Researchers at UT Southwestern Medical Centre have found that prescription drugs now used to treat human immunodeficiency virus infection in adults may prevent the vaginal transmission of HIV.
The study found that anti-retroviral drugs given daily before and after exposure to HIV could prevent vaginal transmission of the virus that causes AIDS.
For the study, the researchers used a highly sophisticated human/mouse chimera or 'humanized mouse,' that have fully developed human immune systems and produce the infection-fighting cells that are specifically targeted by HIV in humans.
It was found that almost 90 percent of the humanized mice inoculated vaginally with HIV became infected with the virus, on contrary, none of the humanized mice given the anti-retroviral drugs emtricitabine (FTC) and tenofovir disoproxil fumarate (TDF) displayed any evidence of infection.
"Our observations support the potential for antiviral drugs to function as an effective pre-exposure prophylaxis against the further spread of AIDS," said Dr. J. Victor Garcia-Martinez, professor of internal medicine at UT Southwestern and the study's senior author.
However, he said that one potential caveat is that the tests were conducted on humanized mice and not humans.
"This is a human/mouse chimeric model that clearly recapitulates very important aspects of humans, but at the end of the day, these are mice. It will take additional work to translate these observations to humans," he said.
In the study, the mice were given the anti-retroviral drugs once a day for seven consecutive days starting 48 hours before being challenged intravaginally with HIV.
The researchers found that none of the mice that had been given the anti-retroviral drugs contracted HIV; however, seven of the eight mice that didn't receive the anti-retroviral drugs tested positive for the infection as early as two weeks post-infection.
Dr. Garcia said that if this pattern proves to be true in subsequent trials, women someday might have to take one pill a day in order to potentially prevent vaginal transmission of HIV.
"One important issue to keep in mind is that pre-exposure prophylaxis is not something that would be advantageous or cost-effective to use in areas where there's a very low incidence of HIV infection," he said.
"If you take this pill on a regular basis, but you're not exposed to this virus, then the drugs are not doing any good and could potentially do harm. But, in parts of the world where the likelihood of exposure is significantly higher, the risk of contracting HIV may warrant taking these medications," he added.
Dr. Garcia said that the study however suggest that existing anti-retroviral drugs can help curtail the spread of the HIV/AIDS epidemic.
The study is appearing online in PLoS Medicine.