A mucosal vaccine against Chlamydia trachomatis generates two waves of protective memory T cells

Genital Chlamydia trachomatis (Ct) infection induces protective immunity that depends on interferon-γ–producing CD4 T cells. By contrast, we report that mucosal exposure to ultraviolet light (UV)–inactivated Ct (UV-Ct) generated regulatory T cells that exacerbated subsequent Ct infection. We show that mucosal immunization with UV-Ct complexed with charge-switching synthetic adjuvant particles (cSAPs) elicited long-lived protection in conventional and humanized mice. UV-Ct–cSAP targeted immunogenic uterine CD11b[superscript +]CD103[superscript –] dendritic cells (DCs), whereas UV-Ct accumulated in tolerogenic CD11b[superscript –]CD103[superscript +] DCs. Regardless of vaccination route, UV-Ct–cSAP induced systemic memory T cells, but only mucosal vaccination induced effector T cells that rapidly seeded uterine mucosa with resident memory T cells (T[subscript RM] cells). Optimal Ct clearance required both T[subscript RM] seeding and subsequent infection-induced recruitment of circulating memory T cells. Thus, UV-Ct–cSAP vaccination generated two synergistic memory T cell subsets with distinct migratory properties.National Institutes of Health (U.S.) (Grant U54-CA119349)National Institutes of Health (U.S.) (Grant U54-CA151884)National Institutes of Health (U.S.) (Grant R37-EB000244)Prostate Cancer FoundationMIT-Portugal ProgramNational Science Foundation (U.S.). Graduate Research Fellowshi