COMPARISON OF 2 IMMUNOASSAY PROCEDURES FOR DETECTING ENTEROVIRUS IGM

Enteroviruses cause significant illness in man but viral diagnosis is problematic. Enterovirus-specific IgM tests have been developed but du e to the difficulties of obtaining reliable control sera the interpret ation of assay data remains mainly arbitrary and empirical. The presen t study was undertaken to assess the reliability of such assays by com paring two tests performed independently in two different laboratories : a mu-capture radioimmunoassay (MACRIA) which utilizes S-35-labelled Coxsackie virus antigens and an enzyme immunoassay (EIA). A feature of the MACRIA was that sera were tested in one large batch whereas the E IA was in routine use in a reference laboratory. The MACRIA was easy t o perform but more suitable for research investigations than routine d iagnostic use. Similar results were detected in the majority of sera t ested in the two assays with 85% concordance achieved on testing 120 s era. Of the 18 discrepant results, 11 were positive by EIA only and 7 by MACRIA only. 89-95% concordance was obtained on testing sera agains t individual Coxsackie B1-5 serotypes, moreover 52% of the sera positi ve in MACRIA were reactive against only one viral antigen and the resu lts on certain of the more strongly reactive sera suggested the existe nce of a measure of type specificity in the MACRIA test. Qualitative d ifferences between the two tests high lighted problems of interpretati on in the absence of a gold standard and cautioned against sole relian ce on serology for diagnosis of enteroviral infections. (C) 1995 Wiley -Liss, Inc.