Recombinant Modified Vaccinia Ankara (MVA) effectively boosts DNA-primed HIV-specific immune responses in humans despite pre-existing vaccinia immunity.

Author(s): Gudmundsdotter L, Nilsson C, Brave A, Hejdeman B, Earl P, Moss B, Robb M, Cox J, Michael N, Marovich M, Biberfeld G, Sandstrom E, Wahren B

Affiliation(s): Karolinska Institutet and Swedish Institute for Infectious Disease Control, Stockholm, Sweden. L.gudmundsdotter@smi.se

Publication date & source: 2009-07-16, Vaccine., 27(33):4468-74. Epub 2009 May 29.

Publication type: Randomized Controlled Trial; Research Support, Non-U.S. Gov't

The presence of vector-specific immune responses may hamper the induction of responses to a foreign antigen encoded by the vector. We evaluated the impact of pre-existing immunity to vaccinia virus on the induction of HIV-specific responses after immunization of healthy volunteers with a HIV-1 DNA prime-MVA boost vaccine. Following three priming immunizations with HIV-1 DNA plasmids, the volunteers were boosted with a single injection of recombinant MVA encoding HIV-1 proteins. Pre-existing immunity to vaccinia virus did not reduce the proportion of individuals who responded to HIV-1, but did lower the magnitude of responses. Our results suggest that vaccinia-based vectors can be used to efficiently induce immune responses to vectored HIV-1 antigens, even in individuals with pre-existing immunity to vaccinia virus.