‘Good Guy’ Germs Could Defeat HIV

An opportunity to immunize people in developing countries where HIV is spreading so rapidly.

The word “bacteria” often conjures up images of germs and infections, but NC State researchers are trying to use beneficial bacteria to stop a deadly infection in its tracks. Drs. Todd Klaenhammer and Gregg Dean are working to develop an oral immunization strategy to eventually vaccinate people against HIV, which the Joint United Nations Programme on HIV/AIDS (UNAIDS) says has killed more than 25 million people worldwide in the last 30 years. Another 33 million people, including about 2 million children, are infected.

Klaenhammer, William Neal Reynolds Distinguished Professor of Food Science, Microbiology and Genetics, has worked for decades with lactic acid bacteria, used as starter cultures and probiotics in fermented foods and dairy products, to improve the healthful benefits of foods. The “good guy bacteria” make a perfect delivery system for oral vaccines, he says, because someone can ingest millions of the microbes safely in a single spoonful and they can survive through the stomach, where digestive acids normally break down protein-based vaccines. “When you eat that many bacteria,” Klaenhammer says, “they can literally cover the small intestine, one of the most important immunological organs in the body.”

By genetically modifying the bacteria, Klaenhammer and Dean are attempting to generate lactobacilli that secrete HIV-responsive vaccines. Klaenhammer used this approach to develop an effective oral vaccine for anthrax in mice. Dean’s research team now is investigating the most efficient way of delivering an oral HIV vaccine to the immune-system cells in the intestinal tract. Using a two-year, $207,000 Recovery Act grant from the National Institutes of Health, Klaenhammer and Dean hired a research associate and bought equipment for the labor-intensive process of counting bacterial colonies, which frees lab personnel for other tasks.

A professor of immunopathology in the College of Veterinary Medicine, Dean works with mice to test the bacterial delivery system. He found that enough antibodies were produced in the intestinal and vaginal tracts of some mice to induce an immune response to HIV. Fewer than half of infected people in developed countries receive the drugs needed to live with HIV, UNAIDS says. Numbers are significantly lower in areas where people cannot afford and don’t have access to treatment. “The bacteria are so efficient at producing the immunogenic HIV proteins that a vaccine would cost pennies per person,” Dean says. “We think this presents an opportunity to immunize people in developing countries where HIV is spreading so rapidly.”

 

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Drs. Gregg Dean, left, and Todd Klaenhammer are working toward an oral immunization for HIV.