1a.Objectives (from AD-416):
Compare clinical presentation following infection with different strains of bovine corona virus.
1b.Approach (from AD-416):
Five to six week old colostrum deprived calves will be exposed to one of seven field strains of bovine corona virus. Clinical signs will be monitored including basal temperature, circulating white blood cells and shedding of virus in nasal and rectal swabs. At six days calves will be necropsied and their lungs scored for lesions.
Vaccines against bovine corona viruses (BoCV) were first developed more than 40 years ago. Vaccines on the market today use the same viruses that were used in the first vaccines. Recently there has been an increase in reports of respiratory disease associated with BoCV infections. Comparison of the recent BoCV strains to the vaccine strains revealed that they were different. The purpose of this study was to determine if the more recent strains caused a different disease than the older BoCV strains. It was found that infection of calves with the newer strains did not result in clinical disease. This suggests that the respiratory disease observed in the field was the result of concurrent infection with BoCV and another pathogen. Future studies will focus on dual infections with BoCV and bovine viral diarrhea viruses.