Neutralization of human immunodeficiency virus type 1 (HIV-1) mediated by parotid IgA of HIV-1-infected patients

Infection with human immunodeficiency virus type 1 (HIV-1) has been shown t o elicit a serum antibody response with neutralizing activity against T cel l line-adapted HIV strains and primary HIV-1 isolates. Mucosal surfaces are the primary route of HIV-1 infection. Evidence is presented here for the p resence of HIV-neutralizing antibodies in secretions. Infection of mucosal cells with HIV stimulates systemic and mucosal immune responses and results in the generation of neutralizing antibodies. Serum IgG and IgA neutralize HIV-1(MN) infection of susceptible T cell lines; serum IgG inhibits more e ffectively. Mucosal IgA purified from parotid saliva of HIV-1-seropositive individuals could neutralize both a T cell line-adapted strain and a primar y isolate, The neutralizing activity of IgA was not directed against the an ti-third-variable-loop or the anti-ELDKWA epitope. Thus, the specificity of mucosal IgA for HIV-1 neutralization epitopes remains to be determined and may provide insight into development of a mucosal vaccine.