Mucosal immunity and vaccines against simian immunodeficiency virus and human immunodeficiency virus

HIV is primarily transmitted across mucosal surfaces. Thus, a successful vaccine to prevent HIV transmission and infection requires induction of mucosal immune responses. The anti-simian immunodeficiency virus/human immunodeficiency virus (SIV/HIV) antibodies are present in the vaginal secretions of infected individuals. IgG is the major isotype of anti-SIV/HIV antibodies in vaginal secretions. The induction of anti-HIV S-IgA-neutralizing anti-HIV envelope IgG and innate antiviral effector molecules at the sites of mucosal transmission-is considered the most effective strategy to prevent HIV infection by vaccination. There is a clear evidence of antiviral CD8+ T-cell effector function in mucosal tissues. A successful approach in eliciting anti-HIV CD8+ cytotoxic T lymphocytes (CTLs) in uninfected individuals is with the use of recombinant vaccinia virus vector containing HIV-1 env. Priming with recombinant vaccinia and boosting with envelope subunit protein induce both neutralizing antibodies and CTLs. Anti-SIV CTLs are present in the gastrointestinal (GI) tract and vaginal epithelium of SIV-infected rhesus macaques, and anti-HIV CTLs are present in the GI tract and endocervix of HIV-infected patients.