Biodefense research priorities should include development of immunotherapeutics and effective vaccines against biological warfare agents. Both cellular and humoral immune responses may play a role in immunity to anthrax, plague and tularemia. Vy2V82 T cells exist only in primates and constitute 60-95% of total human y5 T cell population in the blood. We and others have demonstrated that phosphoantigen-specific Vy2V82 T cells can function as both innate and adaptive immune cells, and contribute to adaptive immunity to acutely fatal form of tuberculosis. Our new studies indicate that B. anthracis can indeed produce phosphoantigen stimulating Vy2V52 T cells and prime these cells for cross-reactive memory-type response after subsequent infection with phosphoantigen-producing mycobacteria. Importantly, phosphoantigen HMBPP treatment of monkeys can expand Vy2V52 T cells from <1% to >70% in total circulating T cells. HMBPP-activated Vy2V82 T cells readily migrate to the lung and confer protection against pulmonary mycobacterial infection in macaques. We hypothesize that phosphoantigen HMBPP-mediated activation of Vy2V52 T cells can greatly boost innate and adaptive immune responses to B. anthracis, Y. pestis and F. tularensis, and confer protection against fatal inhalational anthrax, plague and tularemia. We further hypothesize that a combined vaccine comprised of both phosphoantigen and protein antigen can target 4 immune components: Vy2V52 T cells, CD4 T helpers, CDS T killers, and antibodies, and therefore can be more efficient for immunization and vaccine-induced protection against anthrax, plague and tularemia. To facilitate testing these hypotheses, we have worked out clinical and immunological aspects of HMBPP treatment regimens, and developed vaccine platform technology for constructing recombinant BCG and Listeria vaccine vectors. To test our hypothesis and ultimately develop recombinant vaccines against anthrax, plague and tularemia, we will: I. Assess HMBPP regimens for immunotherapeutic effects on fatal inhalational anthrax, plague, and tularemia in nonhuman primates. II. Construct and characterize recombinant BCG and recombinant attenuated Listeria vaccine vectors expressing B. anthrax PA, Y. pestis F1 or F. tularensis Ag. III. Compare oral and intradermal immunization routes for vaccine-elicited immune responses in monkeys that receive heterologous prime-boost vaccination with recombinant BCG and Listeria vaccine vectors expressing B. anthracis PA, Y. pestis F1, or F. tularensis Ag. IV. Determine whether oral heterologous prime-boost vaccination with recombinant BCG and Listeria vaccine vectors expressing PA, F1, or tularemia Ag can confer protective immunity against fatal inhalational anthrax, plague and tularemia in nonhuman primates.
