Construction and expression of indonesian hepatitis B core antigen (HBcAg) in Lactococcus lactis as potential therapeutic vaccine

The hepatitis B core antigen protein (HBcAg) may induce proliferation of B, T, and cytotoxic T cells; induce immune responses; and provide T-cell resources for antibody responses after vaccination (Freivalds et al., 2011). Thus, HBcAg may be used as a therapeutic vaccine in patients with chronic hepatitis B virus (HBV) infection. This article describes a study on the construction and expression of HBcAg in Lactococcus lactis by the nisin-controlled expression (NICE) system. An HBcAg gene, the HBV subgenotype B3 that is dominant in Indonesia, was successfully cloned into a pNZ8148 vector and resulted in the formation of the transformant L. lactis NZ3900 pNZ818-HBcAg. The HBcAg protein measured 21 kDa. Induction with 10 ng/ml nisin significantly increased the concentration of the expressed protein. Western blotting and dot blot hybridization analysis indicated that the HBcAg proteins confirmed the expression of an antibody, with potential to become an HBV therapeutic vaccine.