Current status of vaccine therapy for hepatitis c infection

Hepatitis C virus (HCV) infection affects approximately 3% of the world’s population and nearly 3 million people in the United States. After a usually silent acute phase, chronic infection develops in 50% to 85% of patients and leads to progressive liver injury in 10% to 30% of patients over 10 to 30 years. HCV infection is the leading indication for liver transplantation in the United States. The mechanisms by which HCV establishes persistence in the human host remain an area of active investigation. Since the initial cloning of HCV, much progress has been made in our understanding of the HCV life cycle, immunological determinants in the outcome of HCV infection, and technical approaches relevant to vaccine development. In natural infection, HCV-specific T-cell response correlates strongly with HCV clearance, whereas neutralizing antibody response does not. However, both humoral and cellular components of the adaptive immune response (supplemented by innate immune activation) will likely be required for a successful vaccine approach. This review will discuss aspects of HCV, protective immunity, various considerations regarding HCV vaccine development, and vaccine approaches currently in development.