Abstract
A single-dilution quantitative enzyme-linked immunosorbent assay (ELISA) system, based on commercial ELISA kits, for the simultaneous detection of seroconversion to bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus (BRSV), parainfluenza-3 virus (PI3V), and infectious bovine rhinotracheitis virus (IBRV) was evaluated by testing acute and convalescent serum pairs from 564 cattle in 145 outbreaks of respiratory disease. Seroconversion to BVDV, BRSV, PI3V and IBRV was detected in 8.0%, 19.0%, 13.7%, and 7.4%, respectively, of serum pairs tested. Seroconversion was detected in 60.7% of herds and 34.6% of animals tested. Infection with 2 or more viruses was found in 46.6% of these herds and in 27.2% of these animals. The majority of BVDV infections (62%) were associated with other virus infections, suggesting that BVDV may potentiate infection with other agents rather than being a primary pathogen of the respiratory tract. The results were compared with those obtained by virus neutralization and hemagglutination inhibition testing, and the sensitivity, specificity, and overall correlation were calculated. Sensitivities of 92%, 95%, 100%, and 100% were obtained for BVDV, BRSV, PI3V, and IBRV, respectively. The corresponding specificity values were 89%, 92%, 86%, and 91%. The overall correlation for each virus was 90%, 93%, 90%, and 93%, respectively. These results demonstrate that this ELISA system may be used successfully to detect seroconversion in serum pairs, highlight the frequency of multiple viral infections in outbreaks of respiratory disease, and provide further evidence of an immunosuppressive role for BVDV infections.