February 23, 1998
Volume 50, No. 22
Female genital HIV different
HIV-1 virus found in the female genital tract is produced in the vagina and is slightly different from, although related to, HIV-1 virus produced in the blood, according to a study by Emory researchers.
Jeffrey Lennox, assistant professor of medicine and an infectious disease specialist, conducted four different studies of the HIV-1 virus in vaginal secretions and determined the virus was produced vaginally and not simply leaking into vaginal secretions through the blood. He presented his results at the annual Conference on Retroviruses and Opportunistic Infections in Chicago on Feb. 2.
Through the ongoing Emory Vaginal Ecology Study of HIV Infection project (called EVE), Lennox and his colleagues are trying to determine why and in what amounts HIV-1 is present in vaginal secretions.
"Studying HIV-1 in vaginal secretions is important for several reasons," Lennox said. "Since HIV-1 in the vagina is an important source of transmission to babies and to men in heterosexual relationships, obviously we want to try to reduce the amount of that virus."
Lennox first measured the amount of hemoglobin in vaginal secretions and the amount of virus in both vaginal secretions and blood in order to exclude the possibility that HIV-1 virus leaks passively from the bloodstream. He calculated that the amount of virus in the vagina that could be attributed directly to blood in vaginal secretions was less than 5 percent.
In a second test, Lennox studied women infected with the hepatitis C virus, an infection common in HIV-positive adults. In each woman there were more hepatitis C viral particles than HIV particles in the blood. In vaginal secretions, however, HIV particles exceeded hepatitis C virus particles. These results excluded passive leaking of HIV into vaginal secretions.
In a third study, he tested amino acid from the HIV virus in the blood and in the vagina. Lennox found in six of 11 women that the predominant HIV type in the vagina was different from that in the blood. Finally, Lennox cloned virus from the blood and from the vagina and found the majority of the vaginal clones were very similar to one another and less similar to the majority of blood clones.
"All these lines of evidence suggest that HIV-1 virus is actively produced in the vagina and is not just a result of leakage into the vagina through the bloodstream," Lennox said. "This knowledge is potentially important for vaccine developers. Most of the current HIV vaccine efforts are focused on viruses found in the blood, yet viruses in genital secretions are now the source of most transmitted viruses. If there are significant differences between viruses in the blood and in genital secretions, people designing vaccines would need to take that into account."