Detection and differentiation of dengue-1 from Japanese encephalitis virus infections by ABC MAC-ELISA

An IgM antibody capture enzyme linked immunosorbent assay using avidin biotin complex system (ABC MAC-ELISA) was established for the detection and differentiation of dengue-1 and Japanese encephalitis virus infections. The cut-off value of MAC-ELISA was based on the mean value of optical density at 490 nm of seven negative human sera carried along in each assay multiplied by 2.1. The specificity of MAC-ELISA tested on 200 healthy enrolled male serum was 99.5% and 98.0% for dengue-1 and Japanese encephalitis IgM, respectively. Two hundred and sixty-six acute or followed-up dengue serum specimens which were identified to possess dengue-1 virus by virus isolation technique using C6/36 cell line and monoclonal antibody immunofluorescent assay (IFA) were tested by MAC-ELISA for IgM antibodies to dengue-1 and Japanese encephalitis virus infection. The positivity of IgM antibody for serum collected from day 1 to day 7 after onset of the disease was 0.0%, 0.0%, 7.6% 14.2%, 25.0%, and 77.7% by each consecutive day, correspondingly, for those collected from day 8 to two month was 96.7% overall. By comparison the P/N value of dengue-1 IgM to JE IgM, 98.5% and 96.8% of the dengue-1 and Japanese encephalitis suspected serum specimens could be distinguished from each other, respectively. MAC-ELISA is a convenient, rapid, sensitive and specific method for the detection and differentiation of dengue-1 from Japanese encephalitis virus infections.