Vaccination of infant macaques with a recombinant modified vaccinia virus Ankara expressing the respiratory syncytial virus F and G genes does not predispose for immunopathology.

We have evaluated the safety and immunogenicity of a recombinant modified vaccinia virus Ankara (MVA) vector expressing the respiratory syncytial virus (RSV) fusion (F) and attachment (G) proteins in infant macaques. Animals were vaccinated twice and 4 months later challenged with RSV. Although vaccination did not predispose for immunopathology upon challenge, we were also unable to demonstrate protection. Since vaccination had resulted in priming for secondary immune responses upon challenge, we suggest that vaccination efficacy will have to be improved by using MVA in a prime-boost strategy.