Hepatitis C vaccines

It is estimated that 3% of the world's population is chronically infected by the hepatitis C virus (HCV). Most infections become chronic and, over time, evolve into chronic hepatitis. The most unwanted complication of chronic hepatitis is cirrhosis, a massive liver fibrosis, that can lead to liver failure and hepatocellular carcinoma. Indeed, hepatitis C is the leading reason for liver transplantation worldwide. However, liver transplantation is not a cure for HCV, as virus recurrence is universal. Current medical therapy for chronic hepatitis C, consisting of a combination of pegylated interferon- α (Peg-IFN) and ribavirin, eradicates the virus in fewer than half of treated patients and is plagued with serious side effects. Although newly developed direct antiviral agents targeting HCV proteins have been shown to improve virological response, toxicity and resistance remain major challenges. There is, therefore, a pressing need to develop vaccination strategies aimed at preventing and possibly eradicating HCV infection. The scientific and clinical challenges that must be addressed and overcome in developing an efficacious HCV vaccine are substantial but may not be insurmountable. In the last years, considerable progress has been made in the understanding of HCV virology, pathogenesis, and immunology. Data indicating the existence of natural immunity against the hepatitis C virus and vaccine efficacy in the chimpanzee challenge model allow optimism for the development of an effective vaccine against this heterogeneous pathogen that is responsible for much of the chronic liver disease around the world.