The Bay Area Reporter - March 1, 1999
Don Howard, ACT UP/Golden Gate Writers Pool

Virus levels, infectiousness link

Several studies have found that higher viral load probably makes people more infectious:

* Studies from early in the epidemic found that having unprotected sex with HIV-positive people with AIDS is more likely to result in HIV infection than having sex with asymptomatic HIV-positive people. Because people with AIDS typically have higher virus levels in their blood than asymptomatic HIV-positive people, researchers have concluded that people with higher virus levels are more infectious.

* Studies have also shown that pregnant mothers with high virus levels are more likely to transmit HIV to their babies before, during, or after delivery.

* A 1997 study of people infected from blood transfusions (Mosley, American Journal of Epidemiology) showed that study participants who transmitted HIV to their sexual partners had higher virus levels than did non-transmitting patients.

Anti-HIV therapies reduce virus levels in semen

Anti-HIV therapies that reduce virus levels in blood can also reduce virus levels in semen:

* A study published in AIDS in August of 1997 (Eron) showed that, in a group of 44 patients who started anti-HIV therapy, treatment resulted in a significant fall in the virus levels in semen that paralleled the reduction of virus levels in blood. More pronounced reductions of HIV (RNA) in semen were observed as the effectiveness of treatment on blood HIV levels increased. Thirteen patients had undetectable HIV levels in blood on treatment and all of these also had undetectable levels of HIV in semen by culture and RNA analysis. In 19 of the 31 patients (62 percent) who still had HIV in their blood during treatment, semen HIV levels were below detection at follow-up. This group of researchers concluded that, "treatment-induced changes of HIV concentration in blood are generally associated with a corresponding change in seminal HIV" and that "potent antiretroviral therapy might reduce the spread of HIV."

* A 1997 study conducted at the University of North Carolina Chapel Hill (Gilliam) showed that treating HIV infected men with anti-HIV medications cut the amount of virus in semen by about 90 percent.

* In a study published in August of 1997 in the Journal of Virology (Rinaldo), researchers reported that virus levels in semen and blood decreased markedly in six patients on combination anti-HIV therapy.

* The controversial, but important, AIDS Clinical Trials Group Study 076 showed that anti-HIV drug treatment of HIV-positive mothers before and during delivery dramatically reduced the transmission of HIV to their children (along with drug therapy in the newborn after delivery). These findings have been rapidly introduced into clinical practice and have led to profound reductions in the number of children born with HIV.

Lower viral load in semen doesn't mean you can't infect someone

Even if anti-HIV therapy reduces viral load in semen, researchers have proved that the risk of infecting someone still exists:

* A study published last month in the New England Journal of Medicine (Pomerantz) showed that HIV-infected cells and replication-competent virus particles could still be found in the semen of men with undetectable viral loads in their blood. In this study, researchers collected blood and semen samples from seven men with HIV infection who were on anti-HIV therapy and who had no detectable virus (RNA below 50 copies per milliliter) in blood. The researchers analyzed semen samples from the seven men and, despite the long-term suppression of HIV in their blood, infected cells harboring HIV DNA were detected in four subjects. (These infected cells could become activated in someone else's body and cause infection.) The researchers also found virus particles (RNA) in the semen cells of two of the men.

* This same researchers found that the viruses recovered from the semen cells of these patients had no mutations suggestive of resistance to anti-HIV drugs and were macrophage-tropic, a feature that is characteristic of HIV strains that are capable of being sexually transmitted. The researchers concluded that, "in HIV-infected men who are receiving highly active antiretroviral therapy and who have no detectable levels of HIV in blood, the virus may be present in semen cells and therefore may be capable of being transmitted sexually."

* Another study, conducted by researchers at Harvard and published in 1998 (Byrn), showed that HIV in semen arises from a genetically distinct virus reservoir - perhaps one which is not accessible to anti-HIV drugs. By demonstrating the difference in the ratio of uninfected cells to infected cells in blood and semen they concluded that the sources of infection were different. In addition, infectious HIV was isolated from semen cells, but not from blood cells, of a man on triple combination therapy. The researchers noted the absence of major resistance mutations in the semen virus, indicating that it was replicating in isolation from the patient's drug therapy. The researchers concluded that "there is a distinct compartmentalization of HIV in the semen of this study cohort" and that their findings "support the concept that semen HIV arises from an isolated reservoir of infection."

Keep using condoms

It may be attractive to think that lower viral load means you are not infectious. But, the studies above show that, while you may indeed by less infectious, the risk of infecting someone is not zero. Dr. Jeff Martin from the University of California San Francisco's Center for AIDS Prevention Studies (CAPS) says, "from a theoretical viewpoint, it is quite likely that the new drugs lower one's infectivity by the reducing the amount of virus in semen but whether this goes to zero is unknown. The smart bet is that it doesn't go to zero chance of infecting another person."

And there's another complication - if you do end up infecting someone, it could be with drug-resistant virus. Recent studies have documented that drug resistant HIV can be transmitted to your partner if you fail therapy. And the results can be catastrophic, warns Project Inform's Brenda Lein. "When someone is infected with drug resistant HIV, the likelihood of that individual benefiting from current anti-HIV approaches diminishes leaving them, perhaps, in the same situation people were in during the 1980s, with little or no therapy options."

990301
BR990301

Always watch for outdated information. This article first appeared in 1999. This material is designed to support, not replace, the relationship that exists between you and your doctor.

AEGiS presents published material, reprinted with permission and neither endorses nor opposes any material. All information contained on this website, including information relating to health conditions, products, and treatments, is for informational purposes only. It is often presented in summary or aggregate form. It is not meant to be a substitute for the advice provided by your own physician or other medical professionals. Always discuss treatment options with a doctor who specializes in treating HIV.

Copyright ©1980, 1999. AEGiS. All materials appearing on AEGiS are protected by copyright as a collective work or compilation under U.S. copyright and other laws and are the property of AEGiS, or the party credited as the provider of the content. .