Latent antigen vaccination in a model gammaherpesvirus infection

Vaccines that can reduce the load of latent gammaherpesvirus infections are eagerly sought. One attractive strategy is vaccination against latency-ass ociated proteins, which may increase the efficiency with which T cells reco gnize and eliminate latently infected cells. However, due to the lack of tr actable animal model systems, the effect of latent-antigen vaccination on g ammaherpesvirus latency is not known. Here we use the murine gammaherpesvir us model to investigate the impact of vaccination with the latency-associat ed M2 antigen. As expected, vaccination had no effect on the acute lung inf ection. However, there was a significant reduction in the load of latently infected cells in the initial stages of the latent infection, when M2 is ex pressed. These data show for the first time that latent-antigen vaccination can reduce the level of latency in vivo and suggest that vaccination strat egies involving other latent antigens may ultimately be successfully used t o reduce the long-term latent infection.