Scientists at the University of Waterloo have developed a promising new medical device that could help protect women from HIV. The technology consists of a vaginal implant that basically reduces the amount of targets the virus can latch onto during sex, and may prove a more effective measure than some anti-HIV drugs or condoms in fending off infections.

The new tool takes aim at a mechanism by which HIV can be transmitted between humans. The virus infiltrates a subject by corrupting their all-important T cells, which kick into gear when they catch wind of a foreign invader. If the T cells lay dormant and don't take up the fight, then the virus is unable to infect them and is not transmitted. This is known as immune quiescence.

The starting point for the University of Waterloo scientists was earlier research on HIV infection among Kenyan sex workers. Emmanuel Ho, a professor in the School of Pharmacy at Waterloo, and his partner had found that many female Kenyan sex workers had not contracted the virus, despite having relations with HIV positive clients. The scientists found natural immune quiescence to be the reason.

"Observing this, we asked ourselves if it was possible to pharmacologically induce immune quiescence with medication that was better assured of reaching the point of infection," says Ho. "By delivering the medication exactly where it's needed, we hoped to increase the chances of inducing immune quiescence."

Ho and his team went about this by developing a vaginal implant consisting of a hollow tube and a pair of pliable arms. The arms hold it in place while hydroxychloroquine, a malaria medication also shown to calm immune activation, is delivered and slowly absorbed by the walls of the vaginal tract.

The implant was tested in animal models where it induced a significant reduction in T cell activation. Armed with these positive early results, the researchers are now working to improve the approach and find out where it fits in among other HIV prevention measures.

"We know that some drugs taken orally never make it to the vaginal tract, so this implant could provide a more reliable way to encourage T cells not to respond to infection and therefore more reliably and cheaply prevent transmission," says Ho. "What we don't know yet is if this can be a stand-alone option for preventing HIV transmission or if it might be best used in conjunction with other prevention strategies. We aim to answer these questions with future research."

The research was published in the Journal of Controlled Release.

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