Murphy D G, Dimock K, Kang C Y
Department of Microbiology and Immunology, University of Ottawa, Faculty of Medicine, Ontario, Canada.
Virus Res. 1990 Apr;16(1):1-16. doi: 10.1016/0168-1702(90)90039-e.
Two lines of LLC-MK2 cells persistently infected with human parainfluenza virus 3 (HPIV-3) have been maintained in culture for approximately 3 years. Subgenomic RNAs (putative defective interfering particle genomes) were detected in virions released from both persistently infected cultures. In one of the persistently infected cell lines cyclic variation in the production of virions containing standard virus genomic-size (50S) RNA and subgenomic RNA was observed. The molar ratio of subgenomic RNA to 50S RNA ranged from less than 0.1/1 to 8.7/1. Northern blot analyses revealed that the patterns of viral mRNA synthesis in persistently infected cells from both cultures were similar to those of standard virus infected cells. Furthermore, the intracellular viral-specific proteins had electrophoretic mobilities similar to the corresponding proteins in standard virus-infected cells. Nucleotide sequence analysis of cloned M gene from virus after 29 months of persistence (147 passages) revealed only one variable conservative amino acid change in two clones analyzed from each cell line, indicating that the M protein is not likely to be involved in the maintenance of the persistent infections. The possible mechanisms by which the persistent state is maintained are discussed.
两株持续感染人副流感病毒3型（HPIV - 3）的LLC - MK2细胞系已在培养中维持了约3年。在从这两种持续感染培养物中释放的病毒粒子中检测到亚基因组RNA（推测为缺陷干扰颗粒基因组）。在其中一株持续感染的细胞系中，观察到含有标准病毒基因组大小（50S）RNA和亚基因组RNA的病毒粒子产生的周期性变化。亚基因组RNA与50S RNA的摩尔比范围从小于0.1/1到8.7/1。Northern印迹分析表明，两种培养物中持续感染细胞中的病毒mRNA合成模式与标准病毒感染细胞的相似。此外，细胞内病毒特异性蛋白的电泳迁移率与标准病毒感染细胞中的相应蛋白相似。对持续29个月（147代）后的病毒克隆M基因进行核苷酸序列分析，结果显示从每个细胞系分析的两个克隆中仅发现一个可变的保守氨基酸变化，这表明M蛋白不太可能参与维持持续感染。文中讨论了维持持续状态的可能机制。
