sequences that are substantially similar (e.g., greater than 90%, 95%, 96%, 97%, 98% or 99% sequence similarity, or in the case of short sequences such as gRNA targeting domains, sequences that differ by no more than 1, 2 or 3 nucleotides) can be utilized in the various systems, methods and AAV vectors described herein. Such modified sequences are within the scope of this disclosure. The AAV genomes described above can be packaged into AAV capsids (for example, AAV5 capsids), which capsids can be included in compositions (such as pharmaceutical compositions) and/or administered to subjects. An exemplary pharmaceutical composition comprising an AAV capsid according to this disclosure can include a pharmaceutically acceptable carrier such as balanced saline solution (BSS) and one or more surfactants (e.g., Tween20) and/or a thermosensitive or reverse-thermosensitive polymer (e.g., pluronic). Other pharmaceutical formulation elements known in the art may also be suitable for use in the compositions described here. Compositions comprising AAV vectors according to this disclosure can be administered to subjects by any suitable means, including without limitation injection, for example, subretinal injection. The concentration of AAV vector within the composition is selected to ensure, among other things, that a sufficient AAV dose is administered to the retina of the subject, taking account of dead volume within the injection apparatus and the relatively limited volume that can be safely administered to the retina. Suitable doses may include, for example, 1x10 ¹¹ viral genomes (vg)/mL, 2x10 ¹¹ viral genomes (vg)/mL, 3x10 ¹¹ viral genomes (vg)/mL, 4x10 ¹¹ viral genomes (vg)/mL, 5x10 ¹¹ viral genomes (vg)/mL, 6x10 ¹¹ viral genomes (vg)/mL, 7x10 ¹¹ viral genomes (vg)/mL, 8x10 ¹¹ viral genomes (vg)/mL, 9x10 ¹¹ viral genomes (vg)/mL, 1x10 ¹² vg/mL, 2x10 ¹² viral genomes (vg)/mL, 3x10 ¹² viral genomes (vg)/mL, 4x10 ¹² viral genomes (vg)/mL, 5x10 ¹² viral genomes (vg)/mL, 6x10 ¹² viral genomes (vg)/mL, 7x10 ¹² viral genomes (vg)/mL, 8x10 ¹² viral genomes (vg)/mL, 9x10 ¹² viral genomes (vg)/mL, 1x10 ¹³ vg/mL, 2x10 ¹³ viral genomes (vg)/mL, 3x10 ¹³ viral genomes (vg)/mL, 4x10 ¹³ viral genomes (vg)/mL, 5x10 ¹³ viral genomes (vg)/mL, 6x10 ¹³ viral genomes (vg)/mL, 7x10 ¹³ viral genomes (vg)/mL, 8x10 ¹³ viral genomes (vg)/mL, or 9x10 ¹³ viral genomes (vg)/mL. In another embodiment, suitable doses may include 1x10 ¹¹ vg/mL to 2x10 ¹¹ vg/mL, 2x10 ¹¹ vg/mL to 3x10 ¹¹ vg/mL, 3x10 ¹¹ vg/mL to 4x10 ¹¹ vg/mL, 4x10 ¹¹ vg/mL to 5x10 ¹¹ vg/mL, 5x10 ¹¹ vg/mL to 6x10 ¹¹ vg/mL, 6x10 ¹¹ vg/mL to 7x10 ¹¹ vg/mL, 7x10 ¹¹ vg/mL to 8x10 ¹¹ vg/mL, 8x10 ¹¹ vg/mL to 9x10 ¹¹ vg/mL, 9x10 ¹¹ vg/mL to 1x10 ¹² vg/mL, 1x10 ¹² vg/mL to 2x10 ¹² vg/mL, 2x10 ¹² vg/mL to 3x10 ¹² vg/mL, 3x10 ¹² vg/mL to 4x10 ¹² vg/mL, 4x10 ¹² vg/mL to 5x10 ¹² vg/mL, 5x10 ¹² vg/mL to 6x10 ¹² vg/mL, 6x10 ¹² vg/mL to 7x10 ¹² vg/mL, 7x10 ¹² vg/mL to 8x10 ¹² vg/mL, 8x10 ¹² vg/mL to 9x10 ¹² vg/mL, 9x10 ¹² vg/mL to 1x10 ¹³ vg/mL, 1x10 ¹³ vg/mL to 2x10 ¹³ vg/mL, 2x10 ¹³ vg/mL to 3x10 ¹³ vg/mL, 3x10 ¹³ vg/mL to 4xl0 ¹³ vg/mL, 4xl0 ¹³ vg/mL to 5xl0 ¹³ vg/mL, 5xl0 ¹³ vg/mL to 6xl0 ¹³ vg/mL, 6xl0 ¹³ vg/mL to 7xl0 ¹³ vg/mL, 7xl0 ¹³ vg/mL to 8xl0 ¹³ vg/mL, or 8xl0 ¹³ vg/mL to 9xl0 ¹³ vg/mL.

Any suitable volume of the composition may be delivered to the subretinal space. In some instances, the volume is selected to form a bleb in the subretinal space, for example 1 microliter, 10 microliters, 50 microliters, 100 microliters, 150 microliters, 200 microliters,

250 microliters, 300 microliters, 350 microliter, 400 microliters, 450 microliters, 500 microliters, 550 microliters, 600 microliters, 650 microliters, 700 microliters, 750 microliters, 800 microliters, 900 microliters, 950 microliters, 1 milliliter, etc. In certain embodiments, the suitable volume to be delivered may be at least 1 microliter, at least 10 microliters, at least 50 microliters, at least 100 microliters, at least 150 microliters, at least 200 microliters, at least 250 microliters, at least 300 microliters, at least 350 microliter, at least 400 microliters, at least 450 microliters, at least 500 microliters, at least 550 microliters, at least 600 microliters, at least 650 microliters, at least 700 microliters, at least 750 microliters, at least 800 microliters, at least 900 microliters, at least 950 microliters, at least 1 milliliter, etc. In certain embodiments, the suitable volume to be delivered may be 1 microliter to 10 microliters, 10 microliters to 50 microliters, 50 microliters to 100 microliters, 100 microliters to 150 microliters, 150 microliters to 200 microliters, 250 microliters to 300 microliters, 300 microliters to 350 microliters, 400 microliters to 450 microliters, 500 microliters to 550 microliters, 600 microliters to 650 microliters, 700 microliters to 750 microliters, 800 microliters to 850 microliters, 900 microliters to 950 microliters, or 950 microliters to 1000 microliters, etc.

Any region of the retina may be targeted, though the fovea (which extends approximately 1 degree out from the center of the eye) may be preferred in certain instances due to its role in central visual acuity and the relatively high concentration of cone photoreceptors there relative to peripheral regions of the retina. Alternatively or additionally, injections may be targeted to parafoveal regions (extending between approximately 2 and 10 degrees off center), which are characterized by the presence of both rod and cone photoreceptor cells. In addition, injections into the parafoveal region may be made at comparatively acute angles using needle paths that cross the midline of the retina. For instance, injection paths may extend from the nasal aspect of the sclera near the limbus through the vitreal chamber and into the parafoveal retina on the temporal side, from the temporal aspect of the sclera to the parafoveal retina on the nasal side, from a portion of the sclera located superior to the cornea to an inferior parafoveal position, and/or from an inferior portion of the sclera to a superior parafoveal position. The use of relatively small angles of injection relative to the retinal surface may advantageously reduce or limit the potential for spillover of vector from the bleb into the vitreous body and, consequently, reduce the loss of the vector during delivery. In other cases, the macula (inclusive of the fovea) can be targeted, and in other cases, additional retinal regions can be targeted, or can receive spillover doses.

To mitigate ocular inflammation and associated discomfort, one or more corticosteroids may be administered before, during, and/or after administration of the composition comprising AAV vectors. In certain embodiments, the corticosteroid may be an oral corticosteroid. In certain embodiments, the oral corticosteroid may be prednisone. In certain embodiments, the corticosteroid may be administered as a prophylactic, prior to administration of the composition comprising AAV vectors. For example, the corticosteroid may be administered the day prior to administration, or 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, 8 days, 9 days, 10 days, 11 days, 12 days, 13 days, or 14 days prior to administration of the composition comprising AAV vectors. In certain embodiments, the corticosteroid may be administered for 1 week to 10 weeks after administration of the composition comprising AAV vectors (e.g., 1 week, 2 weeks, 3 weeks, 4 weeks, 5 weeks, 6 weeks, 7 weeks, 8 weeks, 9 weeks, or 10 weeks after administration of the composition comprising AAV vectors). In certain embodiments, the corticosteroid treatment may be administered prior to (e.g., the day prior to administration, or 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, 8 days, 9 days, 10 days, 11 days, 12 days, 13 days, or 14 days prior to administration) and after administration of the composition comprising AAV vectors (e.g., 1 week, 2 weeks, 3 weeks, 4 weeks, 5 weeks, 6 weeks, 7 weeks, 8 weeks, 9 weeks, or 10 weeks after administration). For example, the corticosteroid treatment may be administered beginning 3 days prior to until 6 weeks after administration of the AAV vector.

Suitable doses of corticosteroids may include, for example, 0.1 mg/kg/day to 10 mg/kd/day (e.g., 0.1 mg/kg/day, 0.2 mg/kg/day, 0.3 mg/kg/day, 0.4 mg/kg/day, 0.5 mg/kg/day, 0.6 mg/kg/day, 0.7 mg/kg/day, 0.8 mg/kg/day, 0.9 mg/kg/day, or 1.0 mg/kg/day). In certain embodiments, the corticosteroid may be administered at an elevated dose during the corticosteroid treatment, followed by a tapered dose of the corticosteroid. For example, 0.5 mg/kg/day corticosteroid may be administered for 4 weeks, followed by a 15-day taper (0.4 mg/kg/day for 5 days, and then 0.2 mg/kg/day for 5 days, and then 0.1 mg/kg/day for 5 days). The corticosteroid dose may be increased if there is an increase in vitreous inflammation by 1+ on the grading scale following surgery (e.g., within 4 weeks after surgery). For example, if there is an increase in vitreous inflammation by 1+ on the grading scale while the patient is receiving a 0.5 mg/kg/day dose (e.g., within 4 weeks after surgery), the corticosteroid dose may be may be increased to 1 mg/kg/day. If any inflammation is present within 4 weeks after surgery, the taper may be delayed.

For pre-clinical development purposes, systems, compositions, nucleotides and vectors according to this disclosure can be evaluated ex vivo using a retinal explant system, or in vivo using an animal model such as a mouse, rabbit, pig, nonhuman primate, etc.

Retinal explants are optionally maintained on a support matrix, and AAV vectors can be delivered by injection into the space between the photoreceptor layer and the support matrix, to mimic subretinal injection. Tissue for retinal explantation can be obtained from human or animal subjects, for example mouse.

Explants are particularly useful for studying the expression of gRNAs, RNA-guided nucleases, and rhodopsin protein following viral transduction, and for studying genome editing over comparatively short intervals. These models also permit higher throughput than may be possible in animal models and can be predictive of expression and genome editing in animal models and subjects. Small (mouse, rat) and large animal models (such as rabbit, pig, nonhuman primate) can be used for pharmacological and/or toxicological studies and for testing the systems, nucleotides, vectors and compositions of this disclosure under conditions and at volumes that approximate those that will be used in clinic. Because model systems are selected to recapitulate relevant aspects of human anatomy and/or physiology, the data obtained in these systems will generally (though not necessarily) be predictive of the behavior of AAV vectors and compositions according to this disclosure in human and animal subjects.

DNA-based Delivery of an RNA-guided nuclease molecule, a gRNA molecule, and/or a RHO expression cassette

DNA encoding RNA-guided nuclease molecules (e.g., Cas9 or Cpfl molecules), gRNA molecules, and/or RHO cDNA molecules can be administered to subjects or delivered into cells by art-known methods or as described herein. For example, RNA-guided nuclease (e.g., Cas9 or Cpfl) encoding DNA, gRNA-encoding DNA, and/or RHO cDNA can be delivered, e.g., by vectors (e.g., viral or non-viral vectors), non- vector based methods (e.g., using naked DNA or DNA complexes), or a combination thereof.

