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Different species of spirochetes cause human diseases ranging from syphilis to Lyme disease, and Chunhao (Chris) Li, an assistant professor in UB’s Department of Oral Biology, has secured more than $1.6 million to study these tiny creatures.
Funding from the American Heart Association and four concurrent grants from the National Institutes of Health—two from the National Institute of Allergy and Infectious Diseases and two from the National Institute of Dental and Craniofacial Research—are supporting Li’s research into spirochetes. In particular, Li is studying Borrelia burgdorferi, the species responsible for Lyme disease, and Treponema denticola, a species strongly associated with periodontal disease.
Li joined UB in 2005 after completing postdoctoral research and teaching at West Virginia University, where he worked with Nyles Charon, one of the world’s leading experts on spirochetes. A native of China who studied and taught at the Chinese Academy of Preventive Medicine in Beijing before moving to the U.S. to continue his work, he now directs his own lab at UB.
Li started research on spirochetes after graduating from medical school in China and working in a hospital for two years. He was interested in infectious diseases and went to graduate school for more study; his mentor and PhD director was an expert on spirochetes, and that set Li on his career path.
Li’s research on Treponema denticola investigates how this bacterium dodges the human immune response. He and his team have discovered that a protein the bacterium produces can cleave human antibodies, which alert the human body to the presence of foreign pathogens. The protein also can prevent the activation of polymorphonuclear leukocytes, a type of white blood cell that can destroy bacterial cells.
One of Li’s recent research successes is the development of a reliable method for producing genetic mutants of Treponema denticola in large enough quantity to study.
In Borrelia burgdorferi, Li is studying motility and chemotaxis—the bacteria’s ability to move in particular directions and select destinations—and the roles that these characteristics play in causing disease. Spirochetes are shaped like long coils and travel with a wave-like motion. Reversing course requires the coordination of their flagella from each end. In earlier research, Li showed in a mouse model that removing a gene that codes a protein essential for that coordination prevented the bacteria from causing disease.
In a different line of inquiry, Li is examining another potentially exploitable vulnerability: the internal signaling that allows Borrelia burgdorferi to switch genes on and off to adapt to the host environments of human and tick, with their different temperatures and immune responses. Li has described a two-component signal sequence. Interrupting either component presumably would prevent the spirochete from infecting people.
From UB, Li is making discoveries with the potential to improve the health of people around the world.
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