Characterization of Antigenic Determinants of Borrelia burgdorferi Shared by Other Bacteria

Three antigenic determinants of Borrelia burgdorferi that were shared with other spirochetes and gram-negative bacterial species, as measured by Western blot, ELISA, or both, were identified and characterized using monoclonal antibodies (MAbs). Two were associated with immuno-genic integral membrane lipoproteins of 19- and 22-kDa, respectively, by [³H]palmitate incorporation and Triton X-114 phase partitioning. A third antigenic determinant was shown to be associated with a 72-kDa heat shock protein that was also immunogenic in human patients. MAb agglutination assays with B. burgdorferi and treatment of the spirochete with proteases indicated that none of the antigenic determinants were surface exposed. NH₂-terminal sequence analysis revealed the 72-kDa protein to have 100% identity with the first 13 amino acid residues of the Escherichia coli dnaK heat shock protein. The presence of these and other shared antigenic determinants in ELISA antigen preparations could explain the high degree of serologic cross-reactivity in current diagnostic procedures.