In some embodiments, the RNA-guided nuclease (e.g., Cas9 or Cpfl)-encoding DNA, gRNA-encoding DNA, and/or RHO cDNA is delivered by a vector (e.g., viral vector/vims or plasmid). A vector can comprise a sequence that encodes an RNA-guided nuclease-encoding DNA, gRNA-encoding DNA, and/or RHO cDNA molecule. A vector can also comprise a sequence encoding a signal peptide (e.g., for nuclear localization, nucleolar localization, mitochondrial localization), fused, e.g., to an RNA-guided nuclease sequence. For example, a vector can comprise a nuclear localization sequence (e.g., from SV40) fused to the sequence encoding the RNA-guided nuclease (e.g., Cas9 or Cpfl) molecule.

One or more regulatory/control elements, e.g., a promoter, an enhancer, an intron, a polyadenylation signal, a Kozak consensus sequence, internal ribosome entry sites (IRES), a 2A sequence, and splice acceptor or donor can be included in the vectors. In some embodiments, the promoter is recognized by RNA polymerase II (e.g., a CMV promoter). In other embodiments, the promoter is recognized by RNA polymerase III (e.g., a U6 promoter). In some embodiments, the promoter is a regulated promoter (e.g., inducible promoter). In other embodiments, the promoter is a constitutive promoter. In some embodiments, the promoter is a tissue specific promoter. In some embodiments, the promoter is a viral promoter. In other embodiments, the promoter is a non- viral promoter.

In some embodiments, the vector or delivery vehicle is a viral vector (e.g., for generation of recombinant viruses). In some embodiments, the vims is a DNA vims (e.g., dsDNA or ssDNA vims). In other embodiments, the vims is an RNA vims (e.g., an ssRNA virus). Exemplary viral vectors/vimses include, e.g., retroviruses, lentivimses, adenovirus, adeno-associated vims (AAV), vaccinia viruses, poxvimses, and herpes simplex vimses.

In some embodiments, the virus infects dividing cells. In other embodiments, the virus infects non-dividing cells. In some embodiments, the virus infects both dividing and non-dividing cells. In some embodiments, the virus can integrate into the host genome. In some embodiments, the virus is engineered to have reduced immunity, e.g., in human. In some embodiments, the virus is replication-competent. In other embodiments, the vims is replication-defective, e.g., having one or more coding regions for the genes necessary for additional rounds of virion replication and/or packaging replaced with other genes or deleted. In some embodiments, the virus causes transient expression of the RNA-guided nuclease molecule, the gRNA molecule, and/or the RHO cDNA molecule. In other embodiments, the virus causes long-lasting, e.g., at least 1 week, 2 weeks, 1 month, 2 months, 3 months, 6 months, 9 months, 1 year, 2 years, or permanent expression, of the RNA-guided nuclease molecule, the gRNA molecule, and/or the RHO cDNA molecule. The packaging capacity of the vimses may vary, e.g., from at least about 4 kb to at least about 30 kb, e.g., at least about 5 kb, 10 kb, 15 kb, 20 kb, 25 kb, 30 kb, 35 kb, 40 kb, 45 kb, or 50 kb. In some embodiments, the RNA-guided nuclease-encoding DNA, gRNA-encoding DNA, and/or RHO cDNA is delivered by a recombinant retrovirus. In some embodiments, the retrovirus (e.g., Moloney murine leukemia virus) comprises a reverse transcriptase, e.g., that allows integration into the host genome. In some embodiments, the retrovirus is replication-competent. In other embodiments, the retrovirus is replication-defective, e.g., having one of more coding regions for the genes necessary for additional rounds of virion replication and packaging replaced with other genes, or deleted.

In some embodiments, the RNA-guided nuclease-encoding DNA, gRNA-encoding DNA, and/or RHO cDNA is delivered by a recombinant lentivirus. For example, the lentivirus is replication-defective, e.g., does not comprise one or more genes required for viral replication.

In some embodiments, the RNA-guided nuclease-encoding DNA, gRNA-encoding DNA, and/or RHO cDNA is delivered by a recombinant adenovirus. In some embodiments, the adenovirus is engineered to have reduced immunity in human.

In some embodiments, the RNA-guided nuclease-encoding DNA, gRNA-encoding DNA, and/or RHO cDNA is delivered by a recombinant AAV. In some embodiments, the AAV can incorporate its genome into that of a host cell, e.g., a target cell as described herein. In some embodiments, the AAV is a self-complementary adeno-associated vims (scAAV), e.g., a scAAV that packages both strands which anneal together to form double stranded DNA. AAV serotypes that may be used in the disclosed methods, include AAV1, AAV2, modified AAV2 (e.g., modifications at Y444F, Y500F, Y730F and/or S662V), AAV3, modified AAV3 (e.g., modifications at Y705F, Y731F and/or T492V), AAV4, AAV5, AAV6, modified AAV6 (e.g., modifications at S663V and/or T492V), AAV8, AAV 8.2, AAV9, AAV rh 10, and pseudotyped AAV, such as AAV2/8, AAV2/5 and AAV2/6 can also be used in the disclosed methods.

In some embodiments, the RNA-guided nuclease-encoding DNA, gRNA-encoding DNA, and/or RHO cDNA is delivered by a hybrid vims, e.g., a hybrid of one or more of the viruses described herein.

A packaging cell is used to form a vims particle that is capable of infecting a host or target cell. Such a cell includes a 293 cell, which can package adenovirus, and a y2 cell or a PA317 cell, which can package retrovirus. A viral vector used in gene therapy is usually generated by a producer cell line that packages a nucleic acid vector into a viral particle. The vector typically contains the minimal viral sequences required for packaging and subsequent integration into a host or target cell (if applicable), with other viral sequences being replaced by an expression cassette encoding the protein to be expressed. For example, an AAV vector used in gene therapy typically only possesses inverted terminal repeat (ITR) sequences from the AAV genome which are required for packaging and gene expression in the host or target cell. The missing viral functions are supplied in trans by the packaging cell line. Henceforth, the viral DNA is packaged in a cell line, which contains a helper plasmid encoding the other AAV genes, namely rep and cap, but lacking ITR sequences. The cell line is also infected with adenovirus as a helper. The helper virus promotes replication of the AAV vector and expression of AAV genes from the helper plasmid. The helper plasmid is not packaged in significant amounts due to a lack of ITR sequences. Contamination with adenovirus can be reduced by, e.g., heat treatment to which adenovirus is more sensitive than AAV.

In an embodiment, the viral vector has the ability of cell type and/or tissue type recognition. For example, the viral vector can be pseudotyped with a different/altemative viral envelope glycoprotein; engineered with a cell type-specific receptor (e.g., genetic modification of the viral envelope glycoproteins to incorporate targeting ligands such as a peptide ligand, a single chain antibody, a growth factor); and/or engineered to have a molecular bridge with dual specificities with one end recognizing a viral glycoprotein and the other end recognizing a moiety of the target cell surface (e.g., ligand-receptor, monoclonal antibody, avidin-biotin and chemical conjugation).

In an embodiment, the viral vector achieves cell type specific expression. For example, a tissue-specific promoter can be constructed to restrict expression of the transgene (Cas 9 and gRNA) in only the target cell. The specificity of the vector can also be mediated by microRNA-dependent control of transgene expression. In an embodiment, the viral vector has increased efficiency of fusion of the viral vector and a target cell membrane. For example, a fusion protein such as fusion-competent hemagglutin (HA) can be incorporated to increase viral uptake into cells. In an embodiment, the viral vector has the ability of nuclear localization. For example, a virus that requires the breakdown of the cell wall (during cell division) and therefore will not infect a non-diving cell can be altered to incorporate a nuclear localization peptide in the matrix protein of the vims thereby enabling the transduction of non-proliferating cells.

In some embodiments, the RNA-guided nuclease-encoding DNA, gRNA-encoding DNA, and/or RHO cDNA is delivered by a non- vector based method (e.g., using naked DNA or DNA complexes). For example, the DNA can be delivered, e.g., by organically modified silica or silicate (Ormosil), electroporation, gene gun, sonoporation, magnetofection, lipid- mediated transfection, dendrimers, inorganic nanoparticles, calcium phosphates, or a combination thereof.

In some embodiments, the RNA-guided nuclease-encoding DNA, gRNA-encoding DNA, and/or RHO cDNA is delivered by a combination of a vector and a non- vector based method. For example, a virosome comprises a liposome combined with an inactivated virus (e.g., HIV or influenza virus), which can result in more efficient gene transfer, e.g., in a respiratory epithelial cell than either a viral or a liposomal method alone.

In an embodiment, the delivery vehicle is a non- viral vector. In an embodiment, the non- viral vector is an inorganic nanoparticle (e.g., attached to the payload to the surface of the nanoparticle). Exemplary inorganic nanoparticles include, e.g., magnetic nanoparticles (e.g., FesMnC ), or silica. The outer surface of the nanoparticle can be conjugated with a positively charged polymer (e.g., polyethylenimine, polylysine, poly serine) which allows for attachment (e.g., conjugation or entrapment) of payload. In an embodiment, the non-viral vector is an organic nanoparticle (e.g., entrapment of the payload inside the nanoparticle). Exemplary organic nanoparticles include, e.g., SNALP liposomes that contain cationic lipids together with neutral helper lipids which are coated with polyethylene glycol (PEG) and protamine and nucleic acid complex coated with lipid coating.

Exemplary lipids for gene transfer are shown below in Table 15.

Table 15: Lipids Used for Gene Transfer Exemplary polymers for gene transfer are shown below in Table 16.

Table 16: Polymers Used for Gene Transfer

In an embodiment, the vehicle has targeting modifications to increase target cell update of nanoparticles and liposomes, e.g., cell specific antigens, monoclonal antibodies, single chain antibodies, aptamers, polymers, sugars, and cell penetrating peptides. In an embodiment, the vehicle uses fusogenic and endosome-destabilizing peptides/polymers. In an embodiment, the vehicle undergoes acid-triggered conformational changes (e.g., to accelerate endosomal escape of the cargo). In an embodiment, a stimuli-cleavable polymer is used, e.g., for release in a cellular compartment. For example, disulfide-based cationic polymers that are cleaved in the reducing cellular environment can be used. In an embodiment, the delivery vehicle is a biological non-viral delivery vehicle. In an embodiment, the vehicle is an attenuated bacterium (e.g., naturally or artificially engineered to be invasive but attenuated to prevent pathogenesis and expressing the transgene (e.g., Listeria monocytogenes, certain Salmonella strains, Bifidobacterium longum, and modified Escherichia coli), bacteria having nutritional and tissue- specific tropism to target specific tissues, bacteria having modified surface proteins to alter target tissue specificity). In an embodiment, the vehicle is a genetically modified bacteriophage (e.g., engineered phages having large packaging capacity, less immunogenic, containing mammalian plasmid maintenance sequences and having incorporated targeting ligands). In an embodiment, the vehicle is a mammalian virus-like particle. For example, modified viral particles can be generated (e.g., by purification of the “empty” particles followed by ex vivo assembly of the virus with the desired cargo). The vehicle can also be engineered to incorporate targeting ligands to alter target tissue specificity. In an embodiment, the vehicle is a biological liposome. For example, the biological liposome is a phospholipid-based particle derived from human cells (e.g., erythrocyte ghosts, which are red blood cells broken down into spherical structures derived from the subject (e.g., tissue targeting can be achieved by attachment of various tissue or cell-specific ligands), or secretory exosomes -subject (i.e., patient) derived membrane-bound nanovesicle (30 -100 nm) of endocytic origin (e.g., can be produced from various cell types and can therefore be taken up by cells without the need of for targeting ligands).

