[Establishment of two competitive ELISAs for specific detection of bluetongue virus serotype 4].

To develop a clinical diagnosis technique for bluetongue virus infection, we established serotype-specific methods to detect serotype 4 of bluetongue virus (BTV-4). Two monoclonal antibodies (mAbs) against VP2 protein of BTV-4, named 4A-1G7 and 4B-1B6, were used as competitive antibodies in the competitive enzyme-linked immunosorbent assays (C-ELISA). We detected 50 negative serum samples from sheep, goats and cattle by C-ELISA. The cut-off values of 4A-1G7 and 4B-1B6 mAbs were 49% and 40%, respectively. The results of the sensitivity, specificity and repeatability by detecting standard positive serum, were consistent with the general standard of Office International Des Epizooties. Furthermore, serum samples of BTV-4, BTV-18 and BTV-20 infection could be screened out through the combined C-ELISAs by 4A-1G7 and 4B-1B6 mAbs. Thus, this technique may diagnose BTV-4, BTV-18 and BTV-20 infections.