Current serodiagnostic assays for
Lyme disease are inadequate at detecting early
infection due to poor sensitivity and nonspecificity that arise from the use of whole bacteria or
bacterial proteins as assay targets; both targets contain
epitopes that are cross-reactive with
epitopes found in
antigens of other bacterial species. Tests utilizing
peptides that contain individual
epitopes highly specific for Borrelia burgdorferi as diagnostic targets are an attractive alternative to current assays. Using an overlapping
peptide library, we mapped linear
epitopes in
OspC, a critical
virulence factor of B. burgdorferi required for mammalian
infection, and confirmed the results by
enzyme-linked
immunosorbent assay (ELISA). We identified a highly conserved 20-amino-acid
peptide epitope, OspC1. Via ELISA, OspC1 detected specific
IgM and/or
IgG in 60 of 98 serum samples (62.1%) obtained from patients with
erythema migrans (early
Lyme disease) at the time of their initial presentation. By comparison, the commercially available
OspC peptide PepC10 detected antibody in only 48 of 98 serum samples (49.0%). In addition, OspC1 generated fewer false-positive results among negative healthy and diseased (
rheumatoid arthritis and positive Rapid Plasma
Reagin [RPR+] test result) control populations than did PepC10. Both highly specific and more sensitive than currently available
OspC peptides, OspC1 could have value as a component of a multipeptide
Lyme disease serological assay with significantly improved capabilities for the diagnosis of early
infection.