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Studies: Long-Lasting Drug Prevents HIV Infection in Monkeys, Implications for Humans

  • Jessica Berman

In what’s being hailed as a breakthrough in HIV prevention, researchers have developed a slow-release version of an antiretroviral medication that offers long-lasting protection against the AIDS virus.

Injections of long-lasting AIDS drugs protected monkeys against infection for weeks, and researchers hope that it could lead to an important step forward in preventing the disease in humans.

In experiments with rhesus macaques, researchers at the Aaron Diamond AIDS Research Center in New York gave two injections of the slow-release drug to eight monkeys. The animals were protected against repeated attempts to infect them with a hybrid human and monkey immunodeficiency virus, called SHIV. Macaques that received a placebo became infected.

Next, investigators wanted to see how long the drug worked. They injected 12 macaques, trying once a week to infect them. On the 10th try, the animals developed SHIV. Because macaques clear the drug from their system more quickly than people do, researchers think it could offer humans protection against HIV for up to three months.

Robert Grant, a virologist at the University of California, San Francisco, led trials of so-called pre-exposure prophylaxis or PreP using the anti-AIDS pill Truvada.

The study showed the procedure was effective if people took the oral medication daily. Many do not, so Grant said oral PreP does not work for everyone who is at risk.

He thinks an injectable drug that provides three months' protection against the virus is a breakthrough.

“This is a very exciting approach, especially for people who have had difficulty taking pills in the past. These are younger people who are not taking medications for other reasons and whose daily life is not highly organized in a way that allows them to build a habit of taking a pill a day,” said Grant.

In the United States, young people account for an estimated 40 percent of new HIV infections.

The drug, called dolutegravir, is already being used by thousands of HIV-positive individuals. Researchers say it is safe. In its injectable form, dolutegravir is embedded in nanoparticles that slowly release the drug over a long period of time.

Large scale clinical trials are already being planned. Experts say the injectable drug would be of great benefit in countries with high HIV rates and where adherence to daily oral prophylaxis is poor.