can oral sex make you hiv-immune?

from hivplusmag.com
origianal source here

A study published online in advance of release in the print journal AIDS shows that oral sex may actually help prevent HIV infection in sexually active gay men.

Researchers in Sweden studied several gay male couples in which one partner is HIV-positive but not taking anti-HIV medications and the other partner is HIV-negative. They found that many of the HIV-negative men who were repeatedly exposed to HIV through the semen or preseminal fluids of their HIV-positive partners during oral sex developed an antibody response in their saliva that neutralized the virus.

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The researchers believe that repeated exposure to HIV during oral sex leads to the production of the antibody IgA1 in the saliva, which has been shown in previous studies to have an anti-HIV effect. Of the 25 HIV-negative men studied, 15 developed antibody responses that completed neutralized HIV in lab tests. Some of the remaining 10 men developed partial antibody responses to the virus.

When the IgA1 antibody was removed from the 15 samples that showed complete resistance to HIV, two thirds were no longer able to neutralize the virus.

Two years after the initial study, new saliva samples were taken and tested. Fourteen of the 15 men who had developed antibody resistance to HIV retained that resistance, and one of the 10 men with partial resistance developed a more robust antibody response, the researchers say. All of the HIV-negative study subjects remained uninfected.

The researchers say that their findings could help to explain why oral transmissions of HIV are rare, even among sero- discordant couples who regularly practice unprotected oral sex. They also say their research backs up the findings of previous studies showing that female sex workers in Kenya who were repeatedly exposed to HIV but never became infected had gradually built up antibody defenses against the virus over time.