Expression of S and pre s2+s Hepatitis B surface antigens in mammalian Cos-7 cell line

Hepatitis B virus (HBV) is a serious global health problem. The development of a safe and effective vaccine would help infection prevention. Previous hepatitis B vaccine production involved the isolation of the noninfectious particle from chronic HBV carriers. DNA recombinant technology has been used for vaccine production without having been contaminated with blood-born infectious agents. Vaccine production in mammalian cells has the advantage of being correctly modified and folded in comparison to other lower hosts. The surface protein coding genes, S (Major protein) and pre s2+s (Middle protein) of hepatitis B virus (HBV), were amplified from the mother plasmid containing the adr serotype virus genome. The s and pre s2+s amplicons were separately cloned in pBlueskript IIks(+) vector as pNM-sa2 and pNM-Psa2 intermediates respectively, then released and recloned in pcDNA3 mammalian expression vector. The correct pNM-Sb2 and pNM-Psb2 constructs containing s and pre-s2, respectively, were used to transfect the mammalian Cos-7 cell line. The major and middle proteins were secreted by this cell line and collected from the culture medium. Some features of gene cloning strategy and expression of these proteins are discussed.