Immunology of hepatitis B and hepatitis C virus infections.

Hepatitis B (HBV) and hepatitis C (HCV) viruses are the two major causes of chronic liver inflammation worldwide. Despite distinct virologic features, both viruses are preferentially hepatotropic, not directly cytopathic, and elicit liver diseases that share several aspects of their natural history. HBV and HCV infections also share some important features of the adaptive antiviral immune response. We describe the innate immune response in the early phase following infection, and how these early events may influence the development of the adaptive immune response in these two important viral infections. The mechanisms by which high levels of viral antigens, liver immunological features, the presence of regulatory T cells and impaired dendritic cell functions may maintain the HBV- and HCV-specific immunological failure, characteristic of chronic hepatitis B and C patients, are also evaluated.