Submitted to: World Buiatrics Congress and American Association Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/10/2002
Publication Date: 8/18/2002
Citation: Storz, J., Lin, X.Q., O=Reilly, K.L., Purdy, C.W., Loan, R.W. Coronavirus infections in the pathogenesis of shipping fever pneumonia. XXII World Buiatrics Congress and American Association Proceedings. 2002. p. 150-159.
Interpretive Summary: A bovine respiratory coronavirus (RBCV) appears to have been the main virus involved in two shipping fever pneumonia (SFP) outbreaks in feeder calves on consecutive years. Previously bovine respiratory coronavirus was not thought to be part of the SFP complex, whereas infectious bovine rhinotracheitis virus, bovine parainfluenza type-3 virus, bovine respiratory syncytial virus and bovine viral diarrhea virus were thought to be the viruses involved in SFP complex. The other two important parts of this multicomplex disease are the bacterial components, Mannheimia haemolytica and Pasteurella multocida and the stress of marketing and shipping the feeder calves. The disease cost the feeder calf industry a billion dollars a year in death losses and chronic lung lesions, and poor weight gains. The disease occurs after the calves have been shipped to the distant feedyards. The discovery of another virus involved in SFP is important to all involved in the feeder calf industry. It means that vaccines will have to be developed for the coronavirus, but first it must be determined what types of coronarviruses exist. It will have to be determined if a modified live virus or an inactivated virus product is best, and what type of adjuvant should be used. What route of vaccination is most effective? The bovine immune response to various respiratory and alimentary coronaviruses will have to be studied. It will also be difficult to convince the calf producer to vaccinate for another viral component of a disease complex that only occurs after the calves have been marketed and shipped to a feedyard.
Technical Abstract: Investigations of two natural epizootics of Shipping Fever Pneumonia (SFP) with sequential infections of Cornaviruses and Mannheimia (M) haemolytica and Pasteurella (P) multocida were studied. A prospectively designed and controlled parameters included clinical examinations, coordinated with nasal secretion and blood sampling, and virological, bacteriological as well as serological testing were applied to 105 and 120 weanling calves which developed SFP one year apart. Nasal mucus and blood samples were collected at a TN order buyer barn (OBB) before they were vaccinated with modified live virus vaccine of BHV-1 and PI3 in the first year and BHV-1 only in the last year. A 7-way clostridial vaccine and Ivomec were given to all calves, and a bacterin-toxoid of M. haemolytica was given to the odd-numbered calves of both years. The calves were transported 1932 kilometers to a research feedyard.in Bushland, TX. Nasal mucus swabs and serum samples were collected on feedyard days 1, 7, 14, 21, and 28 days. Necropsies were performed immediately after death, and lung samples were collected, and frozen at -85 C until titered for virus and bacteria. A refined virus isolation scheme was developed. The respiratory bovine coronavirus infections (RBCV) were detected on G clone of human rectal tumor cells (HRT-18).The RBCV were detected in 64 nasal mucus samples (year 1) and from 105 samples (year 2). Twenty-two calves contracted RBCV infection during transport to the feedyard and a total of 86 calves developed the infection in year 1. The 2nd epizootic yielded 89 RBCV isolates from nasal mucus of 120 calves on arrival at the OBB and 2 calves became infected with the virus during transport to the feedyard. In the 1st epizootic 93 of 105 calves developed fever and signs of respiratory tract disease and 10 deaths occurred in the feedyard. Febrile calves were treated with antibiotics. There were 107 calves with signs of respiratory tract disease in the 2nd epizootic and 16 deaths occurred. The virological, bacteriological, immunological, pathological, and histological findings in calves of these 2 SFP epizootics furnish compelling biological support for causative RBCV involvement.