Research Reveals How HIV Infects During Sex, May Lead to Better Prevention

Researchers have uncovered the mechanism HIV uses to get past a tight barrier of cells in the female genital tract—and thus cause HIV infection—according to a release by McMaster University in Canada. The study, which could help scientists develop a more effective microbicide or vaccine to prevent HIV, was published April 8 in the online journal PLoS Pathogens.

Up to 90 percent of all HIV infections worldwide are caused by sexual contact. Specifically, to enter the body during intercourse, HIV must get through the epithelium, a lining of tightly meshed cells covering mucosal tissue in the female genital tract and the rectum.

Until now, however, researchers have not understood how HIV gets past these cells. Some have theorized that many infections might be due to small tears in the mucosal lining, while others have suggested that inflammation of immune cells just beneath epithelial cells could cause the epithelium to become permeable.

To explore this further, Charu Kaushic, PhD, from McMaster University in Hamilton, Ontario and her colleagues exposed vaginal and intestinal cells to HIV. According to her group’s research, a protein on HIV’s surface can cause epithelial cells to break. When this happens, the cells become hyperactive and releases destructive inflammatory proteins.

These inflammatory proteins, Kaushic’s group shows, can then neutralize the small electrically charged proteins that keep epithelial cells packed snuggly together, like mortar between bricks. “What it does is make the electrical barrier resistance of epithelial cells decrease. By doing that, the virus can cross the barrier,” Kaushic explained.

Though Kaushic and her colleagues conducted their experiments with vaginal epithelial cells, it is possible that the same mechanism takes place in the rectum. Researchers will have to pursue both lines of research as they move toward developing a microbicide or vaccine that prevents infection at the mucosal level.

“This is a significant step forward in defining where prevention strategies, such as microbicides and vaccine, need to focus,” Kaushic concluded. “Instead of trying to stop HIV from infecting the target cells underneath the epithelium, we need to think about ways to stop the virus from attaching to epithelial cells themselves.”

The Friends of AIDS Foundation is dedicated to leading efforts to combat this disease and create an impact on policy making that will help change the future course of this pandemic. To learn more about The Friends of AIDS Foundation, please visit: http://www.friendsofaids.org.


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