PURPOSE: To provide a nucleic acid sequence to code a chicken anemia virus(CAV)-related polypeptide to produce a vaccine to give immunosensitivity for CAV to poultry and to produce a diagnostic test drug.

CONSTITUTION: This invention provides a nucleic acid sequence having the genetic information of chicken anemia virus(CAV), especially a sequence containing three genomic regions which encode a viral polypeptide. The invention also provides its expression system, expression polypeptide, vaccine against CAV infection, its production, its preventing method and test kit useful to detect chickens infected with CAV.