Montgomery D L, Van Olphen A, Van Campen H, Hansen T R
Department of Veterinary Sciences, University of Wyoming, Laramie, WY, USA.
Vet Pathol. 2008 May;45(3):288-96. doi: 10.1354/vp.45-3-288.
Previous studies have shown that the brain is a target of persistent infection with bovine viral diarrhea virus (BVDV) and have demonstrated viral tropism for neurons as well as other endogenous cell types in diverse brain areas. Apart from foci of mild residual inflammation in some postnatal calves, consistent brain lesions, per se, have not been reported. No similar comprehensive studies of the brain have been reported in bovine fetuses. In the current study, 12 BVDV-seronegative heifers were inoculated intranasally with a 2-ml 4.4 log(10) TCID(50)/ml dose of noncytopathic type 2 BVDV at 75 and 175 days of gestation to create persistently and transiently infected fetuses, respectively. In only persistently infected fetuses, encephaloclastic lesions resulting in pseudocysts were observed in the subependymal zone in the region of the median eminence and adjacent corona radiata as well as in the region of the external capsule associated with lenticulostriate arteries. Additionally, areas of rarefaction in white matter were observed at the tips of cerebrocortical gyri and in the external capsule. The distribution of viral antigen was examined by immunohistochemical labeling using the 15C5 anti-BVDV monoclonal antibody. Viral antigen was detected only in calves inoculated at 75 days of gestation, i.e., persistently infected. The pattern of BVDV immunolabeling revealed both similarities and differences compared with previous studies in postnatal calves, suggesting that viral infection in the brain is a dynamic and progressive rather than static process.
先前的研究表明，大脑是牛病毒性腹泻病毒（BVDV）持续感染的靶器官，并且已证明该病毒对不同脑区的神经元以及其他内源性细胞类型具有嗜性。除了一些出生后小牛存在轻度残留炎症病灶外，尚未有一致的脑部病变的报道。在牛胎儿中，尚未有类似的关于大脑的全面研究报道。在本研究中，12头BVDV血清阴性的小母牛在妊娠75天和175天时分别经鼻接种2 ml剂量为4.4 log(10) TCID(50)/ml的非细胞病变型2型BVDV，以分别产生持续感染和短暂感染的胎儿。仅在持续感染的胎儿中，在正中隆起区域及相邻的放射冠的室管膜下区以及与豆纹动脉相关的外囊区域观察到导致假囊肿形成的脑破坏性病变。此外，在脑皮质回的尖端和外囊中观察到白质稀疏区域。使用15C5抗BVDV单克隆抗体通过免疫组织化学标记检查病毒抗原的分布。仅在妊娠75天时接种的小牛（即持续感染的小牛）中检测到病毒抗原。与先前对出生后小牛的研究相比，BVDV免疫标记模式显示出异同，这表明大脑中的病毒感染是一个动态且渐进的过程，而非静态过程。
