Evaluation of the safety and efficacy of an intranasal vaccine containing a temperature-sensitive strain of infectious bovine rhinotracheitis virus
Kucera, C.J.; White, R.G.; Beckenhauer, W.H.
American Journal of Veterinary Research 39(4): 607-610
1978
ISSN/ISBN: 0002-9645 PMID: 206171 Document Number: 133544
Three tests were conducted to evaluate the safety and efficacy of an intranasal infectious bovine rhinotracheitis (IBR) vaccine containing a modified live temperature-sensitive virus strain capable of replicating in the nasal mucosa, but not in the warmer internal body regions. In a test of safety and immunogenicity, 268 seronegative feedlot calves in 3 herds were vaccinated and evaluated serologically and clinically. Vaccinated calves had an overall seroconversion rate of 82.8%, with results ranging between 71.1-100% among the 3 test herds. The overall seroconversion rate in 132 seronegative control (nonvaccinated) calves was 40.9%. All calves remained clinically normal following vaccination. In a challenge-of-immunity test, 21 seronegative calves were vaccinated and challenge exposed 4 wk later. All but 1 of the vaccinated calves remained normal; the 5 control calves developed signs of IBR. Before challenge exposure, seroconversion occurred in all vaccinated calves except the 1 affected. The vaccine was administered to 1019 pregnant cows in 12 herds to determine if it had abortigenic properties. Post-vaccination reactions were not observed in the vaccinated cows or in 510 pregnant control (nonvaccinated) cows in the same herds. Of the seronegative cows, 89.2% of the vaccinated cows and 23.6% of the controls had postvaccination serum antibody titers. Abortions occurred in 3 vaccinated cows and 1 control cow, all having had prevaccination titers for IBR. Laboratory evaluations of the aborted fetuses were negative for IBR virus.