MOLECULAR ANALYSIS OF SEQUENCE HETEROGENEITY AMONG GENES ENCODING DECORIN BINDING-PROTEIN-A AND BINDING-PROTEIN-B OF BORRELIA-BURGDORFERI SENSU-LATO

Immunization of mice with Borrelia burgdorferi decorin binding protein A (DbpA), one of two gene products of the dbpBA locus, has been shown recently to confer protection against challenge. Hyperimmune DbpA ant iserum killed a large number of B. burgdorferi sensu late isolates of diverse phylogeny and origin, suggesting conservation of the protectiv e epitope(s). In order to evaluate the heterogeneity of DbpA and DbpB and to facilitate defining the conserved epitope(s) of these antigens, the sequences of the dbpA genes from 29 B. burgdorferi sensu late iso lates and of the dbpB genes from 15 B. burgdorferi sensu late isolates were determined. The predicted DbpA sequences were fairly heterogeneo us among the isolates (58.3 to 100% similarity), but DbpA sequences wi th the highest similarity tended to group into species previously defi ned by well-characterized chromosomal markers. In contrast, the predic ted DbpB sequences were highly conserved (96.3 to 100% similarity). Su bstantial diversity in DbpA sequence mas seen among isolates previousl y shown to be killed by antiserum against a single DbpA, suggesting th at one or more conserved protective epitopes are composed of noncontig uous amino acids. The observation of individual dbpA alleles with sequ ence elements characteristic of more than one B. burgdorferi sensu lat e species was consistent with a role for genetic recombination in the generation of dbpA diversity.