Heterogeneity of major proteins in Lyme disease borreliae: a molecular analysis of North American and European isolates.

We examined 46 isolates of Borrelia burgdorferi, the etiologic agent of Lyme disease and related disorders, with polyacrylamide gel electrophoresis and monoclonal antibodies. Our attention was on the OspA proteins, which are major proteins of the spirochete. There were at least four discernible phenotypes of the OspA protein. While 25 North American isolates were, with one exception, homogeneous in the type of OspA protein that they produced, 21 European isolates were heterogeneous in the types of OspA proteins represented. Only three European strains resembled North American strains in their OspA phenotype. Application of a deoxyribonucleic acid probe for an ospA gene demonstrated that the arrangement of ospA-associated sequences in the DNA differed between isolates.