Interferon, fluorescent antibody, and neutralizing antibody responses in sera of calves inoculated with bovine respiratory syncytial virus
El-Azhary, M.A.; Silim, A.; Roy, R.S.
American Journal of Veterinary Research 42(8): 1378-1382
1981
ISSN/ISBN: 0002-9645 PMID: 6170241 Document Number: 177925
Interferon, fluorescent antibody and neutralizing antibody responses were studied in sera of 9 calves inoculated with bovine respiratory syncytial virus, in relation to viral shedding and clinical signs of disease. The calves (5.5-6.5 wk old) were assigned to 3 groups. Group 1 was inoculated once with the virus and groups 2 and 3 were challenge exposed at postinoculation day (PID) 15 or 37. Serum-neutralizing and indirect fluorescent antibody techniques were used to measure antibody responses. The plaque-inhibition technique, using vesicular stomatitis virus, was applied to measure serum interferon titers. The virus was recovered by inoculation of nasal secretions onto cell [secondary bovine fetal skin and Madin-Darby bovine kidney] cultures. Fluorescent antibody was detected in all calves on PID 3 with maximum titers appearing approximately on PID 10. Low neutralizing antibody was detected in most animals on PID 3; titers peaked .apprx. 4.5 wk after inoculation and then decreased. Interferon titers were high in all calves during the early stage of infection, dropped to undetectable amounts by PID 6 and reappeared in low amounts at least 1 wk later. All infected calves manifested clinical signs of disease by PID 4-9. Clinical signs of disease were not observed after challenge exposure at PID 15 or 37 and anamnestic responses were not detected. Virus was recovered after challenge enposure at PID 15 but not at PID 37.