In an embodiment, one or more nucleic acid molecules (e.g., DNA molecules) other than the components of an RNA-guided nuclease system, e.g., the Cas9 or Cpfl molecule component, the gRNA molecule component, and/or the RHO cDNA molecule component described herein, are delivered. In an embodiment, the nucleic acid molecule is delivered at the same time as one or more of the components of the RNA-guided nuclease system are delivered. In an embodiment, the nucleic acid molecule is delivered before or after (e.g., less than about 30 minutes, 1 hour, 2 hours, 3 hours, 6 hours, 9 hours, 12 hours, 1 day, 2 days, 3 days, 1 week, 2 weeks, or 4 weeks) one or more of the components of the RNA-guided nuclease system are delivered. In an embodiment, the nucleic acid molecule is delivered by a different means than one or more of the components of the RNA-guided nuclease system, e.g., the Cas9 or Cpfl molecule component, the gRNA molecule component, and/or the RHO cDNA molecule component are delivered. The nucleic acid molecule can be delivered by any of the delivery methods described herein. For example, the nucleic acid molecule can be delivered by a viral vector, e.g., an integration-deficient lenti virus, and the RNA-guided nuclease molecule component, the gRNA molecule component, and/or the RHO cDNA molecule component can be delivered by electroporation, e.g., such that the toxicity caused by nucleic acids (e.g., DNAs) can be reduced. In an embodiment, the nucleic acid molecule encodes a therapeutic protein, e.g., a protein described herein. In an embodiment, the nucleic acid molecule encodes an RNA molecule, e.g., an RNA molecule described herein.

Delivery of RNA encoding an RNA- guided nuclease molecule

RNA encoding RNA-guided nuclease molecules (e.g., Cas9 or Cpfl molecules described herein), gRNA molecules, and/or RHO cDNA molecules can be delivered into cells, e.g., target cells described herein, by art-known methods or as described herein. For example, RNA-guided nuclease molecules (e.g., Cas9 or Cpfl molecules described herein), gRNA molecules, and/or RHO cDNA molecules can be delivered, e.g., by microinjection, electroporation, lipid-mediated transfection, peptide-mediated delivery, or a combination thereof.

Delivery RNA-guided nuclease molecule protein

RNA-guided nuclease molecules (e.g., Cas9 or Cpfl molecules described herein) can be delivered into cells by art-known methods or as described herein. For example, RNA- guided nuclease protein molecules can be delivered, e.g., by microinjection, electroporation, lipid-mediated transfection, peptide-mediated delivery, or a combination thereof. Delivery can be accompanied by DNA encoding a gRNA and/or RHO cDNA or by a gRNA and/or RHO cDNA.

Routes of Administration

Systemic modes of administration include oral and parenteral routes. Parenteral routes include, by way of example, intravenous, intraarterial, intraosseous, intramuscular, intradermal, subcutaneous, intranasal and intraperitoneal routes. Components administered systemically may be modified or formulated to target the components to the eye.

Local modes of administration include, by way of example, intraocular, intraorbital, subconjuctival, intravitreal, subretinal or transscleral routes. In an embodiment, significantly smaller amounts of the components (compared with systemic approaches) may exert an effect when administered locally (for example, intravitreally) compared to when administered systemically (for example, intravenously). Local modes of administration can reduce or eliminate the incidence of potentially toxic side effects that may occur when therapeutically effective amounts of a component are administered systemically.

In an embodiment, components described herein are delivered by subretinally, e.g., by subretinal injection. Subretinal injections may be made directly into the macular, e.g., submacular injection.

In an embodiment, components described herein are delivered by intravitreal injection. Intravitreal injection has a relatively low risk of retinal detachment risk. In an embodiment, nanoparticle or viral, e.g., AAV vector, e.g., an AAV5 vector, e.g., a modified AAV5 vector, an AAV2 vector, e.g., a modified AAV2 vector, is delivered intravitreally.

Methods for administration of agents to the eye are known in the medical arts and can be used to administer components described herein. Exemplary methods include intraocular injection (e.g., retrobulbar, subretinal, submacular, intravitreal and intrachoridal), iontophoresis, eye drops, and intraocular implantation (e.g., intravitreal, sub-Tenons and sub conjunctival).

Administration may be provided as a periodic bolus (for example, subretinally, intravenously or intravitreally) or as continuous infusion from an internal reservoir (for example, from an implant disposed at an intra- or extra-ocular location (see, U.S. Pat. Nos. 5,443,505 and 5,766,242)) or from an external reservoir (for example, from an intravenous bag). Components may be administered locally, for example, by continuous release from a sustained release drug delivery device immobilized to an inner wall of the eye or via targeted transscleral controlled release into the choroid (see, for example, PCT/USOO/00207, PCT/US02/14279, Ambati 2000a, and Ambati 2000b. A variety of devices suitable for administering components locally to the inside of the eye are known in the art. See, for example, U.S. Pat. Nos. 6,251,090, 6,299,895, 6,416,777, 6,413,540, and PCT/USOO/28187.

In addition, components may be formulated to permit release over a prolonged period of time. A release system can include a matrix of a biodegradable material or a material which releases the incorporated components by diffusion. The components can be homogeneously or heterogeneously distributed within the release system. A variety of release systems may be useful. However, the choice of the appropriate system will depend upon rate of release required by a particular application. Both non-degradable and degradable release systems can be used. Suitable release systems include polymers and polymeric matrices, non-poly meric matrices, or inorganic and organic excipients and diluents such as, but not limited to, calcium carbonate and sugar (for example, trehalose). Release systems may be natural or synthetic. However, synthetic release systems are preferred because generally they are more reliable, more reproducible and produce more defined release profiles. The release system material can be selected so that components having different molecular weights are released by diffusion through or degradation of the material.

Representative synthetic, biodegradable polymers include, for example: polyamides such as poly(amino acids) and poly (peptides); polyesters such as poly(lactic acid), poly(glycolic acid), poly(lactic-co-glycolic acid), and poly(caprolactone); poly (anhydrides); poly orthoesters; polycarbonates; and chemical derivatives thereof (substitutions, additions of chemical groups, for example, alkyl, alkylene, hydroxylations, oxidations, and other modifications routinely made by those skilled in the art), copolymers and mixtures thereof. Representative synthetic, non-degradable polymers include, for example: polyethers such as poly(ethylene oxide), poly(ethylene glycol), and poly(tetramethylene oxide); vinyl polymers- polyacrylates and polymethacrylates such as methyl, ethyl, other alkyl, hydroxyethyl methacrylate, acrylic and methacrylic acids, and others such as poly(vinyl alcohol), poly(vinyl pyrolidone), and poly (vinyl acetate); poly (urethanes); cellulose and its derivatives such as alkyl, hydroxyalkyl, ethers, esters, nitrocellulose, and various cellulose acetates; polysiloxanes; and any chemical derivatives thereof (substitutions, additions of chemical groups, for example, alkyl, alkylene, hydroxylations, oxidations, and other modifications routinely made by those skilled in the art), copolymers and mixtures thereof.

Poly(lactide-co-glycolide) microsphere can also be used for intraocular injection. Typically the microspheres are composed of a polymer of lactic acid and glycolic acid, which are structured to form hollow spheres. The spheres can be approximately 15-30 microns in diameter and can be loaded with components described herein.

Bi-Modal or Differential Delivery of Components

Separate delivery of the components of an RNA-guided nuclease system, e.g., the RNA-guided nuclease molecule component (e.g., Cas9 or Cpfl molecule component), the gRNA molecule component, and the RHO cDNA molecule component, and more particularly, delivery of the components by differing modes, can enhance performance, e.g., by improving tissue specificity and safety.

In an embodiment, the RNA-guided nuclease molecule component, the gRNA molecule component, and the RHO cDNA molecule component, are delivered by different modes, or as sometimes referred to herein as differential modes. Different or differential modes, as used herein, refer modes of delivery that confer different pharmacodynamic or pharmacokinetic properties on the subject component molecule, e.g., n RNA-guided nuclease molecule, gRNA molecule, or RHO cDNA molecule. For example, the modes of delivery can result in different tissue distribution, different half-life, or different temporal distribution, e.g., in a selected compartment, tissue, or organ.

Some modes of delivery, e.g., delivery by a nucleic acid vector that persists in a cell, or in progeny of a cell, e.g., by autonomous replication or insertion into cellular nucleic acid, result in more persistent expression of and presence of a component. Examples include viral, e.g., adeno- associated virus or lentivirus, delivery.

By way of example, the components, e.g., an RNA-guided nuclease molecule, a gRNA molecule, and a RHO cDNA molecule can be delivered by modes that differ in terms of resulting half-life or persistent of the delivered component the body, or in a particular compartment, tissue or organ. In an embodiment, a gRNA molecule can be delivered by such modes. The RNA-guided nuclease molecule component can be delivered by a mode which results in less persistence or less exposure to the body or a particular compartment or tissue or organ. The RHO cDNA molecule component may be delivered by a mode that difference from that mode of the gRNA molecule component and the RNA-guided nuclease molecule component.

More generally, in an embodiment, a first mode of delivery is used to deliver a first component and a second mode of delivery is used to deliver a second component. The first mode of delivery confers a first pharmacodynamic or pharmacokinetic property. The first pharmacodynamic property can be, e.g., distribution, persistence, or exposure, of the component, or of a nucleic acid that encodes the component, in the body, a compartment, tissue or organ. The second mode of delivery confers a second pharmacodynamic or pharmacokinetic property. The second pharmacodynamic property can be, e.g., distribution, persistence, or exposure, of the component, or of a nucleic acid that encodes the component, in the body, a compartment, tissue or organ.

In an embodiment, the first pharmacodynamic or pharmacokinetic property, e.g., distribution, persistence or exposure, is more limited than the second pharmacodynamic or pharmacokinetic property.

In an embodiment, the first mode of delivery is selected to optimize, e.g., minimize, a pharmacodynamic or pharmacokinetic property, e.g., distribution, persistence or exposure.

In an embodiment, the second mode of delivery is selected to optimize, e.g., maximize, a pharmacodynamic or pharmcokinetic property, e.g., distribution, persistence or exposure.

In an embodiment, the first mode of delivery comprises the use of a relatively persistent element, e.g., a nucleic acid, e.g., a plasmid or viral vector, e.g., an AAV or lentivirus. As such vectors are relatively persistent product transcribed from them would be relatively persistent.

In an embodiment, the second mode of delivery comprises a relatively transient element, e.g., an RNA or protein.

In an embodiment, the first component comprises gRNA, and the delivery mode is relatively persistent, e.g., the gRNA is transcribed from a plasmid or viral vector, e.g., an AAV or lentivirus. Transcription of these genes would be of little physiological consequence because the genes do not encode for a protein product, and the gRNAs are incapable of acting in isolation. The second component, an RNA-guided nuclease molecule, is delivered in a transient manner, for example as mRNA or as protein, ensuring that the full RNA-guided nuclease molecule/gRNA molecule complex is only present and active for a short period of time.

Furthermore, the components can be delivered in different molecular form or with different delivery vectors that complement one another to enhance safety and tissue specificity.

Use of differential delivery modes can enhance performance, safety and efficacy.

E.g., the likelihood of an eventual off-target modification can be reduced. Delivery of immunogenic components, e.g., RNA-guided nuclease molecules, by less persistent modes can reduce immunogenicity, as peptides from the bacterially-derived Cas enzyme are displayed on the surface of the cell by MHC molecules. A two-part delivery system can alleviate these drawbacks.

Differential delivery modes can be used to deliver components to different, but overlapping target regions. The formation active complex is minimized outside the overlap of the target regions. Thus, in an embodiment, a first component, e.g., a gRNA molecule is delivered by a first delivery mode that results in a first spatial, e.g., tissue, distribution. A second component, e.g., an RNA-guided nuclease molecule is delivered by a second delivery mode that results in a second spatial, e.g., tissue, distribution. In an embodiment, the first mode comprises a first element selected from a liposome, nanoparticle, e.g., polymeric nanoparticle, and a nucleic acid, e.g., viral vector. The second mode comprises a second element selected from the group. In an embodiment, the first mode of delivery comprises a first targeting element, e.g., a cell specific receptor or an antibody, and the second mode of delivery does not include that element. In embodiment, the second mode of delivery comprises a second targeting element, e.g., a second cell specific receptor or second antibody. When the RNA-guided nuclease molecule is delivered in a vims delivery vector, a liposome, or polymeric nanoparticle, there is the potential for delivery to and therapeutic activity in multiple tissues, when it may be desirable to only target a single tissue. A two-part delivery system can resolve this challenge and enhance tissue specificity. If the gRNA molecule and the RNA-guided nuclease molecule are packaged in separated delivery vehicles with distinct but overlapping tissue tropism, the fully functional complex is only formed in the tissue that is targeted by both vectors.

