Detection of bluetongue virus from blood of infected sheep by use of an antigen-capture enzyme-linked immunosorbent assay after amplification of the virus in cell culture.

An antigen-capture ELISA was used to detect bluetongue virus (BTV) from blood of infected sheep. A rabbit-origin capture antibody and a mouse-origin detection antibody combined with biotin-avidin amplification were used for the assay. The antigen-capture ELISA could not detect virus directly from the blood of infected sheep because of low virus titer. To enhance detection, virus from infected blood was amplified in cell culture. Virus could then be detected from cell culture supernatant fluids, using the ELISA. This amplification step increased the sensitivity of the assay comparable to that of assays performed in cell culture measuring cytopathic effects. The ELISA procedure was specific for BTV and did not mistakenly identify the antigenically related epizootic hemorrhagic disease virus. The antigen-capture ELISA permitted indirect quantitation and identification of BTV from the blood of infected sheep.