PURPOSE: To obtain a stable recombinant hepatitis B virus surface protein useful for the production of a vaccine without using any enzyme inhibitor by destroying the recombinant yeast cells expressing the surface antigen in a high pH buffer liquid, heat treating to obtain a clarified extract, and adsorbing the protein on to a wide pore silica.

CONSTITUTION: This method for stabilizing a recombinant hepatitis B virus surface protein is obtained by destroying an yeast integrated with a DNA encoding the surface protein of the hepatitis B virus by means of recombinant DNA technology in a buffer liquid of approximately pH 9-12, e.g. 0.5 mol. tris buffer of approximately pH 10, adjusting pH of the mixture approximately at 10.5, heattreating at 40-60°C for 30 min, cool to 10°C, then adding a surfactant such as triton X-100, etc., removing undesirable yeast cell fragments and the surfactant by means of a centrifuge, a precise filtration, etc., adjusting pH of the extract approximately at 7.5-8.0, adsorbing the surface protein on to wide pore silica beads (particld diameter: 30-130 μ, pore diameter; 1000-1500 ), eluting the protein and concentrating the eluted liquid to obtain the hepatitis B surface protein.