When AIDS viruses are transmitted despite treatment

While antiretroviral drugs offer an efficient means of preventing the replication of HIV in the blood, shedding of HIV may occur in semen, so that other persons can become infected during unprotected sexual intercourse. This occurs in particular if the male genital tract also has other viral infections. That is the conclusion reached by a scientist who is supported by the Swiss National Science Foundation (SNSF).

In principle, modern combination therapies are very effective at keeping AIDS causative agents in check. The treatment usually leads to a situation in which there is no longer any evidence of Human-Immunodeficiency Viruses (HIV) in the body. In this way, the drugs can also reduce the disease transmission rate to just one tenth. So why do new infections occur despite treatment?

Sperm containing a cocktail of viruses

The answer, according to findings recently published by the Swiss researcher Sara Gianella Weibel and her American colleagues, is that other viruses also play a role. Working at the University of California in San Diego, the SNSF-funded scientist studied the semen of 114 HIV-infected men undergoing treatment who have sex with men. She found that the seminal fluid of 11 of the men contained a considerable quantity of HI viruses, even though the viral load of the blood of all of the men was very low. In eight of these 11 cases, Gianella Weibel also found evidence of various forms of herpes.

Locally activated immune system

Some of these herpes viruses, such as cytomegalovirus, often remain unnoticed. However, if the viruses infect the male genital tract, they locally activate the immune system. As a result, there is a build-up of immune cells, including those in which HIV replicate, in the genital area. "Our data suggests that we must also direct our focus towards other viruses, if we really want to interrupt the transmission of AIDS," explains Gianella Weibel.