IL-15 as memory T-cell adjuvant for topical HIV-1 DermaVir vaccine

IL-7 and IL-15 are key cytokines involved in the generation and maintenance of memory CD8+ T-cells. We evaluated these cytokines as molecular adjuvants for topical HIV-1 DermaVir vaccine. We found that mice receiving DermaVir formulated with HIV-1 Gag plasmid in the presence of IL-7- or IL-15-encoding plasmid significantly enhanced Gag-specific central memory T-cells, as measured by a peptide-based cultured IFN-γ ELISPOT. Additionally, IL-15 significantly improved DermaVir-induced Gag-specific effector memory CD8+ T-cell responses, measured by standard IFN-γ ELISPOT. In a DermaVir prime/vaccinia vector boost regimen, the inclusion of IL-15 together with DermaVir significantly improved Gag-specific effector memory T-cell responses. Our study demonstrates that IL-15 is more potent than IL-7 in enhancing HIV-1-specific central memory T-cells induced by topical DermaVir. IL-15 adjuvanted DermaVir might be an alternative prime in a prophylactic vaccine regimen.