NEW YORK (Reuters Health) May 25 - Colonizing an infant's digestive tract
with mannose-binding Lactobacillus may protect them from HIV present in
breast milk, according to a presentation at the American Society for
Microbiology general meeting in New Orleans.
Because maternal treatment before delivery prevents vertical transmission,
breastfeeding now represents the major source of infant infections in
Africa, causing approximately 800,000 new infections annually, Dr. Lin Tao
told Reuters Health.
Because conventional prophylaxis with antiretrovirals, microbicides, or
vaccines cannot be used in infants, "we sought to block HIV transmission
from mother to child using a more innovative approach," added Dr. Tao, of
the University Illinois at Chicago College of Dentistry. Lactobacillus, a
common commensal in the GI tract and the vagina of adults, seemed to be
such an option.
The researchers obtained saliva samples from more than 100 healthy
volunteers, from which they isolated 170 Lactobacillus strains. Nine were
capable of binding to mannose in Saccharomyces cerevisiae, which was used
as a surrogate for HIV.
The strain with the highest affinity for the yeast, L. fermentum OLB-19a,
also binds to HIV glycoproteins and to T and B lymphocytes and dendritic
cells, the investigators found. The bacteria prevented immune cell
infection by HIV.
Because "the stomach and intestine is where active absorption of milk takes
place, it will be very important to have the bacteria in the oral cavity
and throughout the intestinal tract," Dr. Tao explained. To that end, his
group is attempting to develop lyophilized Lactobacillus that can be
administered to infants.
Their current research was funded by the National Institutes of Health, the
researcher noted. The group's challenge now is to find a sponsor to fund
the next steps in developing a product. Because the intent is to distribute
the Lactobacillus preparation in underdeveloped countries, it is unlikely
that a pharmaceutical company will be interested in investing in a product
unlikely to earn a profit, Dr. Tao said.
But if this approach works, freeze-dried Lactobacillus has the potential to
prevent half a million infections annually, he added.

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