ANALYSIS OF THE HUMAN-ANTIBODY RESPONSE TO OUTER SURFACE PROTEIN-C (OSPC) OF BORRELIA-BURGDORFERI SENSU-STRICTO, B-GARINII, AND B-AFZELII

The aim of this study was to determine by Western blotting (WE) the pr evalence of anti-outer surface protein C (OspC) IgM and IgG antibodies in patients with Lyme borreliosis according to each of the three geno species of Borrelia burgdorferi sensu late. Strains of B. burgdorferi sensu stricto (MUL), B. garinii (DK6), and B. afzelii (DK26) served as antigen, all of which expressed abundant OspC. We examined sera from 117 patients with untreated early and late Lyme borreliosis, as well a s from 100 blood donors and 29 patients with syphilis. WE results were compared with the B. burgdorferi flagellum enzyme-linked immunosorben t assay (ELISA) data. OspC from B. burgdorferi sensu stricto showed th e lowest diagnostic sensitivity. OspC from B. garinii and B. afzelii p erformed almost identically in erythema migrans, with an IgM positive rate of 36% versus 34%, whereas OspC from B. garinii performed best in neuroborreliosis (60% versus 44%). The anti-OspC IgG response was les s prominent than the IgM response and was infrequent in the late stage s of the disease (0-20%). The benefit of combining the evaluation of a nti-OspC responses with all three species was limited. The overall dia gnostic sensitivity of WE anti-B. garinii OspC evaluation was, in the early stages of the disease, comparable to the results obtained using the flagellum ELISA. In erythema migrans and neuroborreliosis, the add ition of anti-OspC IgM to the flagellum ELISA increased the sensitivit y by 15% and 10%, respectively. It can, therefore, be concluded that O spC from B. garinii is a suitable OspC test antigen, and that suppleme ntary use of OspC from other species adds little to the overall diagno stic sensitivity. An ELISA based on B. garinii OspC and native flagell a seems currently the most promising concept for a future antibody tes t in early Lyme borreliosis.