Serodiagnosis of neuroborreliosis: Comparison of reliability of three confirmatory assays

The sensitivity and specificity of three confirmatory assays for the serodi agnosis of neuroborreliosis were investigated. Samples from 96 patients wit h proven neuroborreliosis, 80 healthy volunteers, 20 patients,vith neurosyp hilis and 20 patients with recent infections with Epstein-Barr virus (EBV) were tested for borrelial antibodies by immunoblotting, Borrelia burgdorfer i sensu lato sonicate EIA following pre-absorption of cross-reactive antibo dies (Abs-EIA) and by a so-called RECO-EIA using the following recombinant borrelial proteins as antigens: a 14 kDa-internal flagellin fragment, the o uter surface protein C (23 kDa) and the high molecular mass protein p83 (83 kDa), The immunoblots were evaluated according to the criteria published b y Engstrom et al, and Hauser et al, An evaluation of IgM and/or IgG antibod ies revealed a considerably higher sensitivity for the RECO-EIA (94%) compa red to the Abs-EIA (82%, P < 0.0001), Evaluation of the immunoblot accordin g to the criteria of Hauser was significantly more sensitive than according to the criteria of Engstrom (89 vs 51%, P = 0.0003), A higher sensitivity was demonstrated for IgM (54 vs 22%) and IgG antibodies (64 vs 24%), When b oth findings from RECO-EIA and immunoblotting were considered, positive fin dings in the first step assay (sonicate EIA without pre-absorption) were co nfirmed in 97% of patients. When samples were tested for IgM antibodies, th e specificities of the three confirmatory assays did not differ significant ly, but in the case of IgG antibodies, the immunoblot (Hauser: P = 0.013; E ngstrom: P = 0.004) and the RECO-EIA (P = 0.02) were more specific than the Abs-EIA, It is concluded that the immunoblot (evaluated according to Hause r) and the RECO-EIA are both suitable as confirmatory assays in the serolog ical diagnosis of neuroborreliosis. Monoclonal antibodies are mandatory too ls in the evaluation of the immunoblot.