University of Manitoba scientists may be a step closer to unlocking the mystery of why some women are immune to the virus that causes AIDS.
The discovery could lead to vaccines or treatment for people who aren't so lucky in their genetic makeup.
U of M researchers, along with participants from Winnipeg's National Microbiology Laboratory and the University of Nairobi in Kenya, have identified more than 15 proteins in Kenyan sex workers that appear to be markers for natural immunity to infection with the human immunodeficiency virus.
The results of their study were published Wednesday in the Journal of Proteome Research.
Using the analogy of a combination lock, the 15 proteins may be all or part of a combination that represents immunity to HIV in women.
The researchers found eight proteins to be much more abundant in a group of women apparently resistant to HIV. These proteins are known to have anti-viral properties which may prevent HIV from reproducing, or anti-inflammatory abilities that help prevent infection by the virus.
"We think that if you can trigger 'good immune responses' (with one or more proteins), that might be what is protecting these women," said Blake Ball of the U of M's department of medical microbiology.
Researchers also found about seven other proteins to be diminished in HIV-resistant women.
They hope to eventually use the information about the proteins to help develop a vaccine or microbicide to prevent HIV infection.
The key now is to test a wider group of women to confirm the set of proteins and then to identify the specific role of each one, Ball said, though he cautioned that some of the proteins and other factors may act together rather than individually.
Scientists are studying HIV-resistant groups of people in other areas of the world, Ball said, including intravenous drug users, sex workers, and couples in which one partner is HIV-positive and the other is not.
"That's also one of the important next steps -- to see if other people who study similar groups to us can replicate our findings," Ball said.
During the study, researchers collected and analyzed samples of vaginal fluid from Kenyan commercial sex workers about 35 to 45 years old who have been exposed to HIV.
Some of these women appear to be resistant to HIV infection. They have been active in sex work for several years, but have not shown any sign of infection. Previous studies have shown that the longer these women work as prostitutes, the more their apparent immunity increases.
Samples from 10 HIV-resistant women were compared with those from 10 other female sex workers who were infected, as well as to samples from a control group of women not involved in prostitution.
The HIV-resistant sex workers in this study are part of a larger population of about 140 HIV-resistant women in Kenya known to researchers. All are from a group of 2,000 Kenyan sex workers referred to as the Pumwani cohort that scientists at U of M and the University of Nairobi have been studying since 1980.
will.tremain@freepress.mb.ca
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