Ex vivo delivery

In some embodiments, components described in Table 8 are introduced into cells which are then introduced into the subject. Methods of introducing the components can include, e.g., any of the delivery methods described in Table 9.

VIII. Modified Nucleosides, Nucleotides, and Nucleic Acids

In some embodiments of the present disclosure, modified nucleosides and/or modified nucleotides can be present in nucleic acids, e.g., in a gRNA molecule provided herein. Some exemplary nucleoside, nucleotide, and nucleic acid modifications useful in the context of the present RNA-guided nuclease technology are provided herein, and the skilled artisan will be able to ascertain additional suitable modifications that can be used in conjunction with the nucleosides, nucleotides, and nucleic acids and treatment modalities disclosed herein based on the present disclosure. Suitable nucleoside, nucleotide, and nucleic acid modifications include, without limitation, those described in U.S. Patent Application No. US 2017/0073674 A1 and International Publication No. WO 2017/165862 Al, the entire contents of each of which are incorporated by reference herein.

IX. Methods of Assays

Uni-Directional Targeted Sequencing (UDiTaS)

The UDiTaS method used for analyzing gene editing was performed as set forth in Giannoukos 2018 and Internationa] Publication No. WO 2018/129368, the entire contents of each of which are incorporated by reference herein.

Reverse-transcription quantitative PCR (RT-qPCR)

The RT-qPCR for analysis of eoRHO, hRHO, gRNA, and SaCas9 mRNA levels was performed as follows. RNA was extracted from the tissues/cells using All-Prep DNA/RNA Kits (Qiagen). The total RNA amount was quantified using the Quanti-iT RNA Kit (Thermo Fisher Scientific). 20 ng of RNA was first primed for 10 minutes at 25 °C, then reverse- transcribed using SuperScript IV VILO Master Mix (Thermo Fisher Scientific) for 15 minutes at 65°C, and then the reverse-transcriptase was inactivated for 5 minutes at 85 °C. The subsequent cDNA was stored at −20 °C. For the qPCR, reaction mixtures (10 µl) contained 5 µl of 2X TaqMan Multiplex Master Mix (Thermo Fisher Scientific), 0.25 µL of the 40X primer-probe TaqMan Mix (Thermo Fisher Scientific), and 2 µl of the cDNA. After an initial denaturation cycle (95 °C for 3 minutes), the product was amplified in 40 PCR cycles (95 °C for 15 seconds, 60 °C for 60 seconds) followed by a melting curve analysis using the Bio-Rad CFX384 Real Time Thermocycler. RT-qPCR primers are set forth in Table 31. The quantification cycles (Cq) were analyzed for each gene and gene expression levels were presented as numbers of molecules per µg of RNA based on the standard curves. The data were analyzed with Microsoft Excel and GraphPad Prism. Table 31: RT-qPCR Primers Target Description 5'→3' sequence Codon Forward Primer GCGTGGCCTTCTACATCTTT (SEQ ID NO:1020) The NanoString nCounter Element assay for analysis of coRHO, and hRHO mRNA levels was performed as follows. The NanoString technology is based on single-molecule imaging of color-coded barcodes bound to target-specific probes. The NanoString nCounter Elements assay provides direct digital quantification of up to 216 targets per sample without bias from first strand synthesis or PCR amplification. Fluorescently barcoded specific Reporter Tags and universal biotinylated Capture Tags hybridize to target-specific oligonucleotide probes for each mRNA of interest for up to 96 samples in one plate. In each reaction, positive and negative NanoString controls are included to assess efficiency, linearity, and the limit of detection. After hybridization, purification and immobilization of the complexes are performed by the nCounter Prep Station, a liquid handling robot. The sample cartridge is transferred to the Digital Analyzer, a fully automated imaging and data collection device, where the expression level of a gene is measured by imaging and counting each sample’s fluorescent color barcodes. Gene expression analysis is sensitive down to a 0.1–0.5 fM with replicates averaging R2 of 0.999 over a 3-log dynamic range. The Nanostring probe binding sites used for analysis of coRHO, and hRHO mRNA are set forth in Table 32. Table 32: List of Nanostring probe binding sites for the NHP and mouse studies Gene of Interest P ^{osition Target Seq} HUGO ( _GOI) ^uence _Gene ^Species 145 156624540.2 Liquid chromatography-mass spectrometry (LC-MS)

The LC-MS assay for analysis of RHO protein levels was performed as follows. Frozen retinal punches were pulverized (SPEX Sample Prep Geno/Grinder 2189), followed by homogenization in phosphate buffered saline (Tissue Lyser II, Qiagen 85300). Total protein was extracted from homogenate in AlphaLISA lysis buffer (Perkin Elmer AL003C10) supplemented with HALT protease inhibitor cocktail (Thermo 87785), benzonase nuclease (Sigma Aldrich E1014) and MgC12 (Thermo AM9530G). The total protein was quantified using Pierce BCA protein assay (Thermo 23225). The equivalent of 22 ug of total protein per sample was buffer exchanged into 8M urea / 100 mM ammonium bicarbonate / 10 mM methionine buffer over 10.5 kDa 0.5 mL MWCO Amicon filter coated with 0.1% bovine serum albumin. Protein was denatured with DTT, alkylated with iodoacetamide, and digested stepwise with Trypsin at 8M urea and Lys-C at <1M urea. Reaction was quenched with trifluoroacetic acid and supplemented with internal standards.

Two species of specific peptides for human (SAAIYNPVIYIMMNK (SEQ ID NO: 1042)) and non-human primate (SASIYNPVIYIMMNK (SEQ ID NO: 1043)) and the equivalent heavy labeled synthetic internal standards were separated and monitored using liquid chromatography tandem mass spectrometry (LC-MS/MS). Samples were separated on Waters XBridge peptide BEH C18 column (2.5 pm x 2.1 pm x 100 mm, 300 A) at 40°C and 0.4 ml/min flow rate across stepwise gradient of mobile phase A: 0.1% formic acid and B: 0.1% formic acid in acetonitrile. The LC (Shimadzu LC-30AD) was coupled to Sciex API 6500+ TQ mass spectrometer in positive mode and two transitions per peptide were selectively quantified by multiple reaction monitoring (MRM) method. Peptides were normalized to the volume digested per sample and quantified against a standard curve as the peak area ratio of analyte (human and NHP peptide) to the equivalent internal standard (heavy labeled synthetic peptide).

Examples

The following Examples are merely illustrative and are not intended to limit the scope or content of the disclosure in any way.

Example 1 : Screening of gRNAs for editing RHO alleles in T cells

Approximately 430 gRNAs targeting various positions within the RHO gene for use with SaCas9 were designed and screened for editing activity in T cells. Briefly, SA Cas9 and guide RNA were complexed at a 1:2 ratio (RNP complex) and delivered to T cells via electroporation. Three days after electroporation, gDNA was extracted from T cells and the target site was PCR amplified from the gDNA. Sequencing analysis of the RHO PCR gene product was evaluated by next generation sequencing (NGS). Table 18 below provides the RNA and DNA sequences of the targeting domains of the gRNAs that exhibited > 0.1% editing in T cells. These data indicate that gRNA comprising targeting domains set forth in Table 18 and Cas9 support editing of the RHO gene.

Example 2: Dose-dependent editing of RHO alleles in HEK293 cells

Three gRNAs whose target sites are predicted to be within exon 1 or exon 2 of the RHO gene, RHO-3, RHO-7, and RHO-10 (Table 17), were selected for further optimization and testing for dose-dependent editing with Cas9. Briefly, increasing concentrations of control plasmid (expressing SaCas9 with scrambled gRNA that does not target a sequence within the human genome) or plasmids expressing Cas9 and gRNA were delivered to HEK293 cells by electroporation. Three days after electroporation, gDNA was extracted from HEK293 cells and the gRNA target site was PCR amplified from the gDNA. Sequencing analysis of the RHO PCR gene product was evaluated by NGS. The increasing concentration of Cas9/gRNA plasmid supported an increase in indels at the RHO gene to 80% for each of the gRNAs tested (Fig. 4). Sequencing analysis indicated that increasing the plasmid concentration resulted in an increase in indels.

Table 17: gRNAs Targeting RHO Gene

Specificity of the gRNA (/. _<? ., RHO-3, RHO-7, RHO-10) and Cas9 ribonucleoprotein complexes was evaluated using two different assays that are well-known to skilled artisans for profiling CRISPR-Cas9 specificity, the Digenome-seq (digested genome sequencing) and GUIDE-seq assays. No apparent off target editing was detected under physiological conditions for RNP comprising RHO-3, RHO-7, or RHO-10 gRNA complexed with Cas9 (data not shown).

The efficiency of knocking down protein expression was evaluated using a RHO- mCherry line (Fig. 19A). Briefly, the HEK293T cell line expressing a fusion protein of RHO-mCherry driven by a CMV promoter was transfected with plasmids expressing SaCas9 and gRNA at 13 doses in triplicate to generate a dose-response curve. The amount of mean fluorescence intensity (MFI) of mCherry was determined using flow cytometry and analyzed as a percentage of pUC19 control. Results demonstrated a dose-dependent knockdown of RHO-mCherry by RNP containing RHO-3, RHO-7, or RHO-10 gRNAs (Fig. 19B).

Example 3 : Characterization of novel RHO alleles generated by simulation of on-targeted editing by RHO-3. RHO-7. and RHO-10 gRNAs

The cut sites generated by on-targeted editing of RHO-3, RHO-7, or RHO-10 gRNA (see targeting domains in Table 17) of RHO alleles were predicted. Fig. 5 illustrates the predicted cutting locations of RHO-3, RHO-7, or RHO-10 gRNAs on the RHO human cDNA and resulting lengths of RHO protein. RHO-3 is predicted to target Exon 1, RHO-10 is predicted to target the boundary of Exon 2 and Intron 2, and RHO-7 is predicted to target the boundary of Exon 1 and Intron 1 of RHO cDNA. Deletions of 1 or 2 base pairs at the RHO- 3, RHO-10, or RHO-7 target sites are predicted to cause frameshifts in the RHO cDNA resulting in abnormal RHO proteins. Fig. 6 shows schematics of the predicted RHO alleles resulting from editing by RHO-3, RHO-10, or RHO-7 gRNAs.

The effects of the alleles generated by on- targeted editing by RHO-3, RHO-7, or RHO-10 gRNA were characterized to determine whether editing using these gRNAs could result in potentially deleterious RHO alleles. Briefly, wild-type (WT) or mock-edited RHO alleles were cloned into mammalian expression plasmids under the control of a CMV promoter and lipofected into HEK293 cells. Mock-edited RHO alleles included each of the mutated alleles shown in Fig. 6 (i.e., RHO-3 (-1, -2, or -3 bp), RHO-10 (-1, -2, or -3 bp), or RHO-7 (-1 bp, -2 bp, -3 bp)). The well-known P23H RHO variant leading to a dominant form of retinitis pigmentosa was also cloned and tested. After 48 hours of overexpression, cell viability for WT and each mock-edited allele was assessed using ATPLite Luminescence Assay (Perkin Elmer).

