Acta Univ Latv (2004) 676: 39–51

Synthesis of all hepatitis B structural proteins in the Semliki Forest virus expression system

Abstract

All structural genes of human hepatitis B virus (HBV), subtype ayw, have been expressed in the Semliki Forest virus (SFV) expression vectors pSFV1 and pSFV-C, allowing direct and SFV coredependent expression of foreign genes, respectively. Three variants of HBV surface genes (large, middle and small), as well as the core gene were amplified by PCR technique as independent units and fusions with the SFV core protein gene, cloned in both SFV vectors and expressed in BHK-21 cell culture as single proteins or in different combinations. Maximal production of HBV proteins was achieved using pSFV/C vectors where target products were obtained after processing of SFV core-HBV protein fusions. After infection of the cultured BHK cells with recombinanat SFV-HBV viruses, the expression of all HBV structural genes was detected by immunocytochemistry. Electron microscopy revealed the formation of virion-like particles in the case of simultaneous expression of HBV surface and core genes. This efficient expression system of HBV subunits will be applied for the elucidation of molecular details of HBV assembly, structure and entry.