Distinct levels of genetic diversity of Borrelia burgdorferi are associated with different aspects of pathogenicity

Different species of pathogenic Borrelia show different symptoms and tick v ector specificity. Even within regions where only one species is found, Lym e disease progresses very differently from one patient to another. Since Bo rrelia shows very little recombination either within or between species, al leles of a gene can be used to mark clones. The ospC gene is highly variabl e within each species and can be used to define groups of related clones. I t has been previously shown that only four out of seventeen ospC groups of Borrelia burgdorferi sensu stricto cause invasive forms of the disease. Oth er groups cause erythema migrans, a skin rash at the site of the tick bite, but not invasive disease, while still other groups seem to be nonpathogeni c to humans. In this study we extend the analysis of the ospC gene to the o ther pathogenic species, Borrelia garinii and Borrelia afzelii. Only two gr oups in B. afzelii and four groups in B. garinii cause invasive disease. Th us, only ten out of the 58 defined ospC groups cause invasive and presumabl y chronic Lyme disease. (C) 2001 Editions scientifiques et medicales Elsevi er SAS.