Biosynthesis of the recombinant middle surface antigen of the human hepatitis B virus in silkworm larvae

Human hepatitis B virus middle surface antigen (M-HBsAg) is an envelope protein used as a basis for constructing vaccines and test systems detecting the virus. The M-HBsAg cDNA was inserted in transfer vector pBK273 under the transcriptional control of the polyhedrin gene promoter to obtain recombinant pBHep-2. Cotransfection with pBHep-2 and the wild-type Bombix mori NPV DNA yielded a recombinant baculovirus, rBmNPVHep, with the M-HBsAg cDNA controlled by the polyhedrin gene promoter. Infection of B. mori larvae with rBmNPVHep led to expression of the foreign gene; recombinant M-HBsAg accumulated predominantly (to more than 90% its total content) in the fat body of larvae.