A ONE-STEP SOLID-PHASE IMMUNOASSAY FOR SIMULTANEOUS DETECTION OF SERUM IGG AND IGM ANTIBODIES TO BORRELIA-BURGDORFERI

A one-step immunoassay for simultaneous detection of serum IgG and IgM antibodies to Borrelia burgdorferi has been developed. The assay is b ased on Clq, which binds to immune complexes containing IgG and/or IgM antibodies. Micro-beads pre-coated with antibodies to human Clq are m ixed with human serum samples and fluorochrome-labelled B. burgdorferi flagellum antigen. In the presence of serum IgG and/or IgM antibodies to B. burgdorferi, fluorochrome-labelled antigen/antibody complexes a re formed. These are then bound by serum Clq and are subsequently capt ured on the anti-C1q-coated beads. The sample is analysed on a flow cy tometer and the presence of fluorescent beads is, thus, indicative of a positive test result. In the present study the sensitivity and speci ficity of the assay are compared to those of the indirect IDEIA(TM) B. burgdorferi IgG and the mu-chain capture IDEIA(TM) B. burgdorferi IgM ELISAs for separate determination of IgG and IgM. Detection using a f low cytometer can be performed without separation of the beads from th e reaction mixture, which means that in practice, the method is carrie d out as a one-step assay and it is, thus, very suitable for automatio n. Other advantages of this kind of assay includes an antibody/antigen reaction which occurs in solution and the potential of using the meth od for the detection of antibodies against several antigens from the s ame or different infectious agents (multi-parameter screening). (C) 19 98 Elsevier Science B.V. All rights reserved.