Microbicide design for AIDS prevention

Biomedical engineers have developed a computer tool they say could lead to improvements in topical microbicides being developed for women to use to prevent infection by the virus that causes AIDS, report researchers at Duke University, Durham, N.C. Providing women with improved microbicides is a pressing challenge because females now account for a growing number of new infections worldwide.

Females are about twice as likely as males to contract HIV during vaginal intercourse, according to the Centers for Disease Control and Prevention. In developing countries particularly, cultural and socioeconomic inequities between the sexes also can leave women more susceptible. "In many cases, women lack control over their abilities to protect themselves against the virus," indicates David Katz, professor of biomedical engineering. "Microbicide development is a response to the demonstrated need for new female-controlled methods for HIV prophylaxis"

By applying fundamentals of physics and chemistry, scientists have developed a computer model that can predict the effectiveness of various microbicidal recipes in destroying human immunodeficiency virus (HIV) before it reaches vulnerable body tissues. Using the tool, the researchers have determined that a thin, long-lasting coating of microbicide delivered to susceptible tissues in a woman's vagina significantly can reduce the spread of HIV.

The findings emphasize a critical role for the "delivery vehicle," the various polymer gels or creams that carry the active antimicrobial ingredients, in determining the success or failure of microbicides. Yet, most scientists have concentrated on improving the antimicrobial compounds themselves, rather than their delivery.

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"There is a huge push to produce microbicides that would have any effectiveness at all in reducing the spread of HIV, particularly in places like Africa and Southeast Asia where the disease is rampant," Katz notes. "We are developing methodologies to make the next round of microbicides even better."

"Existing microbicides are excellent in terms of their ability to inactivate HIV," adds Anthony Geonnotti, the study's lead investigator. "Improvements to future generations of microbicides will largely depend on the delivery system and applicators." However, he adds, advances made through continued research on new and better drugs should not be discounted.

In addition to their role in drug delivery, microbicide formulations can act as physical barriers or filters to slow HIV's passage from semen into body tissues, Geonnotti explains. That slowing would give the HIV-neutralizing ingredient in the microbicide layer, as well as the body's natural defenses against HIV, more time to work. If left untreated, HIV attacks a person's immune system and can progress to AIDS.

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COPYRIGHT 2008 Gale, Cengage Learning