HIV Drug Helps Block Herpes Virus
A recent discovery by NIH researchers has shown the mechanism by which an anti-HIV drug can stop the spread of the virus that causes genital herpes. Tenofovir, when applied as a vaginal gel, damages a key enzyme in the herpes virus, short-circuiting its ability to replicate.1
A study released last year by the Centre for the AIDS Programme of Research in South Africa (CAPRISA) showed that the tenofovir gel — an antiretroviral microbicide, showed that the gel reduced HIV infection by between 39% and 54% overall, depending on adherence. The study, which was published recently, also found that fewer women using tenofovir developed herpes, compared with the placebo group (29 compared to 58).
This was considered by the researchers to be an excellent secondary effect, because women with genital herpes are more likely to become infected by HIV.
Tenofovir also can be taken orally to inhibit reproduction of HIV. However, the oral version of the drug has not been shown to block the herpes simplex virus (HSV). Recently, the NIH announced the discontinuation of a tenofovir gel study because the gel was not more effective than placebo in preventing HIV.
“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,” said Leonid Margolis, PhD, head of the Section on Intercellular Interactions at the National Institute of Child Health and Human Development, Bethesda, MD, and one of the authors of the study.
Margolis and his collaborators examined the effects of tenofovir in a variety of tissue samples. They found that, after 12 days, levels of the HSV virus were between 1% and 13% of the virus level in untreated tissue. Tenofovir also blocked viral reproduction in tissue that was infected simultaneously by HIV and HSV.
Use of the gel in mouse models infected with HSV showed that the drug prevented symptoms and prolonged the animal’s survival.
The comparative potency of the vaginal gel compared with the oral form of the drug explains why the anti-HSV effects were not noticed sooner, Margolis said. The amount of tenofovir on tissues is 100 times greater when using the gel, compared with the drug taken orally.
1: Andrei G, Lisco A, Vanpouille C, Introini A, Balestra E, van den Oord J, Cihlar T, Perno CF, Snoeck R, Margolis L, Balzarini J. Topical Tenofovir, a Microbicide Effective against HIV, Inhibits Herpes Simplex Virus-2 Replication. Cell Host Microbe. 2011 Oct 4;10(4):379-89. PubMed PMID: 22018238; PubMed Central PMCID: PMC3201796.
Body Fluid Exposures Still Dangerous, Despite Prevention Efforts
Occupational exposures to blood and body fluids remain a danger, despite the increase in preventive measures over the past decade, according to research performed by the Infectious Disease and Infection Control office at the Washington VA Medical Center (DCVAMC).1
Researchers reviewed data from 1999 to 2008 at the DCVAMC, finding 564 incidents of occupational exposure to blood and body fluid (BBF). Of those, 66% were caused by needle sticks and 20% by sharp objects — two of the exposure methods targeted by prevention measures.
Exposures occurred most often in the acute-care setting, which accounted for 39% of exposures, and the operating room, which accounted for 22%. Housestaff accounted for the highest number of all exposure (35%), with 15.2 exposures per 100 housestaff.
The exposure rate remained steady during those 10 years, despite the increased use of anti-exposure devices and provider-education programs. The researchers concluded that targeting the specific occupational groups and hospital settings that have shown the highest risk should become a foundation of future preventive strategies.
1: Treakle AM, Schultz M, Giannakos GP, Joyce PC, Gordin FM. Evaluating a decade of exposures to blood and body fluids in an inner-city teaching hospital. Infect Control Hosp Epidemiol. 2011 Sep;32(9):903-7. PubMed PMID: 21828971.