Clinical observations show that some people are "resistant" to HIV, ie they do not become infected despite repeated sexual exposure to the virus. The "resistance" to HIV exposed but uninfected partners may be due to the absence of infection of target cells in the mucosa of the host, or to elimination of HIV or of infected cell during effective infection. Biological factors that govern individual resistance to HIV remain poorly understood. An immune response directed against cervicovaginal HIV antigens, including viral envelope glycoproteins has been described in a small number of HIV-negative women sexually exposed to the virus and resistant to infection. These observations demonstrate that there is a compartmentalization of the mucosal immune response of women, which can be induced against HIV antigens independently of systemic humoral immunity. In addition, a cytotoxic cervicovaginal immunity against HIV has been shown in some women, suggesting that viral antigens are presented to the immune system in a HLA-I, and therefore that HIV antigens were able to cross the mucosal barrier. A second hypothesis, which does not exclude the first, is that an immune response can be induced by repeated deposition of viral antigens on the cervicovaginal mucosa. It has been shown in HEPS women (Highly sexually exposed to HIV-1 persistently IgG seronegative purpose) the existence of IgA antibodies directed against gp41 can inhibit both the transcytosis of the virus through a monolayer epithelial cells and to neutralize the infection of CD4 T cells in vitro.