Rippy M K, Topper M J, Mebus C A, Morrill J C
Pathology Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD.
Vet Pathol. 1992 Nov;29(6):495-502. doi: 10.1177/030098589202900602.
Three calves (Nos. 1, 2 = 7 days old; No. 3 = 21 days old) were inoculated subcutaneously with virulent Rift Valley fever (RVF) virus. All calves became viremic and clinically ill, but the two 7-day-old calves were moribund and were euthanatized subsequently on post-inoculation day (PID) 3. Highest viral titers were measured in the serum, with lesser concentrations in the brain, heart, spleen, and liver of these animals. Viral antigens were detected by immunohistochemical analysis only in the livers, where positive staining was localized in coalescing foci of hepatocellular necrosis. The 21-day-old calf appeared to recover after viremia and pyrexia but became lethargic and ataxic and was euthanatized on PID 9. The calf was no longer viremic, and RVF virus was isolated only from the brain. Microscopic examination of the central nervous system revealed diffuse perivascular infiltrates of lymphocytes and macrophages, multifocal meningitis, and focal areas of neuronal necrosis and aggregates of macrophages, lymphocytes, and neutrophils throughout all regions of the brain and cervical spinal cord. There was positive immunohistochemical staining for viral antigens within the cytoplasm of neurons and glial cells throughout the central nervous system. Thus, RVF virus can cause encephalomyelitis in calves, and the specific virologic diagnosis can be made by immunohistochemical localization of viral antigens in formalin-fixed tissues.
三头犊牛（编号1、2，7日龄；编号3，21日龄）经皮下接种了强毒性裂谷热（RVF）病毒。所有犊牛均出现病毒血症并出现临床病症，但两头7日龄的犊牛濒死，随后在接种后第3天实施了安乐死。在这些动物的血清中测得最高病毒滴度，而在脑、心脏、脾脏和肝脏中的浓度较低。仅在肝脏中通过免疫组织化学分析检测到病毒抗原，阳性染色定位于肝细胞坏死的融合病灶中。这头21日龄的犊牛在病毒血症和发热后似乎有所恢复，但随后变得嗜睡和共济失调，并在接种后第9天实施了安乐死。这头犊牛不再有病毒血症，仅从脑中分离出裂谷热病毒。对中枢神经系统的显微镜检查显示，淋巴细胞和巨噬细胞呈弥漫性血管周围浸润、多灶性脑膜炎，以及在脑和颈脊髓的所有区域均有神经元坏死灶和巨噬细胞、淋巴细胞及中性粒细胞聚集。在整个中枢神经系统的神经元和神经胶质细胞胞质内，病毒抗原免疫组织化学染色呈阳性。因此，裂谷热病毒可在犊牛中引起脑脊髓炎，并且可通过对福尔马林固定组织中的病毒抗原进行免疫组织化学定位来做出特异性病毒学诊断。
