[Use of baculovector for the expression of HBsAg gene in insect cells]

Based on the information of molecular biology of Autographa californica Nuclear Polyhedrosis virus (AcNPV), a recombinant transfer plasmid pAcMV was constructed by molecular procedures included using two synthetic localized probes, which provided an inserted position linked with BamHI sequences nearly at polyhedrin initiating ATG codon. Then an expression vector pAcMV-HBsAg was reconstructed, it contained HBsAg gene from subclone pYPSS-1 derived from adwserotype of HBV. The recombinant virus containing HBsAg gene was isolated and purified through 3 cycles plaques and hybridization experiment after cotransfection of Spodoptera frugiperda cells with DNA of pAcMV-HBsAg and AcNPV. The expression of HBsAg gene in S. frugiperda cells infected with recombinant virus AcRV-HBsAg was identified by ELISA as haemagglutination tests. The yield of HBsAg excreted from S. frugiperda cells (an appropriate density usually between 1-2 X 10(6) cells/ml) after 48-72 h infected with AcRV-HBsAg was 4-8 mg/L. HBsAg harvested from the infected culture medium was shown immunoelectromicroscopy to be composed of spherical particles of about 22 nm diameter. Using this purified HBsAg, Bal b/c mice was immunized, the titer of anti-HBsAg serum measured measured by RIA was similar to that of purified HBsAg from human blood. Stable recombinant virus was isolated and could be shown to replicate in corn borer (Ostrinia nubilalis) larvae. All of these results can be expected that this expression vector system will be commercially developed to its fullest potential for diagnosis and vaccine HBsAg.