Diagnostic performance of the ZEUS Borrelia VlsE1/pepC10 assay in European LB patients: a case-control study

This retrospective case-control study assesses the sensitivity, specificity, and area under the curve of the ZEUS Borrelia VlsE1/pepC10 assay in comparison with the C6-ELISA in European patients with Lyme borreliosis, healthy blood donors, and potentially cross-reactive controls. We included a convenience series of 161 sera from patients with physician-confirmed early localized or disseminated Lyme borreliosis (n = 143), 400 sera from healthy blood donors and 44 sera with potentially cross-reactive antibodies, on which we performed the aforementioned serological assays and the recomLine immunoblot. Diagnostic parameters were compared in various single-tier and two-tier algorithms. The specificities of the C6-ELISA and the ZEUS Borrelia VlsE1/pepC10 were comparable in healthy blood donors (e.g., single-tier permissive: C6: 362/400, 90.5% [87.2-93.2]; VlsE1/pepC10: 361/400, 90.3% [86.9-93.0]). The C6-ELISA had an apparently higher sensitivity in EM sera (e.g., both time points combined: C6: 61/76, 80.3% [69.5-88.5]; VlsE1/pepC10: 54/76, 71.1% [59.5-80.9]), but these differences were all not-significant. Interestingly, the VlsE1/pepC10 assay had a significantly higher specificity in sera with potentially cross-reactive antibodies (e.g., single-tier permissive: C6: 34/44, 77.3% [62.2-88.5]; VlsE1/pepC10: 40/44, 90.9% [78.3-97.5]; p = 0.031). While the areas under the curve for both assays were excellent, that of the C6-ELISA exceeded that of the VlsE1/pepC10 (C6: AUC = 0.925; VlsE1/pepC10: AUC = 0.878; p = 0.003). The novel ZEUS Borrelia VlsE1/pepC10 assay has generally comparable diagnostic parameters to the C6-ELISA with potentially improved specificity in cross-reactive sera. Thus, it is a useful tool for the serodiagnosis of Lyme borreliosis in Europe.