Immunity and immune evasion in Hepatitis C virus infection

Abstract

Hepatitis C virus (HCV) is an RNA virus which chronically infects an estimated 200 million people worldwide. Infection with HCV proceeds to chronicity in 80% of cases, and can be associated with the development of liver cirrhosis, fibrosis and hepatocellular carcinoma. The failure of immune responses to eliminate the virus is poorly understood, however viral clearance is associated with the generation of vigorous virus-specific CD4+ and CD8+ T cell responses directed against a broad range of viral epitopes. In contrast, patients who become persistently infected mount weaker responses which are directed against a limited range of epitopes. In addition, virusspecific type 1 regulatory T cells and elevated frequencies of CD4+ CD25high FoxP3+ regulatory T (Treg) cells have been detected in chronically infected patients.