While WT RHO overexpression induced relatively no cytotoxicity with respect to the vector control (pUC19 plasmid, upper dotted line), P23H RHO resulted in 50% cell death (lower dotted line), as expected (Fig. 7A). Furthermore, expression of the frameshifting of one- or two-base pair deletions at the RHO-3, RHO-7, or RHO-10 gRNA target sites did not induce significant loss in cell viability with respect to WT RHO (Fig. 7A, see RHO-3 1 and 2 bp del; RHO-10 1 and 2 bp del; and RHO-7 1 and 2 bp del). However, for in-frame three- base pair deletions at RHO-3 and RHO-10 target sites, there was a significant loss in cell viability, resulting in levels of cell death comparable to that of P23H RHO (Fig. 7A, see RHO-3 3 bp del and RHO-103 bp del). This was not the case for all gRNAs as a three-base pair deletion at the RHO-7 sequence resulted in a non-cytotoxic RHO allele (Fig. 7A, see RHO-7 3bp del).

Next, to determine whether the RHO-3, RHO-7, and RHO-10 mock-edited RHO alleles could reduce toxicity of the P23H variant of RHO, mock-edited RHO-3, RHO-7, and RHO-10 RHO alleles shown in Fig. 6 and containing the P23H mutation were cloned into mammalian expression plasmids under the control of a CMV promoter and lipofected into HEK293 cells. After 48 hours of overexpression, cell viability for WT and each mock-edited allele was assessed using ATPLite Luminescence Assay (Perkin Elmer).

Expression of the frameshifting of one- or two-base pair deletions at the RHO-3, RHO-7, or RHO-10 gRNA target sites reduced toxicity of the P23H variant of RHO and did not induce significant loss in cell viability with respect to WT RHO (Fig. 7B, see RHO-3 1 and 2 bp del, RHO-10 1 and 2 bp del and RHO-7 1 and 2 bp del). The in-frame three-base pair deletions at RHO-3 and RHO-10 target sites did not reduce toxicity of the P23H variant of RHO as there was a significant loss in cell viability, resulting in levels of cell death comparable to that of P23H RHO (Fig. 7B, see RHO-3 3 bp del and RHO-103 bp del). However, the three-base pair deletion at the RHO-7 target sequence reduced toxicity of the P23H variant of RHO and resulted in a non-cytotoxic RHO allele (Fig. 7B, see RHO-7 3bp del).

These data indicate that out-of-frame RHO edits produced by RHO-3, RHO-7, or RHO-10 gRNA were productive and non- toxic while the effect of in- frame edits were gRNA/locus dependent.

Example 4: Editing of non-human primate explants by ribonucleoproteins comprising Cas9 and gRNA targeting the RHO gene

The ability of ribonucleoproteins comprising RHO-9 gRNA targeting the RHO gene and SaCas9 to edit explants from non-human primates (NHP) was assessed. The RHO-9 gRNA (comprising the targeting domain sequence set forth in SEQ ID NO: 108 (RNA) (SEQ ID NO:608 (DNA), Table 1) is cross-reactive and can edit both human and NHP RHO sequences.

Briefly, retinal explants from NHP donors were harvested and transferred to a membrane on a trans-well chamber in a 24 well plate. 300 pi of retinal media was added to the 24 well plate (i.e., Neurobasal-A media (no phenol red) (470 mL) containing B27 (with VitA) 50X (20 mL), Antibiotic- Antimycotic (5 mL), and GlutaMAX 1% (5 mL)). Transduction with dual AAV comprising RHO-9 gRNA, SaCas9, and Replacement RHO occurred after 24-48 hours. AAVs were diluted to the desired titer (10 ¹² vg/ml)) with the retinal media to obtain the final concentration in a total of 100 mΐ. The diluted/titered AAV was added dropwise on top of the explant in the 24 well plate. 300 mΐ of retinal media was replenished every 72 hours. After 2-4 weeks, explants were lysed to obtain DNA, RNA and protein for molecular biology analysis. To measure the percentage of rods in the explants, a rod-specific mRNA (neural retina leucine zipper (NRL)) was extracted from the explants and measured. The housekeeping RNA (beta actin (ACTB)) was also measured to determine the total number of cells.

As shown in Fig. 8, each data point represents a single explant, which can contain differing numbers of rod photoreceptors. The x-axis shows the delta between ACTB and NRL RNA levels as measured by RT-qPCR, which is a measure for the percentage of rods in the explant at the time of lysing the explants. A correlation between significant editing and high percentage of rods was shown, demonstrating that robust editing levels can be achieved in explants with a substantial number of rods (Fig. 8). These data show that AAV expression of RNPs containing SaCas9 and a gRNA targeting RHO can efficiently edit non-human primate explants.

Example 5: Optimization of RHO replacement vector

Vector systems were developed with the objective of knocking down the levels of endogenous RHO (e.g., a defective mutant RHO protein) in a cell and replacing that endogenous RHO with exogenously provided functional RHO expressed from a RHO replacement vector. Various components of the RHO replacement vector (e.g., promoter, UTRs, RHO sequence) were optimized to identify an optimal RHO replacement vector for maximal expression of RHO mRNA and RHO protein. First, a dual luciferase system was designed to test the impact that different lengths of the RHO promoter have on RHO expression. The components of the luciferase system included a Renilla luciferase driven by CMV in the backbone to normalize for plasmid concentrations and transfection efficiencies

(Fig. 9).

Briefly, plasmids containing different lengths of the RHO promoter and the RHO gene tagged with a firefly luciferase separated by a self-cleaving T2A peptide (100 ng/10,000 cells) were transfected into HEK293 cells along with a plasmid expressing NRL, CRX, and NONo (100 ng/10,000) to turn on expression from the RHO promoters (see Yadav 2014, the entire contents of which are incorporated herein by reference). 72 hours later the cells were lysed and both transfection efficiency (Firefly) and experimental variable (NanoLuc) were analyzed. The Nano-Glo® Dual-Luciferase® Reporter Assay System (Promega Corporation, Cat# N1521) was used to measure luminescence. Luminescence from both Firefly and NanoLuc were measured. As shown in Fig. 10, promoters of different lengths were shown to be functional, including the minimal 250 bp RHO promoter (SEQ ID NO:44).

Next, varying 3’ UTRs were tested to determine whether 3’ UTRs can improve expression of RHO mRNA and RHO protein. Briefly, 3’ UTRs from highly stable transcripts and genes were cloned downstream of CMV RHO (i.e., HBA1 3’ UTR (SEQ ID NO:38), short HBA1 3’ UTR (SEQ ID NO:39), TH 3’ UTR (SEQ ID NO:40), COL1A1 3’UTR (SEQ ID NO:41), ALOX15 3’UTR (SEQ ID NO:42), and minUTR (SEQ ID NO:56)). Vectors (500 ng) were transfected into HEK293 cells (80,000 cells/well). 72 hours later the cells were lysed, and RHO mRNA and protein expression levels were determined using RHO RT- qPCR and RHO ELISA assays, respectively. Fig. 11A shows that incorporation of 3’ UTRs from stable transcripts into the RHO replacement vector improved RHO mRNA expression levels. Fig. 11B shows that incorporation of 3’ UTRs from stable transcripts into the RHO replacement vector also improved RHO protein expression levels.

Next, incorporation of sequences of RHO introns 1, 2, 3, or 4 were added to RHO cDNA (i.e., SEQ ID NOs:4-7, respectively) in the RHO replacement vector to determine the impact on RHO protein expression. Vectors (500 and 250 ng) were transfected into HEK293 cells (80,000/well). 72 hours later the cells were lysed, and RHO protein expression was determined using RHO ELISA. Fig. 12 shows that addition of introns affects RHO protein expression.

Lastly, different codon optimized RHO cDNA constructs (i.e., SEQ ID NOs:13-18) were tested to determine the impact of codon optimization on RHO expression. Vectors (500 and 250 ng) were transfected into HEK293 cells (80,000/well). 72 hours later the cells were lysed and RHO protein expression was determined using a RHO ELISA. Fig. 13 shows that codon optimization of the RHO cDNA can impact RHO protein expression. Example 6: In vivo editing using self-limiting Cas9 vector system to reduce Cas9 levels after successful editing

The ability of a dual vector system expressing Cas9 and gRNAs to edit the RHO genome and to render Cas9 vector expression non-functional was tested in vivo. The self- limiting vector system has previously been published (see WO2018/106693, published on June 14, 2018, and entitled Systems and Methods for One-Shot guide RNA (ogRNA) Targeting of Endogenous and Source DNA, the entire contents of which are incorporated herein by reference). Briefly, a Cas9 vector system was generated in which the Cas9 vector comprised a target site for the RHO gRNA within the Cas9 cDNA (SD Cas9). Six weeks after administration of the SD Cas9 and RHO vectors, Cas9 protein levels, Cas9 AAV, and editing of RHO was assessed.

Fig. 14A indicates that the SD Cas9 vector system demonstrated successful silencing of Cas9 levels. Fig. 14B indicates that the vector system carrying the SD Cas9 system resulted in robust editing at the RHO locus, albeit at slightly lower levels as compared to a vector system encoding a wild-type Cas9 sequence.

Example 7 : Editing of human explants by ribonucleoproteins comprising gRNA targeting the RHO gene and Cas9

The ability of ribonucleoproteins comprising RHO-9 gRNA (Table 1) targeting the RHO gene and Cas9 to edit human explants was assessed. Briefly, retinal explants from one human donor were harvested and transferred to a membrane on a trans-well chamber in a 24 well plate. 300 pi of retinal media was added to the 24 well plate (i.e., Neurobasal-A media (no phenol red) (470 mL) containing B27 (with VitA) 50X (20 mL), Antibiotic- Antimycotic (5 mL), and GlutaMAX 1% (5 mL)). Different “knock-down and replace” strategies were compared: “shRNA”: transduction of retinal explants with shRNA targeting the RHO gene and a replacement vector providing a RHO cDNA (as published in Cideciyan 2018); “Vector A”: a two-vector system (Vector 1 comprising SaCas9 driven by the minimal RHO promoter (250 bp), and Vector 2 comprising a codon-optimized RHO cDNA (Codon 6 (SEQ ID NO: 18)) and comprising a HBA1 3’ UTR under the control of the minimal 250 bp RHO promoter, as well as a the RHO-9 gRNA under the control of a U6 promoter); “Vector B”: a two- vector system identical to “Vector A” except for Vector 2 comprising a wt RHO cDNA; and “UTC”: untransduced control. The respective AAVs were diluted to the desired titer (1 x 10 ¹² vg/ml) with the retinal media to obtain the final concentration in a total of 100 mΐ. The diluted/titered AAV was added dropwise on top of the explant in the 24 well plate. 300 pi of retinal media was replenished every 72 hours. After 4 weeks, explants were lysed to obtain protein for molecular biology analysis. The ratio of RHO protein: total protein was measured. Data indicate that Vector A (comprising Vector 2 with the minimal 250 bp promoter, RHO cDNA, HBA1 3’ UTR, and RHO-9 gRNA), resulted in robust expression of RHO protein (Fig. 15).

Example 8: Editing of human explants by ribonucleoproteins comprising gRNA targeting the RHO gene and Cas9

The ability of ribonucleoproteins comprising RHO-3 or RHO-7 gRNAs (Table 1) targeting the RHO gene and SaCas9 to edit human explants was assessed. Briefly, retinal explants from one human donor were harvested and transferred to a membrane on a trans well chamber in a 24 well plate. 300 mΐ of retinal media was added to the 24 well plate (i.e., Neurobasal-A media (no phenol red) (470 mL) containing B27 (with VitA) 50X (20 mL), Antibiotic- Antimycotic (5 mL), and GlutaMAX 1% (5 mL)). Dual AAV vector systems comprising Vector 1 (encoding SaCas9 under the control of the minimal 625 bp RHO promoter) and Vector 2 (encoding RHO-3 or RHO-7 gRNA under the control of a U6 promoter and exogenous RHO under the control of the minimal 250 bp RHO promoter) were diluted to the desired titer (1 x 10 ¹² vg/ml) with the retinal media to obtain the final concentration in a total of 100 mΐ. Vector 1 comprises the sequence set forth in SEQ ID NO: 1009. Vector 2 containing the RHO-7 gRNA is shown in Fig. 16 (SEQ ID NO: 11). Vector 2 containing the RHO-3 gRNA is the same as the sequence shown in Fig. 16 except that the sequence of RHO-7 was changed to the sequence of RHO-3 (Table 1) (SEQ ID NO: 1010). The expression of Cas9 and gRNA from different vectors ensured that cells would only be edited in the presence of replacement RHO expression. The diluted/titered AAV was added dropwise on top of the explant in the 24 well plate. 300 mΐ of retinal media was replenished every 72 hours. After 4 weeks, explants were lysed to obtain DNA for NGS analysis and indel profile was determined. Data indicate that the indels generated by RNP comprising the RHO-3 or RHO-7 gRNA are predominantly out-of-frame and productive RHO edits ex vivo for each of these guides (Fig. 20). A table with the frameshifting profile for RHO-3 and RHO-7 is provided in Fig. 20. Greater than 93% of editing events resulted in frameshift indels ex vivo, suggesting minimal risk of generating a dominant-negative RHO allele through in-frame editing. Example 9: Characterization of RHO expression vectors

Next, various vectors having different configurations of components were tested to determine optimal vector configurations for RHO expression. Briefly, HEK293 cells were transfected with different configurations of the replace vector as shown in Table 19 below in quadruplicate and RHO mRNA levels were assessed by RT-qPCR.

