Genetic Structure Determined for Pathogenic Spirochete

The complete genetic structures of 13 strains of the bacteria that cause Lyme disease have been resolved.

Lyme disease is the most frequent tick-borne disease in North America and Europe. There are multiple variants of Borrelia burgdorferi, the causative agent, but questions remain about how their variation correlates with different clinical manifestations.

A single genome sequence is not sufficient to understand the relationship between genotypic and geographic variation and disease phenotype. In a collaborative study carried out at the University of Medicine and Dentistry of New Jersey-New Jersey Medical School, (UMDNJ; Newark, NJ, USA), the whole genome sequence of 13 different isolates that span the range of natural variation has been determined. The strains were isolated from human and other natural sources.

New insights into Lyme disease are needed. While the bacterium that causes the disease has been known for 27 years, there still is no vaccine for humans available. The authors believe that their sequence information will help investigators design improved diagnostic tests and vaccines. Efficient tests are needed because the telltale rash on the skin does not always appear in infected patients. Cultures, which work well for many other bacteria, take too long to be of immediate use for Lyme bacteria. Serological and DNA assays have proven to be unsatisfactory. Therefore, these sequences should allow improved understanding of pathogenesis and provide a foundation for novel detection, diagnosis, and prevention strategies.

These new discoveries may accelerate research efforts to diagnose, prevent, and treat the disease, which can affect the nervous system, heart, skin, and joints. The occurrence of the disease has grown dramatically over the past ten years in the U.S. and Europe. There were nearly 30,000 new cases of Lyme disease reported in the U.S. in 2009, and cases have increased by 90% in the U.K.

Steven E. Schutzer, M.D., the senior author of the study, said, "A driving force for doing this project was the observation that certain forms of the bacteria can be more invasive than others. We wanted to find out why and how to identify this property".

The study was published in October 2010 in the Journal of Bacteriology.

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