Double Trouble: Vaginal Gel Protects Against HIV and HSV Replication

Since we have spent a significant amount of time this week discussing viral modes of transmission and the molecular biology behind it, I find it suiting to discuss a new study that was recently published in the Cell Host and Microbe journal and covered by the New York Times entitled “Topical Tenofovir, a Microbicide Effective Against HIV, Inhibits Herpes Simplex Virus-2 Replication.” A longitudinal study conducted by Caprisa (Durban-based AIDS research center) involving 889 women showed a positive correlation between the use of a vaginal gel- Tenofovir- and a reduction in the probability of infection. Women who used this vaginal gel were 54 percent less likely to acquire an HIV infection. Surprisingly, the benefits of the gel did not stop there. It was also shown that these women had a protection rate against herpes-simplex virus 2 of 62 percent.
These benefits though are only effective against herpes when tenofovir is taken as a vaginal gel and not when it is ingested in the form of a pill. As a gel, the active tenofovir metabolite directly inhibits the herpes simplex virus DNA polymerase, thus inhibiting its ability to replicate. Not to mention, the tissue concentrations of the drug are approximately 100 times higher in the gel than in its pill counterpart.
The benefits of this gel are more than physiological, there are also behavioral and economical factors that weigh into the pros. Financially, this product as a combination of an anti-HIV and anti-herpes drug increases its targeted population, especially in the United States where almost 21 percent of sexually active women are infected with the herpes simplex virus. In regards to behavioral benefits of this form, since the use of the vaginal gel is controlled by the woman herself, she can ensure a level of protection from infection by sexual transmission that is not offered by certain forms of contraception. Further studies need to be conducted in order to test the reliability of the gel as well as its effectiveness if used on a daily basis rather than being used prior to and following sexual intercourse.

Resources:
McNeil, Donald G "Gel Cuts Women's Risk of Herpes, Study Finds"

Andrei, Graciela et al. "Topical Tenofovir, a Microbicide Effective against HIV, Inhibits Herpes Simplex Virus-2 Replication." Cell Host and Microbe. Vol 10,4. October 1011. pp379-389

-Angela Ceseña