Baker J C, Rust S R, Walker R D
Department of Large Animal Clinical Sciences, College of Agriculture, Michigan State University, East Lansing 48824-1314.
Am J Vet Res. 1989 Jun;50(6):814-6.
Ninety-seven feeder steers, averaging 7 months of age, were allotted to 3 groups. Group I (n = 33) was vaccinated intranasally with an infectious bovine rhinotracheitis virus (IBRV) vaccine on postinoculation day (PID) 0; group II (n = 31) was not vaccinated on PID 0 but was commingled with group I; and group III (n = 33) served as controls housed in the same facility, but was physically separated from groups I and II. On PID 20, all steers were given a modified-live IBRV vaccine IM. Virus isolation attempts from nasal swab specimens collected on PID 10 resulted in IBRV isolation from 19 (57.6%) of group I, 4 (12.9%) of group II, and 0 of group III. By PID 20, geometric mean titer for serum antibody to IBRV had increased in group I but had decreased in groups II and III. By PID 40, geometric mean titer for serum antibody to IBRV had increased in the 3 groups in response to IM vaccination given on PID 20. Seemingly, transmission of a vaccinal strain of IBRV to nonvaccinated steers did not take place at a frequency that elicited a humoral immune response similar to that of vaccinated steers.
97头平均7月龄的育肥牛被分配到3组。第I组（n = 33）在接种后第0天（PID 0）经鼻接种传染性牛鼻气管炎病毒（IBRV）疫苗；第II组（n = 31）在PID 0未接种疫苗，但与第I组混养；第III组（n = 33）作为对照组，饲养在同一设施中，但与第I组和第II组物理隔离。在PID 20时，所有育肥牛均肌肉注射改良活IBRV疫苗。对PID 10采集的鼻拭子样本进行病毒分离，结果在第I组19头（57.6%）、第II组4头（12.9%）中分离到IBRV，第III组未分离到。到PID 20时，第I组血清中抗IBRV抗体的几何平均滴度升高，而第II组和第III组则下降。到PID 40时，由于在PID 20时进行了肌肉注射疫苗，3组血清中抗IBRV抗体的几何平均滴度均升高。似乎，IBRV疫苗株向未接种疫苗的育肥牛的传播频率并未引发与接种疫苗的育肥牛相似的体液免疫反应。
