|RIDPATH, JULIA - Retired ARS Employee|
|FULTON, ROBERT - Oklahoma State University|
|BAUERMANN, FERNANDO - South Dakota State University|
|WELCH, JENNY - Zoetis|
|CONFER, ANTHONY - Oklahoma State University|
Submitted to: Journal of Veterinary Diagnostic Investigation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/2/2018
Publication Date: 6/2/2020
Citation: Ridpath, J., Fulton, R.W., Bauermann, F.V., Falkenberg, S.M., Welch, J., Confer, A.W. 2020. Sequential exposure to bovine viral diarrhea virus and bovine coronavirus results in increased respiratory disease lesions: clinical, immunologic, pathologic, and immunohistochemical findings. Journal of Veterinary Diagnostic Investigation. 32(4):513-526. https://doi.org/10.1177/1040638720918561.
Interpretive Summary: Bovine respiratory disease complex (BRDC) involves contribution of a variety of both viral and bacterial pathogens as well as environmental factors and stress that leads to a compromised immune system. In general single pathogen infection models do not reproduce the clinical presentation associated with the BRDC. The current study evaluated both single and dual infection models with bovine viral diarrhea virus (BVDV) and bovine coronavirus (BoCV) to determine if dual infections potentiate the severity of disease. Dual infections with BVDV and BoCV resulted in more severe in gross and microscopic lesions than single infections with either pathogen. Dual infection models may be more useful than current models for the study of BRDC.
Technical Abstract: Problem addressed; Bovine respiratory disease complex (BRDC) likely results from simultaneous or sequential infections with multiple pathogens. While, bovine viral diarrhea virus (BVDV) and bovine corona virus (BoCV) are frequently isolated from cattle suffering from BRDC, animal models based on single infection with either virus have had limited success in reproducing respiratory disease. Objective; Determine if sequential dual infections with BVDV and BoCV resulted in more severe respiratory disease than single infections with either virus. Methods and approach; Colostrum deprived Holstein calves, at least two weeks of age were exposed to mock inoculum, BVDV alone, BoCV alone, BoCV followed 4 days later by BVDV and BVDV followed 4, 6 or 9 days later by BoCV. Body temperature, viremia, viral shed, seroconversion and changes in circulating immune cells were monitored. Lung and immune tissue were compared at necropsy. Results; Single BVDV infections reduced both thymus size and level of circulating lymphocytes while single BoCV infections increased circulating lymphocyte numbers and had no effect on thymus size. Pyrexia was associated with exposure to BVDV either as a single infection or in dual infections. Lung lesions were observed when calves were exposed to BoCV followed 3 days later by BVDV or BVDV followed 6 or 9 days later by BoCV. The observed lung lesions (both microscopic and macroscopic) are consistent with a mild to moderate interstitial pneumonia. Conclusions; Sequential dual infections with BVDV and BoCV result in gross and microscopic lesions that are more severe than those seen in single infections with either pathogen. The lesions observed in dual infections were consistent with mild respiratory disease.