title: Nonstructural protein 1 antibody-based epitope-blocking enzyme-linked immunosorbent assay to differentiate Japanese encephalitis virus from dengue virus infections in humans.
abstract: Japanese encephalitis virus (JEV) and the four dengue viruses (DENV1-4) are co-distributed in Southeast and South Asia. Since JEV is antigenically cross-reactive with DENV1-4, the differentiation between these viruses using antibody assays may be difficult. Herein, we describe the development of an epitope-blocking enzyme-linked immunosorbent assay (ELISA) using a monoclonal antibody specific for the nonstructural protein 1 (NS1) of JEV (JEV-NS1) to differentiate antibodies against JEV from those against DENV1-4. Hyperimmune mouse sera against JEV-NS1 showed >60% inhibition, whereas those against NS1 of DENV1-4 showed <30% inhibition. The present assay could therefore detect antibodies specific for JEV. For testing of human sera, a temporary cutoff value (30.8%) was calculated the average and standard deviation obtained for sera of control humans negative for JEV antibodies. Human sera positive for antibodies to any of DENV1-4 NS1 but negative for antibodies to JEV-NS1 showed a lower percentage inhibition than the cutoff value. On the other hand, sera with JEV-NS1 antibody levels of ≥0.400, as determined by the conventional ELISA (medially/strongly positive for JEV-NS1 antibodies), showed percentage inhibition greater than the cutoff. Although this blocking ELISA afforded false-negative results for most sera that were weakly positive for JEV-NS1 antibodies, it may be useful for investigating the seroepidemiology of JEV antibodies in dengue-endemic areas.
authors.affiliation: Division of Infectious Diseases, Department of International Health, Kobe University Graduate School of Health Sciences, Kobe 654-0142, Japan. ekon@kobe-u.ac.jp
authors.forename: Eiji
authors.initials: E
authors.lastname: Konishi
authors.forename: Mayu
authors.initials: M
authors.lastname: Konishi
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood*; D002522:Chlorocebus aethiops; D003715:Dengue / Q000175:diagnosis* / Q000276:immunology; D003716:Dengue Virus / Q000276:immunology / Q000302:isolation & purification; D003937:Diagnosis, Differential; D004664:Encephalitis Virus, Japanese / Q000276:immunology / Q000302:isolation & purification; D004672:Encephalitis, Japanese / Q000175:diagnosis* / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D000939:Epitopes / Q000276:immunology; D006801:Humans; D051379:Mice; D011817:Rabbits; D012680:Sensitivity and Specificity; D014709:Vero Cells; D017361:Viral Nonstructural Proteins / Q000097:blood* / Q000276:immunology
chemical_list: D000914:Antibodies, Viral; D000939:Epitopes; D017361:Viral Nonstructural Proteins