Chemokine receptor-mediated delivery of mycobacterial MPT51 protein efficiently induces antigen-specific T-cell responses.

Here we evaluated the effects of immunization with a DNA vaccine encoding a fusion protein consisting of macrophage inflammatory protein-1alpha (MIP-1alpha) and MPT51 (a major secreted protein from Mycobacterium tuberculosis) on induction of specific CD8+ T cells. The DNA vaccine encoding the fusion protein could induce significantly higher number of the antigen-specific CD8+ T cells in mice than DNA vaccine encoding MPT51 alone. Also, splenocytes from mice immunized with the fusion DNA vaccine expressed higher level of IFN-gamma mRNA and protein upon stimulation with an epitope peptide derived from MPT51 than those from mice immunized with a mixture of two DNA vaccines encoding either MPT51 or MIP-1alpha. These results suggest that DNA vaccine encoding MIP-1alpha-antigen fusion protein is able to be efficiently internalized into antigen-presenting cells via the chemokine receptor and induce higher level of antigen-specific CD8+ T-cell responses.