The challenges of RSV vaccines. Where do we stand?

The most realistic way to control RSV infection would be the development of an effective and safe vaccine. A formalin-inactivated RSV vaccine was evaluated in infants and children in the 1960's which disappointingly was linked with aggravation of RSV disease following the natural infection. Two candidate vaccines with purified protein F, have been tested, in humans and have been considered safe and somewhat immunogenic in seropositive persons providing different levels of protection against RSV re-infection. Live attenuated RSV vaccines induce local and systemic immunity without producing enhanced disease upon exposure of the vaccinee to the wild virus. Plasmid DNA vaccines were also evaluated in mice and elicited balanced systemic and pulmonary Th1/Th2 response without inducing an atypical pulmonary inflammatory reaction following the RSV challenge in cotton rats. Gene gun vaccination, a method to overcome the problem of DNA quantity, has been associated with a Th-2 biased response. Recent patents, such as plant vaccines, combined vaccines, attempted to invent new techniques for the generation of safe and effective vaccines. The new RSV vaccines should overcome many obstacles before being established as effective vaccines for the control of RSV infections especially for the young infants who are more susceptible to the virus.