M cell DNA vaccination for CTL immunity to HIV

To facilitate invasion, reovirus has evolved to attach to M cells, a specialized epithelium residing within the follicle-associated epithelium that covers mucosal inductive tissues. Thus, we questioned adapting reovirus protein sigma1 to ferry DNA vaccines to the mucosa to immunize against HIV. Three expression plasmids encoding HIV(Ba-L) gp160, cytoplasmic gp140, and secreted gp140 were tested in mice as protein sigma1-poly-L-lysine-DNA complexes (formulated vaccine) via the intranasal route. Evaluation of cell-mediated immunity showed that the formulated gp160 DNA vaccine was more effective for stimulating envelope (Env)-specific CTL responses in lungs, lower respiratory lymph nodes (LN), cervical LN, submaxillary gland LN, and spleens. Three doses of vaccine were required for CTL responses, and intranasal naked DNA immunizations were ineffective. The greatest CTL activity was observed between weeks 8 and 10 for gp160-vaccinated mice, and activity remained detectable by week 16. These Env-specific CTL responses were perforin dependent in peripheral tissues, but mostly Fas dependent in the lungs. These Env-specific CTLs also produced IFN-gamma. Mice vaccinated with the formulated gp160 DNA vaccine showed potent antiviral immunity against vaccinia virus-env replication in ovaries. Thus, compared with live vectors, protein sigma1-mediated DNA delivery represents an alternative mucosal formulation for inducing cellular immunity against HIV-1.