Table 19: Different Configurations Used for Replace Vector

Vector 7, which comprises the sequence set forth in SEQ ID NO: 11, expresses 8-fold over benchmark vector (Cideciyan 2018) and was identified as the ‘optimized’ replace vector (Fig. 21) and was cloned into an AAV to generate vims. The AAV was used to transduce human retinal explants with the “optimized” replace vector at increasing concentrations and RHO mRNA levels were assessed by using RT-qPCR. Results from these experiments demonstrate that RHO mRNA levels from the replace vector are dose dependent and approach endogenous RHO level (indicated by dotted line, > 25%, see Cideciyan 1998) at a concentration of lx 10 ¹¹ and higher (Fig. 22).

Table 20 below shows the different vector configurations that were tested to arrive at the ‘optimized’ replace vector. A schematic of the optimized replace vector is shown in Fig. 23, and an exemplary replace vector sequence encodes the RHO-7 gRNA and comprises the sequence set forth in SEQ ID NO: 11 (see Fig. 16). In certain embodiments, the RHO-7 gRNA sequence shown in Fig. 16 may be replaced with a different gRNA sequence. In certain embodiments, the RHO-7 gRNA sequence shown in Fig. 16 may be replaced with a RHO-3 gRNA sequence (Table 1) (SEQ ID NO: 1010). In certain embodiments, the replace vector may comprise the sequence set forth in SEQ ID NO: 1006. The components of the vector used in the ‘optimized’ replace vector (i.e., shown in Figs. 16 and 23) are shown in Table 20 with an asterisk (i.e., 2505’UTR, SV40 Intron, Kozak sequence (TCCGCCACC), Codon 6, and HBA1 Stable UTR). Introns were not incorporated into the final ‘optimized’ replace vector because they were incompatible with codon optimization. RHO 3’ UTR was not incorporated into the final vector because a 3’ stable UTR was chosen. Table 20: Different Configurations Used for Replace Vector

Example 10: Clinically relevant editing and high replacement RHO expression achieved by dual AAV system in a humanized mouse model

A humanized mRho ^hRHO/+ mouse model (Fig. 24) was utilized to evaluate the levels of editing that could be achieved using the dual AAV system encoding RHO-3 or RHO-7 gRNAs. Briefly, the dual AAV vector system (Fig. 23) with Vector 1 encoding SaCas9 under the control of the minimal 625 bp RHO promoter (Vector 1 comprises the sequence set forth in SEQ ID NO: 1005) and Vector 2 encoding either RHO-3 or RHO-7 gRNA under the control of a U6 promoter and exogenous codon-optimized RHO under the control of the minimal RHO 250 bp promoter was subretinally injected at a 1:1 ratio into the eye of mRho ^hRHO/+ mice. Vector 2 containing the RHO-7 gRNA comprises the sequence set forth in SEQ ID NO:11. Vector 2 containing the RHO-3 gRNA comprises the sequence set forth in SEQ ID NO:1006. Table 21 provides additional information about the study design for this experiment. Table 21: Study Design for Dual AAV System in mRho ^hRHO/+ Mice (1:1 Ratio) Sample Ratio Virus Treatment Dose Total Mice Time Concentration (n) Points The percentage of normalized productive editing was assessed using UDiTaS (Giannoukos 2018) at 6 weeks and 13 weeks post-injection. Briefly, the amount of productive editing in each mouse was measured with UDiTaS (Giannoukos 2018). Productive editing was calculated for genomic DNA extracted from the entire neural retina, where photoreceptors represent 85-90% of the neural retina cells with 97% of the total photoreceptors being rods (Jeon 1998). The fraction of the retina transduced by 1 μL subretinal dose was determined as described by Maeder 2019. Briefly, wild-type mice were dosed with AAV5-GRK-GFP or AAV5-minRHO-mCherry and the percentage of transduced neural retina was measured on fluorescent images of flat-mounted retina 4 weeks post- injections. Approximately 21.5% of the neural retina area was transduced following injection. This percentage was used to derive a normalization factor which was applied to calculate productive editing rates for the entire retina: • Transduction area of retina: 21.5% • Transduction multiplier: 100%/21.5% = 4.6 • Productive editing in mouse sample = Total editing events= small insertions/deletions (indels) + AAV insertions • Normalized productive editing in the rods = Productive editing in mouse sample x 4.6 As shown in Fig. 25, both the RHO-3 and RHO-7 gRNAs dual vector systems achieved therapeutically relevant levels of editing in vivo (> 25%, see Cideciyan 1998), which was consistent over time (at weeks 6 and 13). By contrast, injection of the vehicle only control did not result in editing at the week 6 and week 13 time points. The data corresponding to Fig. 25 are set forth in Table 22.

Table 22: Editing by RHO-3 and RH07 gRNAs in mRho ^hRHO/+ Mice

Indel size was also assessed using UDiTaS at 6 weeks and 13 weeks post-injection (Fig. 26, Table 23) (Giannoukos 2018). Results indicated that both the RHO-3 and RHO-7 gRNAs dual vector systems can produce small indels and partial AAV insertions that can cause frameshift of the coding sequence and permanently ablate the expression of the endogenous Rhodopsin. Both RHO-3 and RHO-7 produced < 10% in frame-indels, suggesting that in-frame editing was unlikely and did not lead to deleterious effects in vivo (Fig. 26, Table 23). Analysis of the indel profile indicated that the editing profile is different for the two gRNAs (Fig. 26). Additionally, the editing profile of each gRNA is consistent over time (Fig. 26).

Table 23: Indel profile for RHO-3 and RH07 gRNAs in mKho ^hRHO/+ Mice

Next, various ratios of Vector 1 encoding SaCas9 (Vector 1 comprises the sequence set forth in SEQ ID NO: 1005) and Vector 2 encoding RHO-3 gRNA (Vector 2 comprises the sequence SEQ ID NO: 1006) were tested using the humanized mouse model mRho ^hRHO/+ . Briefly, the dual AAV vector system (Fig. 23) was subretinally injected at Vector 1: Vector 2 ratios of 5:1, 1:1, 1:5, or 1:10 into the eye of mRho ^hRHO/+ mice. Table 24 provides additional information about the study design for this experiment. Table 24: Study Design for Dual AAV System in mRho ^hRHO/+ Mice (Various Ratios) Ratio Virus Treatment Total Concentration (vg/ml) Mice Time (n) point ) 5 Results indicated that AAV Vectors 1 and 2 at a 1:1 ratio led to therapeutically relevant editing levels (≥ 25%, see Cideciyan 1998) and significant increases in gRNA and Cas9 expression (Figs.27-29, Table 25). Normalized productive editing by UDiTaS (using the methods described above in Example 10) was greater than 25% for the Vector 1:Vector 2 10 ratios of 5:1 (30% editing), 1:1 (31% editing) and 1:5 (26% editing) at 6 weeks post-injection (Fig.27, Table 25). Significant differences of editing between vehicle and all four of the viral injection groups was demonstrated (Fig.27, Table 25). Lower Vector 1:Vector 2 ratios (1:5 and 1:10) resulted in lower product editing (Fig.27, Table 25). The editing results for the 5:1 and 1:1 ratios were very similar suggesting that reducing the amount of gRNA affects 15 editing less than reducing the amount of Cas9 at the 1:5 and 1:10 ratios (Fig.27, Table 25). Table 25: Normalized Productive Editing (%) for Dual Vector System (RHO-3 gRNA) Ratio Vehicle 5:1 1:1 1:5 1:10 Number of 12 22 21 22 22 The levels of RHO-3 gRNA and Cas9 mRNA were also determined for the varying vector ratios. The levels of RHO-3 gRNA and Cas9 mRNA were analyzed by RT-qPCR as described above in Section “IX. Methods of Assays”. Results indicated that injection of AAV Vector 1 and Vector 2 at a 1:1 ratio led to significant increases in gRNA and Cas9 expression (Figs. 28, 29, respectively). The gRNA and Cas9 mRNA levels strongly correlated with editing at all vector ratios (Figs. 27-29). Next, the expression of endogenous and exogenous RHO was assessed after injection of the Vector 1 and Vector 2 at the various ratios by measuring mRNA. Briefly, the expression of endogenous and exogenous RHO mRNA was analyzed by RT-qPCR as described above in Section “IX. Methods of Assays”. Endogenous RHO mRNA expression was reduced the greatest extent when AAV Vectors 1 and 2 were injected at the 1:1 ratio (Fig. 30). At this ratio, endogenous RHO mRNA expression was reduced by 33% relative to the vehicle control. Endogenous RHO mRNA expression was reduced by 30%, 28% and 29% relative to the vehicle control for the 5:1, 1:5 and 1:10 Vector 1: Vector 2 ratios, respectively. Moreover, the replacement codon-optimized RHO mRNA expression increased with increasing dose of Vector 2 (Fig. 31). These results indicate that at a 1:1 ratio, the dual AAV system demonstrated clinically relevant levels of editing, significantly increased gRNA and Cas9 mRNA levels, resulted in the highest level of endogenous RHO knockdown, and demonstrated >200-fold higher levels of replacement RHO mRNA expression compared with the vehicle control.

Example 11: Dose escalation and time course studies of the dual AAV system in a humanized mouse model

A humanized mRho ^hRHO/+ mouse model (Fig. 24) was utilized to evaluate the dose range to achieve clinically relevant levels of editing with the dual vector system encoding RHO-3 gRNA. Briefly, 1 pi of the dual AAV vector system (Fig. 23) with Vector 1 encoding SaCas9 under the control of the minimal 625 bp RHO promoter (Vector 1 comprises the sequence set forth in SEQ ID NO: 1005) and Vector 2 encoding RHO-3 gRNA under the control of a U6 promoter and exogenous codon-optimized RHO under the control of the minimal RHO 250 bp promoter (Vector 2 comprises the sequence set forth in SEQ ID NO: 1006) at a 1:1 ratio was injected subretinally into mRho ^hRHO/+ mice at the concentrations of lxlO ¹¹ , 3xl0 ⁿ , lxlO ¹² , 3xl0 ¹² , 6xl0 ¹² and 9xl0 ¹² vg/ml. Table 26 provides additional information about the study design for this experiment. Table 26: Design of Dose Escalation Study for the Dual AAV System in mRho ^hRHO/+ Mice

