Friendly bacteria in humans may protect against HIV
"I believe every life form has its natural enemy, and HIV should not be the exception," says Dr. Lin Tao, Associate Professor of the Department of Oral Biology, College of Dentistry, University of Illinois at Chicago. "If we can find its natural enemy, we can control the spread of HIV naturally and cost-effectively, just as we use cats to control mice."
The bacteria are strains of lactobacillus, commonly found colonizing the oral and vaginal cavities of humans. They do not cause disease. They target HIV because the virus is coated with the sugar mannose, which they use as a food source.
"Different bacteria have different sugar preferences," says Tao. "To block HIV, however, we needed to find bacteria that prefer the unusual sugar mannose and thus can capture it."
To identify bacteria that target mannose, Tao and his colleagues isolated oral and vaginal lactobacilli from healthy humans and tested the ability of different strains to bind to baker's yeast, another microorganism coated with mannose-rich sugars. They found a small group of lactobacilli that bound to mannose and further testing against HIV revealed two strains that specifically trapped the virus and blocked infection.
Due to high rates of mutation, repeated attempts at developing a vaccine to protect against HIV have failed. Inoculating the major mucosal surfaces where HIV transmission occurs with the HIV-capturing lactobacilli may provide a safe and cost-efficient method for preventing the spread of HIV, says Tao.
"This method can protect infants against HIV in breast milk and women against HIV upon sexual contact unobtrusively and inconspicuously via fermented foods or feminine products," says Tao. "If the method can be successfully developed and applied, the global spread of HIV can be controlled rapidly, effectively and safely."
"The major roadblock in the development of this technology is the lack of financial support. Drug companies and venture capitalists are not interested because the beneficiary populations are infants and women in poor countries," says Tao. He is currently seeking sponsorship from charities or philanthropists to develop this technology.
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Tao's colleagues include Sylvia Pavlova, Sarah Carlson, Michael Caffrey, and Amy Jacobs at UIC as well as Gregory Spear and Joshua Anzinger at Rush University, Chicago. The research was supported in part by AmFAR/Concerned Parents for AIDS Research, the National Institutes of Health (NIAID, NIDCR), and the International Association for Dental Research/GlaxoSmithKline Innovation in Oral Care Award.
The American Society for Microbiology, headquartered in Washington, D.C., is the largest single life science association, with 42,000 members worldwide. Its members work in educational, research, industrial, and government settings on issues such as the environment, the prevention and treatment of infectious diseases, laboratory and diagnostic medicine, and food and water safety. The ASM's mission is to gain a better understanding of basic life processes and to promote the application of this knowledge for improved health and economic and environmental well-being.
Científicos han encontrado una ''bacteria amiga'', ya presente en algunos seres humanos, que ataca al virus VIH y podría actuar como protectora contra la infección. El informe se presentó en la Conferencia 2005 de la Sociedad Norteamericana para el estudio de microbios benéficos en Microbiología. El Dr. Lin Tao, Profesor asociado del Departamento de Biología Oral de la Escuela de Odontología de la Universidad de Illinois en Chicago, declaró ''"Creo que toda forma de vida tiene sus enemigos naturales y el VIH no debe ser la excepción. Si podemos encontrar sus enemigos naturales, podremos controlar la expansión del VIH de forma natural y económicamente efectiva, igual que como usamos gatos para controlar a los ratones"''.

La bacteria es una cepa de lactobacillus, colonizador común de las cavidades orales y vaginales en los seres humanos. No produce enfermedad y ataca el HIV debido a que la capa externa de ''azúcar mannose'' del virus le sirve de alimento. Según el Dr. Tao, cada bacteria tiene sus preferencias de azúcares, por lo que es necesario encontrar la bacteria que prefiere la capa inusual de azúcar del virus HIV. El ''azúcar mannose'' es un monosacárido de fórmula C6H12O6, obtenido de mannan o por oxidación de mannitol.

Hasta ahora no ha sido posible crear una vacuna contra el SIDA debido a alta tasa de mutación del virus. Un tratamiento basado en la bacteria identificada podría ser utilizado para proteger a los niños al consumir leche maternal infectada y en cultivos administrados como comidas fermentadas o como productos de uso vaginal.