Replication deficient human adenovirus vector serotype 19a/64: Immunogenicity in mice and female cynomolgus macaques.

The human adenovirus type 19a/64 (hAd19a) is a rare serotype in the human population that transduces human dendritic cells (DCs) and human muscle cells more efficiently than the well-characterized human adenovirus type 5 (hAd5). To further characterize the potential of this vector as a vaccine we designed replication deficient hAd19a, hAd5 and MVA vectors expressing a papillomavirus (PV) antigen fused to the human MHC class II associated invariant chain T cell adjuvant (hIi) and investigated their immunogenicity in vivo in mice and cynomolgus macaques. We initially showed that the hIi encoded in the hAd5 enhanced PV specific CD8+ T cell responses in mice. The T cell responses induced after hAd19a vaccination was similar to those induced by hAd5 vaccination. The hAd19a induced responses were not reduced in presence of preexisting Ad5 immunity in mice. In macaques both vaccines were equally potent at inducing CD8+ T cells after MVA boost, while the level of CD4+ T cell responses were found to be broader in hAd19a primed animals. These data demonstrate the potential of hAd19a as an alternative vector to hAd5 to elicit potent T cell responses to PV.