Induction of vaginal-resident HIV-specific CD8 T cells with mucosal prime-boost immunization.

Tissue-resident memory (TRM) CD8 T cells survey a range of non-lymphoid mucosal tissues where they rapidly mediate clearance of viral infections at the entry portals. Vaccines that establish CD8 TRM cells in the cervicovaginal mucosa hold promise for effective immunity against sexually transmitted HIV. We demonstrate that HIV-specific CD8 TRM cells can be established in the murine vaginal mucosa using a combined intranasal and intravaginal mucosal immunization with recombinant influenza-HIV vectors. Using in situ tetramer immunofluorescence microscopy, we found that this mucosally administered prime-boost immunization also resulted in the durable seeding of CD8 T cells in the frontline vaginal epithelial compartment as opposed to the vaginal submucosa. Upon cognate antigen recognition within the vaginal mucosa, these HIV-specific CD8 TRM cells rapidly initiated a tissue-wide state of immunity. The activation of HIV-specific CD8 TRM cells resulted in the upregulation of endothelial vessel addressin expression and substantial recruitment of both adaptive and innate immune cells in the vaginal mucosa. These findings suggest that the epithelial localization of HIV-specific CD8 TRM cell populations and their capacity to rapidly activate both arms of the immune system could significantly augment frontline defenses against vaginal HIV infection.