“…Recently developed IgM specific assays (MACRIA) (Burkhardt, Reigel & Schilt, 1983;El-Hagrassy, Banatvala & Coltart, 1980;Morgan-Capner & McSorley, 1983;Pattison, 1983) for the diagnosis of enterovirus infections and other serological test systems such as complement-fixation (Bussel et al 1962;Halonen, Rosen & Huebner, 1959;Kraft & Melnick, 1952;Schmidt, Dennis & Lennette, 1962), haemagglutination-inhibition (Bussel et al 1962), immunodiffusion (Schmidt, Magoffin & Lennette, 1973), counterimmunoelectrophoresis (Minor et al 1979) or solid-phase immunoassays (Katze & Crowell, 1980a, b;King et al 1983) showed cross-reactivities of IgM antibodies to heterologous viruses. Apparently typespecific reactions in a 'reverse IgM RIA' were described by Torfason, Frisk & Diderholm (1984) using purified virions as antigen.…”