Therapeutic vaccination to treat chronic infectious diseases: current clinical developments using MVA-based vaccines.

A famous milestone in the vaccine field has been the first successful vaccination against smallpox, in 1798, by Edward Jenner. Using the vaccinia cowpox virus, Jenner was able to protect vaccinees from variola or smallpox. The Modified Virus Ankara (MVA) poxvirus strain has been one of the vaccines subsequently developed to prevent smallpox infection and was selected by the US government in their Biodefense strategy. Progress in molecular biology and immunology associated with MVA infection has led to the development of MVA as vaccine platform, both in the field of preventive and therapeutic vaccines. This later class of therapeutics has witnessed growing interest that has translated into an increasing number of vaccine candidates reaching the clinics. Among those, MVA-based therapeutic vaccines have addressed four major chronic infections including viral hepatitis, AIDS, human papillomavirus-linked pathologies and tuberculosis. Clinical trials encompass phase 1 and 2 and have started to show significant results and promises.