Main Category: Sexual Health / STDs
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Anti-HIV drug, tenofovir, when formulated as a vaginal gel, was found to reduce herpes simplex risk in females, researchers from the USA, Belgium and Italy reported in the journal Cell Host & Microbe. The scientists explained that this is because of the higher concentrations that reach vaginal cells in the vaginal gel formulation, compared to the drug when taken orally.
The authors explained that tenofovir disables a DNA enzyme of the herpes virus - reverse transcriptase - thus stopping its spread.
This study was a collaboration between researchers from the Catholic University of Leuven (Belgium), the University of Rome (Italy), the National Institute of Child Health and Human Development (NICHD) (USA), and Gilead Sciences Inc.
A 2010 clinical trial found that tenofovir in vaginal gel form reduced the risk of HSV (herpes simplex virus) infections, as well as HIV infections in females. In this latest report, scientists say they can explain why.
Oral Tenofovir had been shown to undermine the reproduction of HIV. However, nobody knew it could block the genital herpes virus.
Leonid Margolis, Ph.D., NICHD, said:
"HIV infection is closely associated with herpes viral infection. When people with genital herpes are exposed to HIV, they are more likely to become infected than are people who do not carry the herpes virus. Human tissues convert tenofovir to a form that suppresses HIV. We found that this form of tenofovir also suppresses HSV. This discovery may help to identify drugs to treat the two viruses even more effectively."
Dr. Margolis explained that previously approved drugs which are found to have other therapeutic benefits, apart from those they were approved for, can save millions of dollars. A new compound has to undergo extensive testing for efficacy and safety before eventually coming onto the market several years and millions of dollars later. In the case of an already existing drug, most of the safety and other testing has already been done.
The scientist studied individual cells and groups of cells that had been infected with HSV. They found that tenofovir, in high concentrations blocked the virus' ability to reproduce.
Their study also showed that tenofovir does not damage cells, such as those that line the vagina. Vaginal cells are targeted by HIV and HSV.
Cellular enzymes convert tenofovir into another chemical form which suppresses both HIV and HSV. The new chemical form deactivates an enzyme that is crucial for the virus' reproduction.
They tested tenofovir in tissue samples, including tonsils and cervix. After 12 days they found that tenofovir-treated samples only had from 1% to 13% of viral levels compared to untreated samples. They also found that tenofovir blocked viral reproduction of both HIV and HSV simultaneously in infected tissue.
In laboratory experiments, they found that mice infected with the herpes virus had no herpes symptoms and lived longer when treated with tenofovir.
When tenofovir is taken orally, concentration levels in target cells are not high enough to affect HSV in any significant way, the authors explained.
Dr. Morgolis said:
"When using the gel, the amount of tenofovir on the affected tissues is about 100 times the amount in the body when taking tenofovir in pill form. That explains why its anti-herpes activity wasn't noticed before. Thus, under proper conditions, an anti-HIV drug becomes an anti-HSV drug."
Written by Christian Nordqvist
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today
Graciela Andrei, Robert Snoeck, and Jan Balzarini (senior author), Joost van den Oord, Catholic University of Leuven; Emanuela Balestra, Carlo-Federico Perno (senior author), University of Rome; Tomas Cihlar, Gilead Sciences; and Andrea Lisco, Christophe Vanpouille, Andrea Introini, and Leonid Margolis (senior author) NICHD.
Cell Host & Microbe, Volume 10, Issue 4, 379-389, 20 October 2011 (10.1016/j.chom.2011.08.015) Please use one of the following formats to cite this article in your essay, paper or report:
MLA
30 Oct. 2011.
Please note: If no author information is provided, the source is cited instead.
posted by Sammy on 25 Oct 2011 at 9:51 pm
Women with herpes are unlucky to have herpes because it brings much trouble to their life; they are lucky at the same time because the virus will make them have less chance to have breast cancer.
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