Development and evaluation of an IgM-capture ELISA for detection of recent infection with bluetongue viruses in cattle.

An IgM-capture enzyme-linked immunosorbent assay (ELISA) was developed for the detection of recent infection of bluetongue virus (BTV) in cattle. The test is based on the use of biotinylated capture anti-bovine IgM antibodies bound to a streptavidin-coated ELISA plate. The captured IgM antibodies were detected by application of BTV VP7 antigen and a VP7 antigen-specific monoclonal antibody. The IgM-capture ELISA was compared with the competitive ELISA by testing serum samples from groups of calves infected experimentally with five USA and 19 South Africa serotypes of BTV. The IgM-capture ELISA was able to detect bovine anti-VP7 antibodies from all animals infected with the 24 BTV serotypes at 10 days post-infection, whereas the competitive ELISA was not. When the detectable IgM diminished after 40 days post-infection by the IgM-capture ELISA, the IgG anti-VP7 antibodies remained high. The IgM-capture ELISA is sensitive and can be applied for the detection of recent infection of BTV in cattle.