AIDS-preventing gel to protect women in resource-poor areas

22:57 August 16, 2009 PDT

University of Utah bioengineer Patrick Kiser analyzes polymers used to develop a new kind of AIDS-preventing vaginal gel for eventual use by women in Africa and other impoverished areas (Photo: University of Utah)

The statistics paint a grim picture - an estimated 2.0 million people, including 270,000 children, died of AIDS in 2007 and at that time 33 million people around the globe were living with HIV, two thirds of them in sub-Saharan Africa. New advancements in microbicides may help to improve this horrific scenario with U.S. researchers undertaking trials for a specially designed ‘molecular condom’ to prevent the spread of HIV in women.

Developed by the University of Utah’s College of Engineering, the ‘molecular condom’ takes the form of a vaginal gel that becomes semi-solid.

In order to eradicate the potential for infection, particularly among women whose cultural or socioeconomic conditions render them unable to access protection against the virus, the crucial function of the unique gel is to keep HIV-infected seminal fluid from interacting with vaginal tissue.

According to Patrick Kiser, an associate professor of bioengineering at the University's College of Engineering, technology in microbicides is important because it "can enable women to protect themselves against HIV…particularly in resource-poor areas of the world like sub-Sahara Africa and south Asia where…women are often not empowered to force their partners to wear a condom."

The gel is made of two polymers, molecular units called PBA (phenylboronic acid) and SHA (salicylhydroxamic acid). When the gel is inserted into the vagina, a normally acidic pH environment, these polymers attach and detach allowing the gel to flow. During intercourse, the presence of semen alters the pH levels, creating a more alkaline vaginal environment and causing the polymers to bond tightly together, forming a semisolid mesh of cross-linked molecules.

It is in the presence of these cross-linked molecules—their mesh size recorded at 30 – 50 nanometers in width compared to an HIV particle of 100 nanometers in width—that the virus becomes trapped and effectively blocked from interacting with vaginal tissue.

When the vagina returns to its normal pH, residual HIV particles are inactivated by the environment’s acidity but, to avoid running the risk of immune cells becoming infected in their attack on HIV, Kiser also intends to incorporate an anti-viral drug such as tenofovir into the gel as an additional safeguard for these cells.

A study testing the behavior of the new gel and showing how it traps AIDS-causing HIV particles is published in the journal Advanced Functional Materials.