A double monoclonal antibody ELISA for detecting pestivirus antigen in the blood of viraemic cattle and sheep.

A panel of monoclonal antibodies (mAbs) has been produced to the p125/p80 non-structural polypeptide of border disease virus (BDV) and bovine virus diarrhoea virus (BVDV). This polypeptide appears to be highly conserved among BDV and BVDV isolates and consequently the mAbs directed against it have a broad cross-reactivity with pestivirus isolates. The epitope specificities of these mAbs were determined by competitive binding and four of the mAbs with mutually exclusive epitope specificities were selected for the development of a diagnostic ELISA. Two mAbs were used to capture virus antigen prepared from the blood of infected cattle and sheep, then two different mAbs used to detect the captured antigen. This double mAb ELISA was compared to existing ELISAs which rely on polyclonal antibodies (pAbs) for detecting captured antigen. The mAb detection ELISA was more sensitive than the pAb detection ELISAs for both cattle and sheep and resulted in higher optical densities for positive samples without an increase in background readings of negative controls.