A new animal study published in PLoS Medicine suggests that the antiretroviral drugs used to treat HIV could also protect people from getting the AIDS virus. Although HIV treatment has rapidly advanced since the introduction of antiretroviral drugs in the 1990s, the absence of an effective vaccine means the virus continues to spread. Pre-exposure prophylaxis (PrEP) - the prevention of infection by treating people with drugs before they are exposed - is often used to prevent malaria, but has not yet been shown to be effective against sexual transmission of HIV.
The study found that those macaque monkeys which were repeatedly exposed to SHIV (a virus closely related to HIV) but received antiretroviral drugs were less likely to become infected than exposed macaques that received no anti-HIV medication. The best protection was seen in macaques that had received a combination of two drugs.
To simulate a common route of HIV transmission in humans, the researchers exposed the macaques to low weekly doses of SHIV that were given rectally. The anti-HIV drugs tested were emtricitabine (FTC), tenofovir and both drugs combined.
The results showed that the macaques who received drugs were less likely to become infected than those in the control group. Impressively, all of the macaques receiving the combination of both FTC and the high dosage of tenofovir were protected from infection - whether they were from the group that received these drugs daily, or only around the time of exposure to infection. The results suggest that higher doses and combinations of drugs worked better than single or low doses, and also that PrEP may not need to be administered every day to be effective.
The researchers also found some viral resistance to one of the drugs, FTC, in macaques that became infected. In addition, doses of tenofovir that resulted in maximum protection for macaques are higher than would be safe in humans. Nevertheless, the results "highlight an exciting and potentially important use" of antiretroviral drugs to prevent sexual transmission of HIV, noted the journal.
Related:
AIDS/HIV - Treatment Research
Source: Public Library of Science
