Mycobacterium tuberculosis ESAT-6 antigen immunogenicity in Owl Monkeys

Several ESAT-6-based vaccines have been widely studied in different animal models, presenting potent ability to induce both cellular and humoral responses. As ESAT-6 is a well-characterized mycobacterial antigen, its capacity to induce immune responses in a nonhuman primate model has been evaluated. The immunization of recombinant ESAT-6 (rESAT-6) in Aotus nancymaae monkeys has elicited a strong cellular response, not just to rESAT-6, but also to the native protein present in Mycobacterium tuberculosis culture filtrate proteins measured as [3H]thymidine incorporation in lymphocyte proliferation assays. High humoral response was also observed, having antibody titers of 1:12,800 directed towards rESAT-6. The protein’s multi-epitope nature was further demonstrated since several peptide sequences were specifically recognized at both cellular and humoral level. The high immunogenicity observed, as well as the relatively high characterization of the Aotus’ immune system at molecular level, are two advantage to propose Aotus nancymaae as animal model for studying M. tuberculosis infection; however, our results reveal an animal-to-animal variation in response to vaccination, this could be a disadvantage.