Narita M, Inui S, Nanba K, Shimizu Y
Am J Vet Res. 1980 Dec;41(12):1995-9.
Recurrent infection in calves vaccinated with infectious bovine rhinotracheitis-(IBR) modified live virus was induced by dexamethasone (DM) treatment given 49 days after challenge exposure with virulent IBR virus. Nonchallenge-exposed IM and intranasally vaccinated calves did not excrete the virus after DM treatment; however, IM and intranasally vaccinated and subsequently challenge-exposed calves excreted the challenge-exposure virus into the nasal secretions 5 to 11 days and 6 to 10 days after the DM treatment, respectively. The calves were killed 15 to 18 days (experiment 1) and 14 days (experiment 2) and DM treatment was started and then were examined by histopathologic and fluorescent antibody techniques. All DM-treated calves that were inoculated with the vaccinal virus and challenge exposed with the virulent virus developed nonsuppurative trigeminal ganglionitis and encephalitis. On the contrary, the DM-treated nonchallenge-exposed vaccinated calves did not have lesions in the peripheral nervous system and CNS. Infectious bovine rhinotracheitis virus antigens were not observed in tissues of any of the calves examined (experiments 1 and 2) by fluorescent antibody techniques. These observations indicated that the modified live IBR virus neither produced lesions nor induced latent infection and that modified live IBR virus vaccination did not protect the calves against the establishment of a latent infection after their exposure to large doses of the virulent IBR virus.
用传染性牛鼻气管炎（IBR）活疫苗免疫的犊牛，在接种强毒IBR病毒49天后，用地塞米松（DM）处理可诱发反复感染。未接种强毒病毒的经肌肉注射和鼻内接种疫苗的犊牛，在DM处理后未排出病毒；然而，经肌肉注射和鼻内接种疫苗且随后接种强毒病毒的犊牛，在DM处理后分别于5至11天和6至10天，将接种的强毒病毒排至鼻分泌物中。在第15至18天（实验1）和第14天（实验2）处死犊牛，开始DM处理，然后通过组织病理学和荧光抗体技术进行检查。所有经DM处理、接种疫苗病毒并接种强毒病毒的犊牛均发生非化脓性三叉神经节炎和脑炎。相反，经DM处理、未接种强毒病毒的接种疫苗犊牛在周围神经系统和中枢神经系统未出现病变。通过荧光抗体技术，在所有检查的犊牛（实验1和2）组织中均未观察到传染性牛鼻气管炎病毒抗原。这些观察结果表明，IBR活疫苗既不产生病变也不诱导潜伏感染，并且IBR活疫苗接种不能保护犊牛在接触大剂量强毒IBR病毒后免受潜伏感染的建立。
