An Enzyme Immunoassay to Detect Australian Flaviviruses and Identify the Encephalitic Subgroup using Monoclonal Antibodies

Abstract

An antigen-capture enzyme-linked immunosorbent assay (ELISA) has been developed to detect antigens of Australian flaviviruses in mosquito pools, suckling mouse brain and infected cell culture supernatant fluid. A monoclonal antibody reactive to an epitope on the envelope glycoprotein common to all flaviviruses was used as the capture antibody. Purified rabbit IgG, produced against Murray Valley encephalitis (MVE) virus, which reacted with eight Australian flaviviruses in haemagglutination inhibition (HI) and in an indirect fluorescent antibody test, was used as the indicator antibody in direct and indirect antigen-capture ELISA. A monoclonal antibody specific for a subgroup of encephalitic flaviviruses was conjugated to horseradish peroxidase and used as the indicator antibody to distinguish MVE, Kunjin and Alfuy viruses from the remainder tested. This ELISA could detect viral antigen in mosquito cell culture fluids and suckling mouse brain preparations at titres as low as 1000 TCID₅₀/1001. Viral antigen in a single mosquito infected with MVE could be detected in a pool of 500.