January 16, 2008
Antiretroviral drugs might be effective at preventing the vaginal transmission of HIV, according to a study published in the Jan. 14 issue of PLoS Medicine, the Austin American-Statesman reports. For the study, Victor Garcia-Martinez, professor of internal medicine at the University of Texas-Southwestern, and colleagues engineered mice with human stem cell transplants so the mice's bodies would mimic how a human immune system would react to HIV (Roser, Austin American-Statesman, 1/15).
Researchers then gave the mice daily doses of the antiretroviral drugs emtricitabine and tenofovir disoproxil fumarate for seven consecutive days, starting 48 hours before intravaginal exposure to HIV, the ANI/New Kerala reports. The study showed that nearly 90% of the mice that did not receive antiretrovirals contracted the virus, but none of the mice that received antiretroviral treatment tested HIV-positive, ANI/New Kerala reports.
"Our observations support the potential for [antiretroviral drugs] to function as an effective pre-exposure prophylaxis against further spread of AIDS," Garcia-Martinez said. However, he added that the humanized mouse model "clearly recapitulates very important aspects of humans, but at the end of the day, these are mice. It will take additional work to translate observations to humans" (ANI/New Kerala, 1/15).
Human clinical trials under way in Africa, Thailand and the U.S. are testing Garcia-Martinez's concept and could "propel the research ahead," the American-Statesman reports. Garcia-Martinez said he expects trial results in three years. He added that Africa would stand to benefit the most if the research proves effective but that PrEP campaigns would require major funding. Antiretrovirals cost about $3,500 or more annually and can cause side effects, David Wright, principal investigator of AIDS research at Central Texas Clinical Research, said, adding that developing countries do not have "enough money to buy" the drugs even for those who are living with the disease. Wright also raised the concern that people taking antiretrovirals as a method of PrEP might forgo using condoms.
Garcia-Martinez said his team did not analyze either issue. "We proved that transmission via the vaginal tract can be prevented. We can't control what free people are going to do," he said (Austin American-Statesman, 1/15). He added, "Our motivation is to look for interventions that can be implemented rapidly and have the potential to make a big difference. We don't want something in 10 years. We want female-controlled prevention measures now" (HealthDay/Yahoo News!, 1/15). Rowena Johnston, vice president for research at the American Foundation for AIDS Research, said, "The principle of this paper is a very important one. We need different ways of attack" (Austin American-Statesman, 1/15).
The study is available online.
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