Viruses — from pathogens to vaccine carriers

Vaccination is mankind's greatest public health success story. By now vaccines to many of the viruses that once caused fatal childhood diseases are routinely used throughout the world. Traditional methods of vaccine development through inactivation or attenuation of viruses have failed for some of the most deadly human pathogens, necessitating new approaches. Genetic modification of viruses allows not only for their attenuation but also for incorporation of sequences from other viruses, turning one pathogen into a vaccine carrier for another. Recombinant viruses have pros and cons as vaccine carriers, as discussed below using vectors based on adenovirus, herpesvirus, flavivirus, and rhabdovirus as examples.

► Ad vectors are safe, easy to construct, and versatile.
► Herpesvirus vectors induce sustained effector and effector memory CD8+ T cell responses.
► YF-based vaccines induce a potent innate immune response and are both safe and immunogenic.
► VSV-based vectors are versatile, and easily constructed.