Studies on age-dependent resistance of mice to hemagglutinating encephalomyelitis virus infection

研究了小鼠对血凝性脑脊髓炎病毒（HEV）致死性感染的年龄依赖性抵抗力。戊型肝炎病毒MB-67 N株可引起急性致死性中枢神经系统感染。该病毒具有嗜神经性，可在大脑皮层神经细胞和小脑浦肯野细胞等中枢神经系统内增殖。在鼻内感染中，病毒从病毒复制的主要部位经趋化神经传播到中枢神经系统。虽然成年鼠和新生鼠的感染过程无明显差别，但新生鼠对致死性脑脊髓炎的抵抗力具有年龄依赖性，新生鼠的抵抗力随年龄增长而递增，且脑内感染的年龄依赖性较感染更为显著。成年小鼠的抗性受小鼠遗传背景的影响，但在免疫缺陷（T-、B-和NK-缺陷）和免疫抑制（泼尼松龙和环磷酰胺处理）小鼠中不降低。提示小鼠对致死性戊型肝炎病毒感染的年龄依赖性抵抗力与病毒从外周向中枢传播过程中免疫功能的成熟无关，而与病毒在中枢神经系统神经细胞上的复制有关。与年龄依赖性抵抗有关的因素可能是中枢神经系统干扰素的产生或大脑皮层神经细胞的分化成熟。

The age-dependent resistance of mice to fatal infection with hemagglutinating encephalomyelitis virus (HEV) was investigated. MB-67N strain of HEV caused acute fatal infection of central nervous system(CNS). This virus had neurotropism, and propagated in CNS such as nerve cells of cerebral cortex and Purkinje's cells in cerebellum. In intranasal(in) infection, it was suggested that the virus spread from primary sites of viral replication via offactory nerve to the CNS. Although there was no difference between these infectious process of adult and newborn, age-dependent resistance to fatal encephalomyelitis was found. The resistance of newborn mice was increased progressively accompanied with age, and of age-dependency was more remarkable in intracerebral(ic) than in infection. The resistance in adult mice was influenced with genetic background of mice, but not reduced in immunodeficient (T-, B-, and NK-deficient) and immunosuppressive (prednisolone- and cyclophosphamide-treated)mice. It was suggested that the age-dependent resistance of mice to fatal HEV infection had little relation with maturation of immunological function in viral spread from peripheral site to CNS, but influenced with viral replication on nerve cells in CNS. The factors rented with age-dependent resistance may be production of the interferon in CNS or differentiation and maturation of nerve cells in cerebral cortex.