The women are protected by a weak inflammatory response in their vaginas

A research team lead by Dr. Michel Roger of the University of Montreal Hospital Centre and the university’s Department of Microbiology and Immunology has found that HIV-resistant sex workers in Africa have a weak inflammatory response in their vaginas – a surprise for the researchers, who were expecting the contrary considering the women’s high exposure to the virus. “In this part of the world, women represent over 60% of HIV cases, and this proportion continues to increase,” Roger said. “Studying women who are naturally resistant to the virus enables researchers to identify interesting information in terms of developing vaccinations or microbid gels that could prevent transmission of HIV.” The word microbid refers to something that is able to destroy microbes.

Roger has been working with women from Benin and Zimbabwe over the course of the past fifteen years in order to get a better idea of the immune and molecular mechanisms involved in the transmission of HIV. These countries were targeted because of the high number of infected women and the existence of natural resistance in some of them. The researchers found that when these women come into contact with the virus, the immune system cells in their vaginas produced fewer inflammatory molecules (cytokines and chemokines) than the same cells in HIV-infected women.

These molecules play a role in activating and recruiting “lymphocyte T-cells” that normally attack and destroy viruses. However, HIV is cunning and actually uses the T-cell to invade the body. “Fewer T-cells means fewer target cells available for the virus to use,” Roger explained.

Intriguingly, the researchers discovered that the immune response was very different in the women’s blood than in their vaginal mucous membrane. The findings show that it would undoubtedly be more effective to develop vaccinations that would block the virus at the entry point to the body rather than try to fight it once it is already established within the body’s system. “AIDS vaccination research has entirely focused on the blood stream and this approach has been a failure,” Roger said. “Our research shows that the immune response is different at the site of the infection, and that we should turn to the entry points in order to find a means for blocking the virus.” A vaccination of this kind could be administered via the nose and would immunize all mucus membranes in the body.

Research will continue in order to better understand the molecular mechanisms involved in the vaginal immune response. Scientists suspect that genetic factors may be at play, as it has been discovered that sisters living in similar circumstances have the same HIV-resistant profile.

Dr. Michel Roger’s latest published research in this area appeared in the September 2011 edition of PLoS One. The study “High Level of Soluble HLA-G in the Female Genital Tract of Beninese Commercial Sex Workers Is Associated with HIV-1 Infection” received funding from the Canadian Institutes of Health Research and the Réseau SIDA of the Fonds de la Recherche en Santé du Québec. The University of Montreal and the University of Montreal Hospital Centre are officially known as Université de Montréal and Centre hospitalier de l’Université de Montréal (CHUM), respectively.