Protease inhibitors reduce virus in sperm

With research showing that protease inhibitors can significantly reduce viral load in semen — which may result in decreased infectiousness, as well — health care providers must be alert to a possible downside of these more potent drugs: growing complacence among infected patients in practicing safe sex.

Researchers at Harvard and Brown universities studied 20 HIV-positive men, taking semen samples before treatment, and then one month and six months after treatment. Their findings were presented at the Fourth Conference on Retroviruses and Opportunistic Infections in Washington, DC.1

In general, the amount of virus after treatment was reduced in the patients, but it was not eradicated, says Deborah Anderson, MD, associate professor of obstetrics, gynecology, and reproductive biology at Harvard School of Medicine.

"In four individuals, we continued to see virus even at the six-month point, so it’s a kind of good-news, bad-news result," she says. "We don’t want people to feel that they are no longer infectious just because their blood viremia is down or undetectable."

Because semen is a difficult bodily compartment for drugs to penetrate, the decline in virus doesn’t parallel that found in plasma, she explains. At the same time, the virus that does persist in the face of treatment may be mutated to the point of being resistant to protease inhibitors. The possibility then exists of transmitting a strain that would not respond to the drugs. Anderson is conducting a study to determine whether the remaining virus is resistant.

Even if virus were undetectable in semen, patients must be warned that it is not known how much virus is needed for infectiousness, researchers note. Moreover, unprotected sexual partners are at risk of receiving other sexually transmitted diseases, including hepatitis B, cytomegalovirus, and herpes virus, they add.


1. Boswell S, Mayer K, Goldstein R, et al. The effect of HIV protease inhibitors on seminal proviral DNA. Fourth Conference on Retroviruses and Opportunistic Infections. Abstract # 202.