Important Research Shows HIV Can Penetrate Healthy Tissue
Researchers at Northwestern University have discovered how HIV can infect healthy women. Scientists have believed that the HIV virus was too large to penetrate healthy vaginal tissue until now. The current research from Northwestern University shows that healthy, intact genital tissue does not act as a barrier to HIV.
According to Thomas Hope, principle investigator and professor of cell and molecular biology at Northwestern University's Feinberg School of Medicine, "This is an unexpected and important result. We have a new understanding of how HIV can invade the female vaginal tract." He also says, "Our perspective is the viruses can infect people in more than one way." The research team is advocating that scientists look at the possibility that HIV might be transmitted directly through the skin.
Hope and colleagues discovered that HIV could permeate through the lining of the vaginal tract in the area where vaginal tissue normally sheds, as it is replaced by new cells. Dr. Hope says, "Until now, science has really had no idea about the details of how sexual transmission of HIV actually works." The research team observed how HIV opportunistically penetrated an area where the vaginal cells are not bound as tightly, in the squamous epithelium, or outer layer of the vaginal lining.
The scientists were able to watch HIV as it quickly passed through the cells to reach immune cells that were obtained for study purposes from animal models. The virus went through the epithelium in just four hours, traveling to a depth approximately equal to the width of a human hair. Hope explained, "As pieces of the skin flake off, that's the loose point in the system where the virus can get in."
Previously, researchers believed that HIV entered through a woman's cervical canal, but efforts to reduce the incidence of HIV in African women failed when a device was used to block the entrance to the cervix. Researchers have also noted that women with hysterectomy are still vulnerable to HIV.
Until now, it was believed that healthy, intact vaginal tissue protected women from becoming infected with HIV. The new research shows that HIV can be transmitted to women who have no tears, or breaks in the vaginal lining.
The implications of the research are important to all of us. Hope says, "Our perspective is the viruses can infect people in more than one way. We say one of those ways that needs to be in the equation is that the virus can be transmitted directly through the skin." The research team says it will be important to find out which cells are the first to become infected in the skin – a place where no one has been looking for HIV.
The research findings will be presented December 16 at the American Society for Cell Biology 48th annual meeting in San Francisco.