A novel adjuvanted vaccine protects against Chlamydia infection in mice 2095

Abstract Description Mucosal surfaces are the primary site of pathogen encounter. This is true for the female reproductive tract (FRT), which acts as the entry point for the intracellular bacterium Chlamydia. In 2022, the United States had reported over 1.6 million cases of Chlamydia, which made it the most reported STI that year. While inducing protective immunity at these sites through mucosal immunizations is attractive, vaccine hesitancy and the complicated nature of an intravaginal vaccine make this difficult. Prior work in our lab has shown that we can direct both cellular and humoral immunity to mucosal sites via non-mucosal (parenteral) vaccination using the double mutant heat labile toxin (dmLT). Additionally, a bacterial outer membrane vesicle derived adjuvant (T-vant) elicits durable and broad immune responses. We hypothesized that a Chlamydial vaccine adjuvanted with a combination of dmLT and T-vant plus the major outer membrane protein (MOMP) from Chlamydia would provide robust protection against infection at the FRT, even when delivered parenterally. We found that this vaccine elicited significantly elevated MOMP specific antibodies and tissue resident CD4 T cell responses in the lymph nodes and, importantly, the FRT. Notably, we observed a significant decrease in bacterial burden in the FRT in vaccinated mice that correlated with reduced pathology demonstrating the effectiveness of this vaccine. These findings demonstrate that using this adjuvant combination can Funding Sources NIH 1R01AI166756-01A1 Topic Categories Vaccines and Immunotherapy (VAC)