The immunopathogenesis of HBV infection

Clinical manifestations of hepatitis B virus (HBV) infection are a balance between viral and host factors. The immune response against any virus consists of a coordinated defence of innate immunity and acquired, virus-specific immunity. In acute HBV, immune responses associated with recovery include vigorous, polyclonal CD4 T cells directed against multiple epitopes within HBV; antibodies directed against surface envelope proteins (anti-HBs), the development of which requires the presence of a CD4 response; and HBV-specific cytotoxic T lymphocytes (CTLs). HBV-specific CTLs can induce death of infected hepatocytes as well as produce cytokines. Most individuals with acute HBV recover without evidence of massive liver destruction; this, plus evidence from transgenic animal models, suggests that these cytokines produced by T cells play an important role in controlling HBV replication. Individuals who fail to mount a vigorous response in acute HBV develop chronic infection. In these cases, the persisting ineffective immune response appears to be responsible for liver damage and is likely to initiate the process of hepatic fibrosis. Based on our current understanding of the immune response in acute and chronic HBV, several groups are investigating the prospect of manipulating the immune response in chronic HBV.