Nav: Home

Antiretroviral drugs are not foolproof in preventing sexual transmission of HIV, says Pittsburgh-Rio de Janeiro study

August 14, 2000

Antiretroviral therapy for HIV patients can be a double-edged sword, according to University of Pittsburgh AIDS researchers and their Brazilian colleagues. Investigators showed that while the drugs can greatly reduce the amount of infectious HIV in semen (viral load), a substantial percentage of men may still be able to transmit the virus sexually. This is the first-ever study to simulate a clinical environment in looking at the effects of antiretroviral drugs on HIV concentration in semen.

The findings, made by researchers at the University of Pittsburgh Graduate School of Public Health (GSPH) and School of Medicine, and the Universidade Federal do Rio de Janeiro (Brazil), are published in the August 15 issue of the Annals of Internal Medicine.

"Our study is the first to show that, in a real-world setting, a substantial percentage of HIV-positive men have active, potentially infectious virus in their semen, even after six months of therapy," said Lee Harrison, M.D., associate professor of medicine and epidemiology, director of the Public Health Infections Diseases Lab at the University of Pittsburgh and senior author of the study.

Previous small, short-term studies have suggested that antiretroviral therapy reduces, but not completely eliminates, seminal viral load in HIV-infected men. But, because these earlier studies were not definitive for a number of reasons, scientists remained unsure whether the findings would translate into a larger community setting. The Pittsburgh-Rio de Janeiro study provides a clearer picture of just how resilient -- and potentially transmittable -- the AIDS virus is during therapy.

"Certainly, current drug regimens have been shown to reduce the likelihood of sexual transmission of HIV, and our study has provided additional evidence that these regimens are effective in reducing viral load in both the blood and semen of many men in our study," commented Paulo Barroso, M.D., Ph.D., assistant professor and head, Infectious Diseases Service, School of Medicine, Universidade Federal do Rio de Janeiro. "Nonetheless, a significant proportion of men who underwent therapy and subsequently felt well remained potentially infectious and therefore continue to pose a public health risk unless they monitor their sexual behavior carefully."

The study was conducted at the Hospital Universitário Clementino Fraga Filho in Rio de Janeiro from November 1996 through May 1998. Ninety-three HIV-infected male volunteers agreed to undergo antiretroviral therapy, with the decision to start, change or stop therapy left up to the volunteers and their personal physicians, thus simulating a clinical environment. All but two of the subjects were antiretroviral-naïve (had never been on antiretroviral therapy).

Eighty of the study subjects began with a double nucleoside reverse transcriptase inhibitor (NRTI) drug regimen. The best known NRTI is zidovudine (Retrovir), formerly known as AZT. NRTIs prevent the integration of HIV genes into the host cell's genome. Another type of drug, known as a protease inhibitor, was added to the regimen for 13 of the subjects. Protease inhibitors block the release of mature, infectious HIV particles from HIV-infected immune cells. By the end of the study, 19 subjects were using the triple-drug program, having changed drug regimens upon the advice of their own physicians.

After six months of therapy, there was a 66 percent reduction in the number of study subjects with detectable seminal HIV viral load. Of the 64 subjects who had detectable HIV in their semen before initiating therapy, 44 had undetectable levels after six months. Also, those volunteers who used the double nucleoside had a statistically significant reduction in seminal HIV viral load as measured at all follow-up visits one, two, three and six months after initiation of therapy.

"In spite of these impressive treatment outcomes, a third of the treated men had infectious virus in their semen after six months, including 13 percent of patients who were taking a protease-inhibitor-containing triple-drug regimen" said Dr. Barroso. "Thus, because there is no guarantee that HIV-infected individuals will not be infectious themselves, they should continue to practice safe sex and follow medication instructions to the letter."

In a landmark study conducted previously at the University of Pittsburgh's GSPH, investigators found infectious HIV in the semen of a small group of men who had received antiretroviral therapy and who were in various stages of disease. More recent work has shown that, even after HIV-infected patients underwent antiretroviral therapy, so-called HIV "provirus" remained integrated within the genome of cells in semen. Whether these patients are infectious or not, however, is not known.

"In general, it's safe to say that men who have a detectable viral load after six months on therapy have a high likelihood of carrying - and possibly sexually transmitting - infectious HIV," said Dr. Harrison. "We suspect that the seminal HIV in these men is drug resistant, although definitive studies examining this issue are still ongoing."

A further concern, according to Drs. Harrison and Barroso, is that treated men do not become complacent because they are on aggressive therapy. This study confirms the finding that infectious HIV may still lurk within their semen.
-end-
Lauren Ward
FAX: 412-624-3184
E-MAIL:
wardle@msx.upmc.edu

University of Pittsburgh Medical Center

Related Hiv Articles:

The Lancet HIV: Severe anti-LGBT legislations associated with lower testing and awareness of HIV in African countries
This first systematic review to investigate HIV testing, treatment and viral suppression in men who have sex with men in Africa finds that among the most recent studies (conducted after 2011) only half of men have been tested for HIV in the past 12 months.
The Lancet HIV: Tenfold increase in number of adolescents on HIV treatment in South Africa since 2010, but many still untreated
A new study of more than 700,000 one to 19-year olds being treated for HIV infection suggests a ten-fold increase in the number of adolescents aged 15 to 19 receiving HIV treatment in South Africa, according to results published in The Lancet HIV journal.
Starting HIV treatment in ERs may be key to ending HIV spread worldwide
In a follow-up study conducted in South Africa, Johns Hopkins Medicine researchers say they have evidence that hospital emergency departments (EDs) worldwide may be key strategic settings for curbing the spread of HIV infections in hard-to-reach populations if the EDs jump-start treatment and case management as well as diagnosis of the disease.
NIH HIV experts prioritize research to achieve sustained ART-free HIV remission
Achieving sustained remission of HIV without life-long antiretroviral therapy (ART) is a top HIV research priority, according to a new commentary in JAMA by experts at the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health.
First ever living donor HIV-to-HIV kidney transplant
For the first time, a person living with HIV has donated a kidney to a transplant recipient also living with HIV.
More Hiv News and Hiv Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Erasing The Stigma
Many of us either cope with mental illness or know someone who does. But we still have a hard time talking about it. This hour, TED speakers explore ways to push past — and even erase — the stigma. Guests include musician and comedian Jordan Raskopoulos, neuroscientist and psychiatrist Thomas Insel, psychiatrist Dixon Chibanda, anxiety and depression researcher Olivia Remes, and entrepreneur Sangu Delle.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...