In preliminary laboratory studies, researchers at the University of Texas Medical Branch at Galveston (UTMB) have found what could prove to be a slick new weapon in the battle against AIDS: over-the-counter sexual lubricants. Test-tube experiments show that three "personal lubricants" inhibit HIV production by more than a thousand-fold when mixed with virus-infected seminal fluid, suggesting that use of these substances might greatly reduce the transmission of HIV in locales where condoms are rarely used. Condoms remain the most effective barrier to acquiring AIDS during sexual intercourse, the researchers stress.
Microbiologists Samuel Baron, Joyce Poast, Derrick Nguyen and Miles Cloyd published their discovery July 20 in AIDS Research and Human Retroviruses. It grew out of their earlier work showing that, thanks to its low-salt content, saliva kills HIV-infected white blood cells and helps block oral transmission of the virus.
The investigators knew from previous research that the over-the-counter spermicide nonoxynol-9 could kill infected white blood cells, although studies show that it also may increase HIV transmission by irritating the mucous membranes of the vagina and rectum, causing lesions that offer the AIDS virus a portal into the body. Still, the UTMB researchers wondered whether other over-the-counter substances might offer similar anti-viral effects without causing irritation. So they went to a local drug store and bought a wide variety of products designed for use in the vagina or rectum and then tested them.
These tests narrowed down 22 preparations to just three categorized as safe and effective by the FDA, all three of which killed substantial numbers of infected white blood cells, as well as free HIV, without irritating the tissues. Next, the researchers pitted the chosen substances against HIV-infected cells suspended in seminal fluid.
The results were startling. Mixing the lubricants - sold as Astroglide, Silken Secret, and Vagisil - with HIV infected cells reduced viral output by more than a thousand times. Layering them on top of HIV-infected white blood cells cut virus production by more than thirty times. Moreover, components of the lubricants-currently being identified-deactivated the virus-bearing cells quickly, making a significant impact within five minutes, well short of the 30 minutes required for the infected cells to transmit HIV to the surface cells of the vagina and rectum. The lubricants maintained their effectiveness even when diluted fourfold, and they protected against the virus even after spending eight hours incubating at 98.6 degrees Fahrenheit.
As Baron sees it, the UTMB team's discovery might help reduce HIV transmission in places where condom use is far from routine. Even in the U.S., he points out, only 30 percent of sexually active people use condoms, while in some underdeveloped countries such use falls below 10 percent.
Baron cautions that it's a "big leap from the test tube to the real world." The latter requires a field trial in human beings of the three lubricants, which would cost about $3 million, he says. Baron adds: "No one should use these substances assuming that they will protect you from contracting HIV and from eventually getting AIDS until we have evidence from field trials answering that question." As with any human experimentation, there are also cultural and ethical considerations. But Baron remains excited by the slippery substance's potential. "In countries where you have a 30 percent transmission rate per year," he says, "if you can reduce that by half, you can save a heck of a lot of people."
