B69-02 Targeting Lung Tissue Resident Immunity via Intramuscular Vaccination for Protection Against Mycobacterium Tuberculosis

Abstract Background/Rationale Tuberculosis (Tb) kills approximately 1.3 million people a year, making it the leading cause of death from a single infectious agent (Mycobacterium tuberculosis, Mtb) worldwide. Intradermally administered Bacille Calmette-Guerin (BCG) is the only licensed Tb vaccine; however, BCG has limited efficacy in adults and vaccination site reactions. Additional issues include exclusion of immunocompromised/pregnant individuals, waning protection with age, and insufficient mucosal immunity. An improved Tb vaccine is needed to confer long lasting protection for all individuals. A novel adjuvanted vaccine that induces mucosal immunity could confer greater protection. Design/Methods We hypothesized that intramuscular (IM) vaccination with adjuvants double mutant Escherichia coli heat-labile toxin (dmLT) and a bacterial outer membrane vesicle-derived adjuvant (T-vant) would induce both humoral and cellular immune responses, driving tissue resident immunity in the lung via non-mucosal immunization. Female C57BL/6 mice will be vaccinated IM with either model antigen alone or model antigen with the adjuvant cocktail in a prime-boost fashion three weeks apart. Two weeks post boost, mice will be intravenously injected with CD45 antibody to differentiate cells in circulation from tissue resident cells. Draining lymph nodes, spleens, and lungs will be harvested and stained with antigen-specific MHCII tetramer to identify CD4+ T cells that are vaccine-specific. Flow cytometry will allow for identification of cells that are tissue resident (IV CD45-CD69+P2X7R+), and serum and bronchoalveolar lavage fluid will be collected to assess antibody titers. Results In comparison to other parenteral and mucosal routes, IM vaccination generated the highest number of vaccine specific CD4+ T cells. Following IM immunization, we observed significantly higher numbers of tissue resident vaccine-specific CD4+ in the lung of combination-adjuvant vaccinated mice than naïve or antigen alone groups. These cells preferentially displayed a TH1/TH17 phenotype, which are key correlates of protection for Mtb infection, and produced key cytokines IL-17, IFNγ, and TNF-α. Conclusion Our preliminary findings suggest that our combination adjuvanted vaccine produces lung-resident immune responses that could provide increased protection against lung infections. We hope to utilize this in developing novel vaccines for tuberculosis that target correlates of protection for lasting protection for all individuals. This abstract is funded by: NIH