New advances in the molecular biology of hepatitis C virus infection: towards the identification of new treatment targets.

Hepatitis C virus (HCV) causes chronic infection in almost 2% of the world's population. If untreated, chronic carriers can develop severe liver disease including fibrosis, cirrhosis and hepatocellular carcinoma. Until recently, hepatitis C was treated with a combination of pegylated interferon and ribavirin, a treatment which was only partially effective and was plagued with side effects. In 2011 two inhibitors of the virally encoded NS3/4 protease have become part of standard therapy, which have improved treatment rates but can exacerbate the problematic side effects. While the addition of these first directly acting antivirals (DAAs) marks a milestone in anti-HCV therapy, new and improved combinations of drugs are desperately needed. New generations of drugs will have to address genetic variability of HCV and issues of viral resistance. Furthermore, combination therapies have to be tailored to effectively cure patient populations that have traditionally been hardest to treat, including patients with cirrhosis, those receiving liver transplants and individuals who are co-infected with HIV or hepatitis B virus. Since the discovery of HCV a plethora of experimental tools have been developed which enabled detailed analysis of various aspects of the viral life cycle and the interaction of HCV with its human host. Such studies have revealed a growing list of targets for therapeutic intervention, some of which will be discussed in this review.