In laboratory tests, the researchers found that the bacteria latched onto the sugar coating on the envelope that encases the virus particle and blocked infection. The bacteria also bound the sugar coating on immune cells, causing them to clump a feature that could render those harboring HIV incapable of infecting other cells.
"This discovery opens up a possible means of preventing the transmission of HIV from mother to infant through breast feeding," says Lin Tao, associate professor of oral biology at the UIC College of Dentistry, who directed the study in collaboration with colleagues at UIC and Rush University Medical School. Worldwide, mother-child transmission of HIV results in 800,000 new infections each year.
Tao and his colleagues screened hundreds of oral bacteria taken from the saliva of healthy volunteers before identifying six Lactobacillus strains that produced proteins capable of binding the particular type of sugar found on the HIV envelope, called mannose. The binding of the sugar normally enables the bacteria to stick to the mucosal lining of the mouth and digestive tract, forming colonization.
Further screening identified two strains capable of trapping live HIV viruses by binding with glycoprotein receptors, called gp120, in their viral envelope composed of protein spikes and a sugar "dome" rich in the mannose sugar. The sugar "dome" prevents HIV from being recognized by the human immune response, but it is the target of these lactobacilli. Each HIV virus has about 72 such glycoprotein receptors.
"The two strains were found to bind with several varieties of HIV
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Contact: Jim Sliwa
jsliwa@asmusa.org
202-942-9297
American Society for Microbiology
25-May-2004