Human immunodeficiency virus-1 specific and natural cellular immunity in HIV seronegative subjects with multiple sexual exposures to virus

The probability of HIV infection by sexual contact, although it varies grea tly, appears to be lower than that of infection by other routes of exposure . The aim of this study was to evaluate immunological determinants involved in protection against HIV infection in subjects with multiple and repeated sexual exposures to the virus. Twenty-two subjects were studied for CD8+ c ell anti-HIV suppression activity and serum neutralizing activity against t he HIV strain of their own partners, beta -chemokine production, and natura l killer cell activity. CD8+ cell anti-HIV activity and neutralizing activi ty of sera were found in 13 (76%) and 12 (70.5%) out of 17 HIV-1 negative s ubjects, respectively. Six individuals had a relevant immune response again st HIV: three subjects with a high CD8+ cell antiviral suppression activity and three individuals with sera neutralizing activity titer >1:10. These l ast three subjects had the highest beta -chemokine levels, a very prolonged period of multiple sexual intercourse (>6 years) and a seropositive partne r with a high viral load. A partial reduction of neutralizing activity tite r was observed when preincubating the sera with anti-beta -chemokine neutra lizing antibodies. A spontaneous natural killer cell activity was suppresse d in the majority of HIV-1 negative subjects with sexual exposure in compar ison with normal individuals. The protection from sexual HIV transmission a ppears to be the result of a network of different humoral and cellular fact ors. J. Mad. Virol. 64:232-237. 2001. (C) 2001 Wiley-Liss, Inc.