[Rapid diagnosis of enterovirus 70 infection by detection of IgM antibodies with a biotin-avidin ELISA].

A biotin-avidin immunoassay was developed to detect IgM antibodies to enterovirus 70 (EV70) in sera from patients with acute hemorrhagic conjunctivitis. Biotinylated monoclonal antibody to EV70 and horseradish peroxidase-streptavidin were used in an indirect IgM capture ELISA. 40 acute- and convalescent-phase serum pairs were tested and 34 sera (85.0%) in the convalescent phase were positive for IgM antibodies. The positive rate of the method was much higher than that of the non-biotin-avidin system for EV70 (55%). Two sera in the acute phase, which were negative for neutralizing antibodies, had IgM antibodies. Two serum specimens which had been collected a third time from 2 patients during the seventh week after onset were positive for IgM, showing that EV70 IgM lasts at least for one month and a half. The biotin-avidin ELISA is sensitive and can be performed in 2 days instead of 3 days for the non-biotin-avidin method, and is useful for rapid diagnosis of EV70 infection.