A potent new drug derived from bananas may open the door to new ways to prevent sexual transmission of HIV. Scientists have found that lectins - a set of naturally occurring chemicals in plants - can halt the chain of reaction that leads to a variety of infections.

In lab tests, BanLec, the lectin found in bananas, was found to be as potent as two current anti-HIV drugs. It may become a less expensive new component of applied vaginal microbicides, according to new findings published in the Journal of Biological Chemistry . Scientists have been looking for new ways of stopping the spread of HIV. The rate of new infections is outpacing the rate of new individuals getting anti-retroviral drugs, scientists said. It appears an effective vaccine could still be years away.

Although condom use is effective, they are most successful in preventing infection if used consistently and correctly, which is often not the case. "In settings where women have limited control over sexual matters, a long lasting, self-applied microbicide can be very attractive," said David Marvovitz of the University of Michigan Medical School and lead author of the paper.

Some of the most promising compounds for inhibiting vaginal and rectal HIV transmission are agents that block HIV prior to integration into its target cell.

The new research describes the complex actions of lectins and their ability to outsmart HIV. Lectins are sugar- binding proteins and can identify foreign invaders, like a virus, and attach themselves to the pathogen, thus blocking its entry into the human body. The team has developed a way to isolate BanLec from bananas.