Evaluation of a new combined Western and line blot assay (EUROLINE-WB) for diagnosis and species identification of Echinococcus infection in humans.

Abstract

Serological detection of echinococcosis is crucial for diagnosis and management. We evaluated the new blot assay Euroline-WB (ELB, Euroimmun) which consists of a Western blot with Echinococcus multilocularis (E.m.) vesicle antigens and a line blot part with recombinant antigens from E. granulosus (E.g., genus-specific EgAgB) and E.m. (species-specific Em18 and Em95), in comparison to a commercial Western Blot (EWB, LDBio) for detection and species differentiation of echinococcosis within routine laboratory diagnostics. Thirty-five serum samples from 35 patients classified according to a standardized classification were included in the analysis. Out of 24 cases of proven and probable infection with E.m. or E.g. 16 (66.7%) and 15 (62.5%) were correctly identified on species level by EWB and ELB, respectively. False Echinococcus species were assigned in two cases by EWB but none by ELB. Negative blot results in patients with proven infections were noticed in 8.3% (ELB) compared to 4.2% (EWB), but were limited to patients with antiparasitic therapy or post-surgery indicating a treatment-induced loss of antibody activity. Thus, identification of Echinococcus infection at least on the genus level was possible in 23/24 (95.8%) and 19/24 (79.2%) of patients by EWB and ELB (or 22/24 patients (91.7%) including borderline results of ELB), respectively. Recombinant Em18 and Em95 were highly specific for detection of E.m. infection but differed in sensitivity (Em18 56% and 80 %, and Em95 22% and 20% in proven and probable infections, respectively). Advantages of ELB are the standardized analysis of the banding pattern by EUROLineScan software and a faster turn-around-time.