Analysis of humoral immune responses in rhesus macaques vaccinated with attenuated SIVmac239Deltanef and challenged with pathogenic SIVmac251.

Background: To determine the correlation between protection and humoral immune response against simian immunodeficiency virus (SIVmac251), 11 macaques were immunized with live-attenuated SIVmac239Deltanef either intravenously or via the tonsils and exposed to SIVmac251 after either 6 or 15 months along with unvaccinated controls.

Results: Independent of the route of vaccine application, viremia was significantly reduced in vaccinees compared with controls 2 weeks post-challenge. Concomitantly, viremia correlated inversely with SIV-specific IgG, complement-mediated lysis and neutralizing antibodies and these parameters seemed to contribute to reduced viremia.

Role of complement and antibodies in controlling infection with pathogenic simian immunodeficiency virus (SIV) in macaques vaccinated with replication-deficient viral vectors.

Background: We investigated the interplay between complement and antibodies upon priming with single-cycle replicating viral vectors (SCIV) encoding SIV antigens combined with Adeno5-SIV or SCIV pseudotyped with murine leukemia virus envelope boosting strategies. The vaccine was applied via spray-immunization to the tonsils of rhesus macaques and compared with systemic regimens.

Results: Independent of the application regimen or route, viral loads were significantly reduced after challenge with SIVmac239 (p < 0.