Lloyd R E, Bovee M
Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City 73190.
Virology. 1993 May;194(1):200-9. doi: 10.1006/viro.1993.1250.
Human erythroblastoid K562 cells have been recently described as a relatively nonpermissive host for poliovirus replication. During investigations of virus-induced cytopathic effects in this cell line, we discovered that poliovirus easily established persistently infected cultures in K562-Mu cells. In these cultures, most cells remained viable, with overall viability continuously maintained between 67 and 92% over 3 months. Infected K562 cells continued to grow, usually without any major periods of crisis in the culture or large diminutions in cell growth rate. K562-Mu cells produced a slower onset of virus production than observed in HeLa cells, and virus titers in culture supernates rapidly stabilized at levels between 10(5) and 10(6) PFU/ml. In infectious center or limiting dilution assays, only about 10% of K562 cells produced infectious virus after 2 days. However, when assays were extended to 3 to 5 days, most K562 cells in the culture scored as infectious centers, suggesting productive infection of all cells in the culture with delayed kinetics of virus production. Cultures of infected K562 cells could not be cured of virus by prolonged incubation with high-titer neutralizing antibody. Pulse-label SDS-PAGE analysis of infected cultures detected moderate levels of virus protein synthesis which peaked at 9-12 hr postinfection; however, little or no shutoff of host protein synthesis was observed at any time point during infection. Immunoblot analysis with antisera to the p220 subunit of eIF-4F demonstrated extensive but incomplete cleavage of p220 in infected K562 cells at times which correlated with peak viral protein synthesis. Taken together, the results demonstrate a persistent infection in which host cell shutoff does not occur despite significant viral protein synthesis and extensive early degradation of p220.
人成红细胞样K562细胞最近被描述为脊髓灰质炎病毒复制的相对非允许性宿主。在对该细胞系中病毒诱导的细胞病变效应进行研究期间，我们发现脊髓灰质炎病毒很容易在K562-Mu细胞中建立持续感染的培养物。在这些培养物中，大多数细胞保持存活，在3个月内总体活力持续维持在67%至92%之间。被感染的K562细胞继续生长，通常在培养过程中没有任何重大危机期或细胞生长速率大幅下降。K562-Mu细胞产生病毒的起始速度比在HeLa细胞中观察到的要慢，培养上清液中的病毒滴度迅速稳定在10⁵至10⁶ PFU/ml之间。在感染中心或有限稀释试验中，2天后只有约10%的K562细胞产生感染性病毒。然而，当试验延长至3至5天时，培养物中的大多数K562细胞被计为感染中心，这表明培养物中的所有细胞都发生了生产性感染，但病毒产生的动力学延迟。用高滴度中和抗体长时间孵育不能使被感染的K562细胞培养物清除病毒。对感染培养物进行脉冲标记SDS-PAGE分析，检测到中等水平的病毒蛋白合成，在感染后9至12小时达到峰值；然而，在感染期间的任何时间点都未观察到宿主蛋白合成的明显关闭。用针对eIF-4F的p220亚基的抗血清进行免疫印迹分析表明，在感染的K562细胞中，p220在与病毒蛋白合成峰值相关的时间发生了广泛但不完全的裂解。综上所述，结果表明存在一种持续感染，尽管有大量病毒蛋白合成和p220的广泛早期降解，但宿主细胞关闭并未发生。
