STDs and Contracting HIV

April 3, 2009

Scientists researching HIV have found that when the virus attempts transmission via heterosexual intercourse the genital mucosa contribute to form a kind of genetic barrier against infection. They believe that any disruption of this mucosa places one at a much higher risk for HIV infection. STDs are known to cause an irritation of the genitals and this in turn causes a disruption of the genital mucosa. This state of affairs, say the scientists of a recent study, is the reason those with sexually transmitted diseases (STDs) are at even greater risk for HIV infection.

Just Diagnosed With HIV

Lead author of the study, Eric Hunter of Emory University, found 20 heterosexual couples just diagnosed with HIV and managed to obtain viral genetic sequences from each partner. The team looked at the env gene, which encodes the protein that creates the external layer of the virus. The env gene is the part of the virus that is most subject to variations. The research team discovered that around 90% of the couples were infected with only one strain of HIV, though the strain differed from case to case.

For the sake of comparison, the team brought in a group of just diagnosed individuals who had contracted the virus through contact with someone other than a spouse. There was greater variety in the number of viral sequences identified within this second group. Three out of seven individuals had been infected through more than one strain of the virus. Of the 42 just-diagnosed participants studied up until this point, the five infected by multiple strains were seen to have genital redness or ulceration upon examination by a physician.

The team believes that the barrier provided by the genital mucosa is worn down as STDs create inflammatory genital infections. Genital irritation interferes with the mucosal barrier and this allows multiple genetic variants of HIV-1 greater leeway to pass on through into the blood stream.

Heterosexual Couples and HIV

Finding just-infected participants was no easy task, but the team collaborated with the health programs run by Emory's Susan Allen of the Rollins School of Public Health. Through Allen's offices, thousands of Rwandan and Zambian heterosexual couples with one HIV-infected partner were enrolled in the study.

The study received funding through a combination of grants from the National Institutes of Health, the International AIDS Vaccine Initiative, and the Bill & Melinda Gates Foundation Grand Challenges Program.

 

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