ASSESSMENT OF THE SPECIFICITY OF A COMMERCIAL HUMAN PARVOVIRUS B19 IGM ASSAY

Background: It is important to investigate a possible cross-reaction o f anti-rubella IgM in the IDEIA(TM) Parvovirus B19 IgM test because ma ny B19 infections are either asymptomatic or have clinical symptoms si milar to those of rubella virus infections. Epstein-Barr virus (EBV) I gM, cytomegalovirus (CMV) IgM, measles IgM and rheumatoid factor (RF) IgM cross-reactions were also studied. Objectives: In the period from February to September 1994 (including a parvovirus B19 epidemic) more than 10 000 serum samples were examined for parvovirus B19 IgM in Denm ark. This gave an opportunity to evaluate the commercial IDEIA(TM) Par vovirus B19 ELISA kit (DAKO A/S, Glostrup, Denmark), which was used ro utinely at Statens Serum Institut from the beginning of 1994 and onwar ds. Study design: A total of 123 parvovirus B19 IgM positive sera were tested for reactivity in rubella IgM EIA. A total of 78 rubella IgM p ositive sera, 60 EBV VCA-IgM positive sera, 30 CMV IgM positive sera a nd 24 measles virus IgM positive sera were tested for reaction in IDEI A(TM) Parvovirus B19 IgM test. Finally, 25 parvovirus IgM positive ser a were tested for specific IgM against measles virus, EBV (VCA), CMV a nd for RF. Results: One anti-B19 IgM positive serum sample reacted pos itively in the rubella IgM test. Of rubella IgM positive serum samples 4% cross-reacted in IDEIA(TM) Parvovirus B19 IgM test, as did 17 and 20% of EBV VCA-IgM and CMV IgM positive serum samples respectively. No ne of measles virus IgM positive serum samples cross-reacted in the ID EIA(TM) Parvovirus B19 IgM test. Of 25 initially parvovirus B19 IgM po sitive sera 20% cross-reacted in EBV VCA IgM test and 8% in the CMV Ig M test. None reacted positively in measles virus IgM test; 28% showed weak reactivity in RF IgM test. Conclusions: Precautions must be taken when results of IgM assays are interpreted. Epidemiological and clini cal observations must be considered. (C) 1997 Elsevier Science B.V.