Abstract
The performance of a competitive (c) enzyme-linked immunosorbent assay (ELISA) test kit, Blueplate Special@ (BPS), commercially produced by DiagXotics (Wilton, CT) for detection of group-specific antibodies to bluetongue virus (BTV) was compared with that of an internationally endorsed cELISA-I. A total of 1,026 serum samples were tested in this study: 133 samples from 23 calves and 3 sheep experimentally infected with South African isolates of 19 BTV serotypes and US isolates of 5 BTV serotypes and 7 calves infected with US isolates of 2 epizootic haemorrhagic disease of deer virus (EHDV); 102 paired sera from cattle, sheep, and goats experimentally infected with the Australian isolates of BTV, EHDV, and Palyam virus; 229 bovine and ovine samples of Canadian origin (BTV free); and 562 bovine and ovine field samples from the USA and Barbados (BTV endemic). Seroconversion was demonstrable by the BPS cELISA 10 days postinfection in all experimental animals inoculated with BTV, with the exception of 4 calves in which there was a delay of 10–20 days. Similar to the cELISA-I, none of the sera from calves inoculated with US and Australian isolates of EHDV and Palyam viruses cross-reacted with the BTV antigen in the BPS cELISA. The total agreement between the two assays for all the total bovine and ovine field sera was 98.1%. The overall results substantiate the usefulness of the BPS cELISA test kit for monitoring animal sera for group-specific antibodies to BTV. The slightly lower analytical sensitivity associated with the detection of antibody during early phase of infection in some animals would not be significant in the context of herd testing or any regulatory program.