Semen Protects HIV from Microbicide Attack
Microbicides that kill HIV in the lab often fail in clinical trials. A study finds that semen may be the culprit. Cynthia Graber reports
By Cynthia Graber
SUBSCRIBE TO Science Quickly
On supporting science journalism
If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
They were thought to have great promise in the fight to stop the spread of AIDS. Indeed, vaginal microbicides did a fine job killing HIV in the lab. But they failed to work in clinical trials.
Now, researchers think they have identified the culprit: semen.
In previous studies, scientists had looked at the HIV virus on cells protected by microbicides. But the latest tests evaluated microbicides in the more real-world situation where semen is present. And semen stopped the microbicides from working. Probably because semen contains protein fragments that help HIV to attach to cell surfaces and infect cells.
The research is in the journal Science Translational Medicine. [Onofrio Zirafi et al, Semen enhances HIV infectivity and impairs the antiviral efficacy of microbicides]
There’s good news, though—a drug not currently used as a microbicide did seem to offer protection. It’s an antiretroviral called Maraviroc. Conventional microbicides target the virus itself. But Maraviroc binds to receptors on host cells. That action forms a barrier that prevents the HIV from attaching to the cell. Maraviroc is currently approved as an HIV drug, and is being considered as a microbicide to try to stop infection in the first place.
The research is a reminder that, in drug testing, context is crucial.
—Cynthia Graber
[The above text is a transcript of this podcast.]
Subscribe to Support Independent Journalism
Great science journalism requires human expertise, time, effort and creativity. And it costs money. That’s why I and the journalists here at Scientific American hope you’ll join our community.
When you subscribe, you are supporting staff and freelance journalists who are passionate about telling science stories that are true, important and compelling. Our editors and reporters are often experts in their fields, which means they understand the nuances of big discoveries and can untangle the breakthroughs from the hype. With a subscription, you are also supporting rigorous fact-checking to ensure the words we publish are precise and accurate. And you’re supporting original illustrations, graphics and photos that bring you closer to an advanced laboratory, an ice sheet in Antarctica or a space mission in orbit. You’re helping us craft other types of high-quality journalism as well: Our newsletters are carefully written, edited and curated by staffers you have or will come to know and love. Our Science Quickly podcast is based on original reporting, collaboration with editors and scientists and exacting production.
Subscriptions keep this engine running so we can continue to deliver thoughtful, rigorous and independent science journalism to you. In an era of viral misinformation, this work is crucial. If you value what we do, I hope you’ll consider joining us as a subscriber
