EVALUATION OF A COMMERCIAL COMPETITIVE ELISA TEST KIT FOR THE DETECTION OF GROUP-SPECIFIC ANTIBODIES TO BLUETONGUE VIRUS

The performance of a competitive (c) enzyme-linked immunosorbent assay (ELISA) test kit, Blueplate Special(TM) (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 ha emorrhagic disease of deer virus (EHDV); 102 paired sem from cattle, s heep, and goats experimentally infected with the Australian isolates o f BTV, EHDV, and Palyam virus; 229 bovine and ovine samples of Canadia n origin (BTV free); and 562 bovine and ovine field samples from the U SA and Barbados (BTV endemic). Seroconversion was demonstrable by the BPS cELISA 10 days postinfection in all experimental animals inoculate d 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 i noculated with US and Australian isolates of EHDV and Palyam viruses c ross-reacted with the BTV antigen in the BPS cELISA. The total agreeme nt between the two assays for all the total bovine and ovine field ser a was 98.1%. The overall results substantiate the usefulness of the BP S cELISA test kit for monitoring animal sera for group-specific antibo dies to BTV. The slightly lower analytical sensitivity associated with the detection of antibody during early phase of infection in some ani mals would not be significant in the context of herd testing or any re gulatory program.