Viral vectors as vaccine platforms: deployment in sight

► Viral-vectored vaccines for veterinary and human use: induction of T cell responses. ► Induction of tailored polyfunctional, site-specific and memory immune response. ► Chimpanzee adenoviruses in humans circumvent pre-existing immunity. ► Success of prime-boost regimen in clinical trials for HIV and malaria. ► New technologies for enhancement of the vectors manufacturing and deployment.A little more than a decade after the explosion of research into recombinant live-attenuated or replication-deficient viruses as vaccine platforms, many viral vector-based vaccines have been licensed for animals. Progress has been slower for humans but 2011 will see the licensure of the first viral-vectored vaccine for humans, against Japanese Encephalitis. In addition a vaccine with a viral-vectored component showed efficacy against HIV infection in humans. Viral-based vaccines have an excellent safety profile but must deal with the potential problem of pre-existing anti-vector immunity. Recent successes reflect diverse improvements such as development of new adenovirus serotypes and better prime-boost approaches, suggesting that many viral vectors are approaching their final years as vaccine ‘candidates’ rather than vaccines