乙型脑炎病毒持续感染株在不同条件下病毒量的变化及分析

目的研究乙脑病毒持续感染株在不同条件下病毒量的变化及探讨影响病毒增殖的因素。方法乙脑病毒野生株JaGAr-01株和Nakayama株分别感染人肝癌细胞株KN73，建立乙脑病毒持续感染模型。采用空泡斑点实验进行病毒滴度测定。用持续感染病毒感染人神经纤维母细胞瘤细胞株IMR．32，在30℃和37℃下检测病毒的温度感受性；分别将两种野生株感染持续感染了病毒的KN73细胞，进行病毒重复感染实验；为探讨持续感染病毒的增殖性，将其感染KN73细胞和IMR．32细胞。结果两种持续感染病毒的增殖量均无温度差异性。重复感染实验结果：JaGAr-01株的病毒量是对照的1．3％和8．8％；Nakayama株的病毒量是对照的80．0％和1．7％。两种野生株及其持续感染株分别感染KN73和IMR．32细胞，前者中两种持续感染株的增殖性比野生株明显低下，而在后者中两株的增殖性与其野生株相近。结论两种持续感染的乙脑病毒均无温度变异株；乙脑病毒的持续感染系中可能存在含有DI粒子的变异病毒；在不同细胞中宿主因子对阻碍持续感染株的增殖存在差异。

Analysis of change in viral titers under different conditions in cultured cells persistently-infected with Japanese encephalitis virus

OBJECTIVE: To investigate the change of viral titers under different conditions in cultured cells persistently-infected with different strains of Japanese encephalitis virus (JEV) and find out the factors that influence viral multiplication. METHODS: JEV JaGAr-01 and Nakayama wild strains were used to infect human hepatoma cell line KN73 respectively, and the persistent infection model was established. Viral titers were examined by plaque methods using BHK cells. Human nerve fibroblastoma cell line IMR-32 was infected with the strains of the virus that can cause persistent infection, and the thermal sensitivity of the viral strains was measured at 30 degrees C and 37 degrees C. KN73 cells persistently infected with JEV were infected with two JEV strains respectively, and viral superinfection was studied. To explore the replication of the persistently-infected viruses, KN73 and IMR-32 cells were infected with the viral strains. RESULTS: Two persistently infected viral strains did not show any thermal difference. The results of superinfection were that the viral titers of JaGAr-01 strains were 1.3 and 8.8 percent of the control, respectively, and the viral titers of Nakayama strain were 80 and 1.7 percent of the control, respectively. JaGAr-01 wild strains, Nakayama wild strains and their persistently-infected strains infected KN73 and IMR-32 respectively. The replication of the persistently-infected strains was obviously lower than the wild strains in KN73 cells, however, in IMR-32 cells their replication was similar. CONCLUSIONS: The two strains of JEV were not found to be temperature-mutant. It is possible that mutant viruses containing DI particles exist in JEV persistently-infected strains. In different cells there may be different host factors hindering the replication of the persistently-infected strains.