Practical Prevention of Vaginal and Rectal Transmission of HIV by Adapting the Oral Defense: Use of Commercial Lubricants

HIV is transmitted to 6.4 million people each year, primarily via sex. Condoms, which are highly effective, are recommended as the primary preventive. However, the fact that millions of sexual transmissions occur each year indicates that many people do not use condoms, and additional preventives are thus needed. Hypotonic saliva, which preferentially inhibits HIV production by infected leukocytes by 10,000-fold, appears to contribute to the rarity of oral transmission. The mechanisms of natural prevention of oral transmission by saliva may be adaptable to the susceptible vagina and rectum. The objective of this study was to reduce sexual transmission of HIV by mimicking saliva's targeting of the transmitting infected leukocytes and any cell-free HIV in seminal fluid.

The previously recommended anti-HIV topical microbicide, nonoxynol-9, has not prevented HIV transmission in humans, probably because it causes mucosal irritation and attracts CD4+ cells. To identify an effective but non-irritating preparation, the researchers studied commercial, over-the-counter (OTC) lubricants and vaginal preparations that are in the safest US Food and Drug Administration (FDA) category and do not cause irritation when used repeatedly by large numbers of people. For their study, the researchers purchased 22 OTC topical preparations. The effect of OTC preparations on both the production of HIV by infected leukocytes and cell-free HIV suspended in seminal fluid was measured under simulated in vivo conditions. Researchers excluded preparations with low inhibitory activity and those that were inhibitory but likely to be irritating.

Three OTC products were found to be highly active against both HIV-infected leukocytes suspended in seminal fluid and active against cell-free HIV under in vitro conditions that simulate in vivo conditions. These products were Astroglide vaginal lubricant, Vagisil vaginal moisturizer and ViAmor vaginal moisturizer.

"Overall, these three OTC preparations have desirable properties, which should make them candidates for trials in humans. The attributes of these OTC preparations include being widely available, inexpensive, acceptable, in the safest US FDA category, and usable by recipient women and men. We believe that the World Health Organization, government agencies, and pharmaceutical companies should strongly consider field trials in people at risk," the researchers concluded.

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