December 18, 2008
A new study has found that HIV appears to attack normal, healthy genital tissue in women and does not require breaks in the skin to infiltrate cells, offering new perspectives on how the virus is spread, researchers said on Tuesday, Reuters reports. Thomas Hope, a study author from Northwestern University's Feinberg School of Medicine, said that scientists have had little detailed understanding of how HIV is transmitted sexually in women and that it was "previously thought there had to be a break in [genital tissue] somehow" for women to contract the virus. He added that the study's findings show that "[n]ormal skin is vulnerable."
For the study, researchers in a partnership between Northwestern and Tulane University introduced HIV -- which carried fluorescent, light-activated tracers, a new method developed to better see how the virus worked -- to newly removed vaginal tissue taken from hysterectomy surgeries. A microscope was used to observe the virus as it penetrated the outer lining of the female genital tract -- also called the squamous epithelium -- and found that HIV was able to move quickly past the skin barrier to reach immune cells. The process also was observed in nonhuman primates, according to Reuters. In addition, the results of the study suggest that HIV focuses on areas of the genital tissue where skin cells recently had been shed, Hope said (Steenhuysen, Reuters, 12/16). Hope said the results are "an important and unexpected result -- we have a new understanding of how HIV can invade the female vaginal tract." He added, "We urgently need new prevention strategies or therapeutics to block the entry of HIV through a woman's genital skin" (BBC News, 12/17).
According to Reuters, researchers in the past have assumed that HIV sought out breaks in the skin -- like a herpes sore -- to gain access to immune system cells deeper in tissue, and some thought the normal lining of the vaginal tract could work as a barrier to transmission during sexual intercourse. Reuters reports that the study "casts doubt" on the theory that HIV transmission requires a break in the skin or that the virus gains access through the cervical canal's single layer of skin cells. The findings also "might explain why some prevention efforts" -- such as diaphragms or herpes treatment -- have "failed," Reuters reports (Reuters, 12/16).
Reprinted with permission from kaisernetwork.org. You can view the entire Kaiser Daily HIV/AIDS Report, search the archives, or sign up for email delivery at www.kaisernetwork.org/dailyreports/hiv. The Kaiser Daily HIV/AIDS Report is published for kaisernetwork.org, a free service of the Kaiser Family Foundation, by The Advisory Board Company. © 2008 by The Advisory Board Company and Kaiser Family Foundation. All rights reserved.