Effect of concurrent experimentally induced bovine respiratory syncytial virus and bovine viral diarrhea virus infection on respiratory tract and enteric diseases in calves
Brodersen, B.W.; Kelling, C.L.
American Journal of Veterinary Research 59(11): 1423-1430
1998
ISSN/ISBN: 0002-9645 PMID: 9829401 Document Number: 494370
Three groups of five 9- to 12-month-old calves were infected with bovine respiratory syncytial virus (BRSV), bovine diarrhoea virus (BDV) or with both viruses concurrently. Three mock-infected calves were controls. Calves with concurrent infection developed more severe clinical signs of disease (fever and diarrhoea), leukopenia and more severe lesions. They also shed virus from nasal secretions in greater concentration and for longer duration, and BRSV was isolated from their lungs. Calves with concurrent infection also had more extensive lung lesions. Alimentary epithelial necrosis and severe lymphoid depletion were associated with BDV infection in calves with or without concurrent BSV infection. BDV antigen in lymphatic tissue was detected in stromal cells only. It is concluded that concurrent infection with BRSV and BDV causes more severe respiratory tract and enteric disease than infection with either virus alone, suggesting synergistic effect between the viruses.