Reactivity of enterovirus-specific IgM with infective and defective coxsackie B virions in patients with monotypic and multitypic IgM responses.

The antigenic specificity of enterovirus (EV)-specific IgM (EV-IgM) responses in patients with acute enterovirus infection was studied using an IgM-capture ELISA (EV-IgM ELISA) employing coxsackie B virus types 1-5 (CBV 1-5) antigens. Using antigens fractionated in caesium chloride (CsCl) gradients, and monoclonal antibodies (mAbs) and polyclonal antisera of defined specificity as detector antibody to detect IgM-bound antigen, IgM of single serotype specificity was shown to react consistently with dense, infective virions. When responses were directed against multiple CBV serotypes, IgM reacted consistently with lighter, defective virions. Serotype-specific mAbs and polyclonal antisera reacted with a range of determinants, some present only on infective virions, some only on defective virions, and others which were common to both types of virion. Common EV group determinants were confined to defective virions. Neither infective nor defective virions of any one serotype reacted with IgM from all patients with EV infection. An assay capable of detecting EV-IgM in all EV infections will require an antigen cocktail incorporating a wide range of determinants, rather than a single group EV antigen.