The percentage of normalized productive editing was assessed using UDiTaS at 6 weeks as described above in Example 10. As shown in Fig. 32 A, the editing levels increased with concentration and reached a plateau at the concentration of > 3xl0 ¹² vg/ml. The dual vector system achieved therapeutically relevant levels of editing in vivo (> 25%, see Cideciyan 1998) at concentrations of > 3xl0 ¹² . In the higher dosing groups (3xl0 ¹² , 6xl0 ¹² and 9xl0 ¹² vg/ml), over 70% of retinas showed levels of editing over 25% (Fig. 32B). By contrast, injection of the vehicle only control did not result in editing. The data corresponding to Fig. 32 are set forth in Table 27. Table 27: Normalized Productive Editing (%) of the Dual Vector System (RHO-3 gRNA) Injected at Different Concentrations in mRho ^hRHO/+ Mice Concentration 11 ( _vg/ml) ^{Vehicle 1x10} 3x10 ¹¹ 1x10 ¹² 3x10 ¹² 6x10 ¹² 9x10 ¹² determined at varying concentrations of the dual vector system. The methods used for analyzing the levels of mRNA are described above in Section “IX. Methods of Assays”. Results indicated that the expression levels of gRNA, Cas9 (measured by RT-qPCR) and RHO replacement (measured using the Nanostring nCounter gene expression assay) increased in a dose-dependent manner and reached a plateau at the concentration of 3x10 ¹² vg/ml (Fig. 33A and Fig.34) as observed for editing. The gRNA and Cas9 mRNA levels strongly correlated with editing in that higher expression levels correlated with higher editing levels before plateauing (Fig.33B). The endogenous RHO (hRHO) mRNA expression (measured using the Nanostring nCounter gene expression assay) was also significantly reduced in a dose-dependent manner between 1x10 ¹² - 6x10 ¹² vg/ml compared to the vehicle indicating that higher Cas9 and gRNA expression and higher editing levels generally correlated with lower endogenous RHO mRNA (Fig.35). Next, the pharmacokinetics of the dual AAV vector system was assessed in the humanized mRho ^hRHO/+ mice. Briefly, 1 µl of the dual AAV vector system (Fig.23), with Vector 1 encoding SaCas9 under the control of the minimal 625 bp RHO promoter (Vector 1 comprises the sequence set forth in SEQ ID NO:1005), and Vector 2 encoding RHO-3 gRNA (Table l) and a replacement exogenous RHO sequence (coRHO) (Vector 2 comprises the sequence set forth in SEQ ID NO:1006) at a ratio of 1:1 was injected subretinally into mRho ^hRHO/+ mice at concentrations of 1x10 ¹² , 3x10 ¹² , and 6x10 ¹² vg/ml. The levels of editing, and the mRNA levels of RHO-3 gRNA, Cas9 and coRHO were assessed at 1, 3, 6 and, 13 weeks post-injection. Table 28 provides additional information about the study design for this experiment. Table 28: Design of Time Course Study for the Dual AAV System in mRho ^hRHO/+ Mice (1:1 Ratio)

Results indicated that the percentage of normalized productive editing (measured by UDiTaS as described above in Example 10) increased over time at all concentrations and in a dose-dependent manner (Fig. 36). Editing levels reached a peak at 6 weeks at all concentrations and were stable for at least 13 weeks. Editing at 6 weeks was clinically relevant (> 25%, see Cideciyan 1998) at concentrations of 3xl0 ¹² and 6xl0 ¹² vg/ml. The data corresponding to Fig. 36 are set forth in Table 29. Similarly, RHO-3 gRNA, Cas9 mRNA (measured by RT-qPCR as described above in Section “IX. Methods of Assays”), and RHO replacement (measured by Nanostring nCounter gene expression assay, see Section IX. Methods of Assays above) mRNA levels increased over time at all concentrations and in a dose-dependent manner (Figs. 37A and 37B, Fig. 38), and reached a peak at 6 weeks at all concentrations and were stable for at least 13 weeks. The gRNA and Cas9 mRNA levels strongly correlated with editing levels (Fig. 37C). The endogenous RHO expression ( hRHO , measured by Nanostring nCounter gene expression assay as described above in Section “IX. Methods of Assays”) was significantly reduced at higher concentrations compared to the vehicle (Fig. 39). These results indicate that a concentration range of 3xl0 ¹² - 6xl0 ¹² vg/ml for the dual AAV system (at a 1:1 vector ratio) can achieve levels of editing > 25% and high levels of RHO replacement that are stable for at least 13 weeks in mice. Table 29: Normalized Productive Editing (%) of the Dual Vector System (RHO-3 gRNA) at 1, 3, 6 and 13 Weeks Post-Injection in mRho ^hRHO/+ Mice

Example 12: Efficacy study of the dual AAV vector system in non-human primates A non-human primate model (NHP) was utilized to evaluate the efficacy of the knock out and replace dual AAV vector system. Briefly, non-human primates were subretinally injected adjacent to the macula (Fig. 41) with one of the following:

(1) vehicle (PBS with 0.014% Tween 20),

(2) the knock-out and replace dual AAV vector system (Fig. 40) including Vector 1 encoding SaCas9 under the control of the minimal 625 bp RHO promoter (Vector 1 comprises the sequence set forth in SEQ ID NO: 1005) and Vector 2 encoding two RHO-3 gRNAs under the control of U6 promoters and exogenous RHO under the control of the minimal RHO 250 bp promoter (Vector 2 of the knock out and replace dual AAV vector system comprises the sequence set forth in SEQ ID NO: 1006), or (3) the knock-out only dual AAV vector system (Fig. 40) including Vector 1 encoding

SaCas9 under the control of the minimal 625 bp RHO promoter (Vector 1 comprises the sequence set forth in SEQ ID NO: 1005) and Vector 2 encoding two RHO-3 gRNAs and a staffer sequence (Vector 2 of the knock out only dual AAV vector system comprises the sequence set forth in SEQ ID NO: 1003). The stuffer sequence contains partially codon- optimized RHO cDNA and mCherry cDNA (SEQ ID NO: 1007).

Table 30 provides additional information about the study design for this experiment. Table 30: Design of Efficacy Study for the Dual AAV System in Non-human Primates

In the NHP study, neural retina tissue was collected for analysis from the AAV- transduced region only and thus normalization for transduced retinal area was not necessary. However, in addition to rod and cone photoreceptors, the retina contains several cell types. In contrast to mouse retina, a sizable proportion of primate retina (similar to humans) are composed of non-photoreceptor cells such as retinal ganglion cells, bipolar cells, and Miiller glia. Because SaCas9 is expressed only in rod photoreceptors, the fraction of retinal cells that are rod photoreceptor cells was estimated. Retinal histology sections across the transduced area were analyzed and it was determined that approximately 44% of the neural retinal cells are photoreceptors and, 95% of the total photoreceptors in the transduced area (superior- temporal quadrant adjacent of macula) are known to be rod photoreceptor cells (Packer 1989 and Wikler 1990).

Briefly, to determine the % of photoreceptors in the bleb area, 15 cross-sections (100- pm wide, at 20x magnification) from each animal of the vehicle-treated group covering the potential area were quantified by counting the nuclei numbers of the ganglion cell layer

(GCL), the inner nuclear layer (INL,) and the outer nuclear layer (ONL) (n=3 animals). The % of photoreceptors was calculated according to the following equation: Numbers of nuclei in ONL

Numbers of nuclei in GCL, INL and ONL = % of Photoreceptors 44% of photoreceptors among the neural retinal cells is an average from 3 animals. Therefore, productive editing in NHP samples was quantified as follows:

Percentage of rod photoreceptor cells within the transduced area:- 44%

Productive editing in NHP sample= Total editing events= small insertions/deletions (indels) + AAV insertions

Normalized productive editing in the rods = Productive editing in NHP sample x 2.3

The percentage of normalized productive editing was assessed using UDiTaS at 13 weeks post-injection. As shown in Fig. 42A, the knock out and replace dual AAV vector system demonstrated about 100% editing (i.e., therapeutically relevant levels of editing in vivo (> 25%, see Cideciyan 1998)) in the transduced photoreceptors at 13 weeks post injection with the concentrations of 3xl0 ¹² vg/ml and 6xl0 ¹² vg/ml. By contrast, injection of the vehicle only control did not result in editing. Editing in the knock out and replace group was higher than in the knock out only group suggesting better photoreceptor survival in the knock out and replace group due to the presence of the RHO replacement.

The levels of RHO-3 gRNA and Cas9 mRNA were also determined by RT-qPCR (as described above in Section “IX. Methods of Assays”). Results demonstrated expression of gRNA and Cas9 following injection in eyes treated with either dual AAV vector system (Fig. 42B). The gRNA and Cas9 mRNA levels strongly correlated with editing, i.e., higher expression levels correlated with higher editing (Fig. 42C). The endogenous NHP RHO mRNA levels, measured by Nanostring nCounter gene expression assay (see section IX. Methods of Assays above for method), were also significantly reduced at the concentrations of 3xl0 ¹² vg/ml and 6xl0 ¹² vg/mL of the treatment groups compared to the vehicle (Fig. 43A and 43B). Indeed, knockdown of the endogenous RHO mRNA resulted in almost 100% knockdown of the endogenous NHP RHO protein levels - approximately 0% of the endogenous RHO protein (measured by tandem mass spectrometry as described above in Section “IX. Methods of Assays”) was present at the concentration of 6x10 ¹² vg/mL and only about 10% was present at the concentration of 3xl0 ¹² vg/ml (Fig. 43B). Replacement RHO mRNA (measured by Nanostring nCounter gene expression assay, see section IX. Methods of Assays above for method) was significantly expressed relative to the vehicle and knock out dual AAV vector system controls at the concentrations of 3xl0 ¹² vg/ml and 6xl0 ¹² vg/mL, resulting in over 30% replacement RHO protein levels (measured by tandem mass spectrometry as described above in Section “IX. Methods of Assays”) at the concentration of 3xl0 ¹² vg/ml (Fig. 43C and 43D). A replacement of 30% rhodopsin protein was previously shown to be sufficient for maintaining visual function in a canine model. See Cideciyan 2018. In addition, in patients with RHO-associated autosomal dominant retinitis pigmentosa, areas of the retina with only 30 % normal rhodopsin levels show only minimal loss of rod sensitivity and no loss of cone sensitivity (Jacobson 1991). Thus, in certain embodiments, a replacement of 30% or more rhodopsin protein is a therapeutically effective amount of rhodopsin protein.

Next, the treated retinas of the non-human primates were assessed for RHO expression within the transduced area. The transduced region was identified by positive Cas9 genome staining by in situ hybridization (Fig. 44). Results showed successful AAV-Cas9 transduction in the treated groups, baseline endogenous RHO protein expression (measured by immunohistochemistry) was observed in the inner and outer segment (IS/OS) of photoreceptors in the vehicle group, RHO protein expression was almost absent in the knock out group while RHO protein expression was preserved in the knock out and replace group (Fig. 44). RHO protein expression appeared more pronounced in the lower concentration (3xl0 ¹² vg/ml) group (Fig. 44).

Histological analysis showed that retina morphology was improved in the knock out and replace treated group compared to the knock out only treated group at 13 weeks post injections (Fig. 45). A comparison of the knock out and replace and the knock out treated groups shows improved photoreceptor organization and improved IS/OS morphology. Morphological improvements appeared more pronounced in the knock out and replace lower concentration (3xl0 ¹² vg/ml) group (Fig. 45).

Finally, the retina function was assessed by performing full-field flash electroretinograms (ERGs) with Ganzfeld dome stimulus, with flash intensities according to ISCEV standard parameters and light adaptation time of 5 minutes (Retiport Gamma, Roland Consult). ERG a-wave and b-wave were significantly reduced in the knock out only treated group at 13 weeks post-injection compared to the vehicle treated group (Figs. 46A and 46B). Both a-and b-waves improved in the knock out and replace treated groups compared to the knock out only treated group (Figs. 46A and 46B). The concentration of 3xl0 ¹² vg/ml appeared to be more efficacious.

