Crystal Structure Obtained for Lyme Disease Antigen

Crystal structure analysis of the variable surface antigen VlsE of Borrelia burgdorferi (the Lyme disease bacterium) has revealed that changeable regions of the protein are largely exposed on the surface of the molecule while invariant regions are masked within the protein. These findings were published in the June 14, 2002, issue of the Journal of Biological Chemistry.

The six variable regions lie mainly on the surface and mask the invariant regions from the host immune system. These changing areas may allow Lyme disease to stay a step ahead of the host's defenses by confounding the ability of antibodies to bind to VlsE and hence destroy the bacterium. The crystal structure analysis was performed by researchers at Texas A&M University (College Station, USA).

The structural information helps to explain why antibodies fail to clear the host of the bacteria. Response of the variable regions is ineffective, as this area changes, nullifying the ability of antibodies to bind to it. The unchanging regions, which could be successfully targeted by the immune system, are hidden and not available to antibodies.

Research on the protein has provided a highly accurate avenue for diagnosing the disease, which can be difficult to recognize in many cases, according to co-senior author Dr. Steven J. Norris, professor of pathology and laboratory medicine at the University of Texas-Houston Medical School (USA). The findings also explain in part the tenacity of Lyme disease, which can survive in a host for years if left untreated.