Challenges for development of hepatitis C virus vaccines

Impediments to the development of a hepatitis C virus (HCV) vaccine are reviewed. Foremost is the perception that the limited transmissability of HCV, and reduced spread by blood‐associated routes, make this a low priority target. It is argued that such a vaccine may have an important therapeutic use in the treatment of chronic HCV carriers of which an estimated 30 million exist worldwide. An HCV vaccine would also have prophylactic use in multivalent (hepatitis) vaccines, and in the developing world. An effective HCV vaccine vaccine will not be easy to develop. The high variability of the viral proteins, especially that of the envelope proteins, provide a major challenge. The association of HCV with very low density lipoproteins renders a major proportion of the virions non‐neutralizable, a further challenge. It may be necessary to design an HCV vaccine which acts primarily through the generation of cytotoxic lymphocytes reactive with conserved epitopes displayed on the surface of infected cells.