In sum, the knock out and replace dual AAV vector-injected eyes of non-human primates showed almost complete knockout of the endogenous RHO mRNA and protein, restoration of RHO protein expression in the outer segments via exogenous RHO replacement, and retention of normal photoreceptor structure and function (ERG analysis) compared to the knock out-injected eyes. Of note, the productive editing levels were much higher in non-human primates relative to mice (see Example 11). This data supports the efficacy of the knock out and replace strategy to permanently suppress mutant endogenous RHO and sustain morphological and functional photoreceptor preservation via replacement of exogenous RHO. Example 13: Study testing different ratios and concentrations of the dual AAV vector system in non-human primates A non-human primate model may be utilized to evaluate different ratios and/or concentrations of the knock out and replace dual AAV vector system. Briefly, non-human primates may be subretinally injected adjacent to the macula (Fig.41) with 100 µl one of the following: (1) vehicle or (2) the knock out and replace dual AAV vector system (Fig.40) including Vector 1 encoding SaCas9 under the control of the minimal 625 bp RHO promoter (Vector 1 comprises the sequence set forth in SEQ ID NO:1005) and Vector 2 encoding two RHO-3 gRNAs under the control of U6 promoters and exogenous RHO under the control of the minimal RHO 250 bp promoter (Vector 2 of the knock out and replace dual AAV vector system comprises the sequence set forth in SEQ ID NO:1006). In certain embodiments, the knock out and replace dual AAV vector system may be administered at a total concentration of 6x10 ¹⁰ vg/ml and at a ratio of, for example, 1:1 (3.0x10 ¹⁰ vg/ml (Vector 1) + 3.0x10 ¹⁰ vg/ml (Vector 2)), 1:2 (2.0x10 ¹⁰ vg/ml (Vector 1) + 4.0x10 ¹⁰ vg/ml (Vector 2)), or 1:4 (1.2x10 ¹¹ vg/ml (Vector 1) + 4.8x10 ¹¹ vg/ml (Vector 2)). In certain embodiments, the knock out and replace dual AAV vector system may be administered at a total concentration of 1x10 ¹¹ vg/ml and at a ratio of, for example, 1:1 (0.5x10 ¹¹ vg/ml (Vector 1) + 0.5x10 ¹¹ vg/ml (Vector 2)), 1:2 (0.33x10 ¹¹ vg/ml (Vector 1) + 0.66x10 ¹¹ vg/ml (Vector 2)), or 1:4 (0.3x10 ¹¹ vg/ml (Vector 1) + 0.8x10 ¹¹ vg/ml (Vector 2)). In certain embodiments, the knock out and replace dual AAV vector system may be administered at a total concentration of 3x10 ¹¹ vg/ml and at a ratio of, for example, 1:1 (1.5x10 ¹¹ vg/ml (Vector 1) + 1.5x10 ¹¹ vg/ml (Vector 2)), 1:2 (1.0x10 ¹¹ vg/ml (Vector 1) + 2.0x10 ¹¹ vg/ml (Vector 2)), or 1:4 (0.6x10 ¹¹ vg/ml (Vector 1) + 2.4x10 ¹¹ vg/ml (Vector 2)). In certain embodiments, the knock out and replace dual AAV vector system may also be administered at a total concentration of, for example, 6x10 ¹¹ vg/ml and at a ratio of 1:1 156 (3.0x10 ¹¹ vg/ml (Vector 1) + 3.0x10 ¹¹ vg/ml (Vector 2)), 1:2 (2.0x10 ¹¹ vg/ml (Vector 1) + 4.0x10 ¹¹ vg/ml (Vector 2)), 1:4 (1.2x10 ¹¹ vg/ml (Vector 1) + 4.8x10 ¹¹ vg/ml (Vector 2)). In certain embodiments, the knock out and replace dual AAV vector system may also be administered at a total concentration of, for example, 1x10 ¹² vg/ml and at a ratio of 1:1 (0.5x10 ¹² vg/ml (Vector 1) + 0.5x10 ¹² vg/ml (Vector 2)), 1:2 (0.333x10 ¹² vg/ml (Vector 1) + 0.666x10 ¹² vg/ml (Vector 2)), 1:4 (0.2x10 ¹² vg/ml (Vector 1) + 0.8x10 ¹² vg/ml (Vector 2)). In certain embodiments, the knock out and replace dual AAV vector system may be administered at a total concentration of 3x10 ¹² vg/ml and at a ratio of, for example, 1:1 (1.5x10 ¹² vg/ml (Vector 1) + 1.5x10 ¹² vg/ml (Vector 2)), 1:2 (1.0x10 ¹² vg/ml (Vector 1) + 2.0x10 ¹² vg/ml (Vector 2)), or 1:4 (0.6x10 ¹² vg/ml (Vector 1) + 2.4x10 ¹² vg/ml (Vector 2)). To suppress potential inflammation, the non-human primates may be treated with an immunomodulatory agent, for example, a glucocorticoid (such as, methylprednisolone 80 mg), intramuscularly for four weeks. In certain embodiments, the glucocorticoid may be administered starting on Day-1 and weekly for four injections total. The neural retina of the eyes may be collected and analyzed for the following: non-human primate RHO editing efficiency (analyzed by, e.g., UDiTaS), SaCas9 mRNA and gRNA levels (analyzed by, e.g., RT-qPCR or NanoString), and non-human primate endogenous RHO and exogenous codon optimized (coRHO) mRNA and protein levels (analyzed by, e.g., NanoString and tandem mass spectrometry, respectively). See Section “IX. Methods of Assays” above for the methods of these assays. Example 14: Administration of a gene editing system to a patient in need thereof A human patient presenting with adRP is administered a gene editing system comprising two AAV5-based expression vectors, as described herein. Vector 1 comprises a nucleic acid sequence encoding an S. aureus Cas9 protein, flanked on each site by a nuclear localization sequence under the control of a GRK1 promoter or under the control of a RHO minimal promoter (e.g., 250 bp RHO promoter, 625 bp RHO promoter). Vector 2 comprises a nucleic acid sequence encoding one or more guide RNAs, each under the control of a U6 promoter. The targeting domain of the one or more guide RNAs, independently, is selected from the following sequences: RHO-1: GUCAGCCACAAGGGCCACAGCC (SEQ ID NO:100)

The nucleic acid sequence encoding the guide RNA is under the control of a U6 promoter. Vector 2 further comprises a nucleic acid comprising an upstream sequence encoding aRHO 5’-UTR, aRHO cDNA, and a downstream sequence encoding a 3’UTR, e.g., an HBA1 3’-UTR, under the control of a minimalRHO promoter sequence that comprises a portion of theRHO distal enhancer and a portion of theRHO proximal promoter region. The [promoter]-[5’UTR]-[cDNA]-[3’UTR] sequence of Vector 2 is as follows: Where a guide RNA is used that comprises a targeting domain that binds to a wild- type RHO sequence present in the RHO cDNA, a codon-modified version of the RHO cDNA may be substituted for the RHO cDNA comprised in the nucleic acid construct above. In certain embodiments, Vector 1 may comprise the sequence set forth in SEQ ID NO:9, SEQ ID NO:10, or SEQ ID NO:1005. In certain embodiments, Vector 2 may comprise the sequence set forth in SEQ ID NO:11 or SEQ ID NO:1006. Vector 1 and Vector 2 are packaged into viral particles according to methods known in the art and delivered to the patient via subretinal injection at a dose of up to 300 microliters of 1x10 ¹¹ - 6x10 ¹² viral genomes (vg)/mL. In certain embodiments, the total concentration may be, for example, about 3x10 ¹¹ , 6x10 ¹¹ , 1x10 ¹² , or 3x10 ¹² . In certain embodiments, the Vector 1:Vector 2 ratio may be 1:1, 1:2, or 1:4. The patient is monitored post-administration, and periodically subjected to an assessment of one or more symptoms associated with adRP. For example, the patient is periodically subjected to an assessment of rod photoreceptor function, e.g., by scotopic microperimetry. Within about one year after administration of Vector 1 and Vector 2, the patient shows an amelioration of at least one adRP associated symptom, e.g., a stabilization of rod function, characterized by improved rod function compared to the expected level of rod function in the patient, or in an appropriate control group, in the absence of a clinical intervention. Table 18: gRNAs Providing > 0.1% Editing of RHO Alleles in HEK293T Cells gRNA Targeting Domain (RNA) Targeting Domain (DNA)/ ID Protospacer

Incorporation by Reference

All publications, patents, and patent applications mentioned herein are hereby incorporated by reference in their entirety as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference. In case of conflict, the present application, including any definitions herein, will control.

Equivalents

Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the disclosure described herein. Such equivalents are intended to be encompassed by the following claims.

Additional Sequences

Exemplary sequences that may be used in certain embodiments are set forth below: AAV ITR:

TGCAGGCAGCTGCGCGCTCGCTCGCTCACTGAGGCCGCCCGGGCAAAGCCCGGGCGT CGGGC GACCTTTGGTCGCCCGGCCTCAGTGAGCGAGCGAGCGCGCAGAGAGGGAGTGGCCAACTC CA TCACTAGGGGTTCCT (SEQ ID NO:92)

U6 Promoter: AAGGTCGGGCAGGAAGAGGGCCTATTTCCCATGATTCCTTCATATTTGCATATACGATAC AA GGCTGTTAGAGAGATAATTAGAATTAATTTGACTGTAAACACAAAGATATTAGTACAAAA TA CGTGACGTAGAAAGTAATAATTTCTTGGGTAGTTTGCAGTTTTAAAATTATGTTTTAAAA TG

Attorney Docket No.: 118945.8019.WO00 Ambati et al., Invest Ophthalmol Vis Sci 41(5):1181-1185 (2000a) Ambati et al., Invest Ophthalmol Vis Sci 41(5):1186-1191 (2000b) Amrani et al., Genome Biol.19(1):214 (2018) 35 Bae et al., Bioinformatics 30(10):1473-1475 (2014) Berson et al., N Engl J Med.323(19):1302-1307 (1990) Briner et al., Mol Cell 56(2):333-339 (2014) Burstein et al., Nature.542(7640):237-241 (2017) Casini et al., Nat Biotechnol.36(3):265-271 (2018) 40 Chen et al., Nature.550(7676):407-410 (2017) Cideciyan et al., PNAS 95 (12):7103-8 (1998) Cideciyan et al., PNAS.115 (36):E8547-E8556 (2018) Cong et al., Science.339(6121):819-23 (2013) 203 156624540.2 Daiger et al., Arch Ophthalmol. 125(2):151-8 (2007)

Giannoukos et al., BMC Genomics 19:212 (2018)

Heigwer et al., Nat Methods 11(2): 122-3 (2014)

Hsu et al., Nat Biotechnol 31(9):827-832 (2013)

Jacobson et al., Am .1 Ophthalmol 112(3):256-71 (1991)

Jeon et al., J Neurosci 18(21):8936-46 (1998)

Jiang et al., Nat Biotechnol 31(3):233-239 (2013)

Jinek et al., Science 337(6096):816-821 (2012)

Kim et al., Nat Commun. 8:14500 (2017)

Kleinstiver et al., Nat Biotechnol 33(12):1293-1298 (2015) Kleinstiver et al., Nature 529(7587):490-495 (2016)

Lee et al., Nat Commun. 9(1):3048 (2018)

Li et al., The CRISPR Journal 01:01 (2018)

Maeder et al.. Nat Med. 201925(2):229-233 (2019)

Mali et al., Science 339(6121):823-826 (2013)

Nishimasu et al., Cell 156(5):935-949 (2014)

Nishimasu et al., Cell 162(5): 1113-1126 (2015)

Nishimasu et al., Science. 361(6408):1259-1262 (2018)

Packer et al., J Comp Neurol. 288(1): 165-83 (1989)

Pellissier et al., Mol Ther Methods Clin Dev. 1:14009 (2014)

Ran et al., Cell 154(6): 1380-1389 (2013)

Ran et al., Nature. 520(7546):186-91 (2015)

Strecker et al., Nat Commun. Jan 22;10(1):212 (2019)

Teng et al., Cell Discov. 4:63 (2018)

Wang et al., Plant Biotechnol J. pbi.13053 (2018)

Wikler et al., J. Comp Neurol. 297(4): 499-508 (1990)

Xiao et al. Bioinformatics 30(8): 1180- 1182 (2014)

Yadav et al., Human Molecular Genetics 23(8):2132-2144 (2014) Yan et al., Science 363(6422):88-91 (2019)

Zetsche et al., Nat Biotechnol 33(2): 139-142 (2015)

Zetsche et al., Nat Biotechnol. 35(1):31-34 (2017)