isolation, subtype determination, cloning and expression of hbsag gene from an iranian carrier in saccharomyces cerevisiae

the hepatitis b surface antigen ( hbsag) gene was isolated from an iranian hbeag positive carrier by pcr. the gene was cloned in puc19 for sequencing and pyes2 for expression in saccharomyces cerevisiae, which pnf1 and pdf3 constructs were made respectively. the sequencing data showed that the isolated hbsag gene shared more than 90% homology with the ayw subtype. the pdf3 was transferred into the yeast strain and expression of the hbsag was induced. yeast-derived hbsag was purified by immunoaffinity chromatography and checked by elisa, western blot analysis and con firmatory elisa. the immunogenicity test in mice showed that injection of the yeast-derived re combinant hbsag could induce the immunologic response against the antigen. 320 fold dilution of the mouse serum was positive for anti-hbsag. the amount of hbsag expressed in yeast constitute 1% of the total cell soluble protein.