Mlera Luwanika, Melik Wessam, Offerdahl Danielle K, Dahlstrom Eric, Porcella Stephen F, Bloom Marshall E
Biology of Vector-Borne Viruses Section, Laboratory of Virology, National Institutes of Health, Hamilton, MT 59840, USA.
Genomics Unit, Research Technologies Branch, Hamilton, MT 59840, USA.
Viruses. 2016 Sep 10;8(9):252. doi: 10.3390/v8090252.
Tick-borne flaviviruses (TBFVs) cause a broad spectrum of disease manifestations ranging from asymptomatic to mild febrile illness and life threatening encephalitis. These single-stranded positive-sense (ss(+)) RNA viruses are naturally maintained in a persistent infection of ixodid ticks and small-medium sized mammals. The development of cell lines from the ixodid ticks has provided a valuable surrogate system for studying the biology of TBFVs in vitro. When we infected ISE6 cells, an Ixodes scapularis embryonic cell line, with Langat virus (LGTV) we observed that the infection proceeded directly into persistence without any cytopathic effect. Analysis of the viral genome at selected time points showed that no defective genomes were generated during LGTV persistence by 10 weeks of cell passage. This was in contrast to LGTV persistence in 293T cells in which defective viral genomes are detectable by five weeks of serial cell passage. We identified two synonymous nucleotide changes i.e., 1893A→C (29% of 5978 reads at 12 h post infection (hpi)) and 2284T→A (34% of 4191 reads at 12 hpi) in the region encoding for the viral protein E. These results suggested that the mechanisms supporting LGTV persistence are different between tick and mammalian cells.
蜱传黄病毒（TBFVs）可引发广泛的疾病表现，从无症状感染到轻度发热性疾病以及危及生命的脑炎。这些单链正链（ss(+)）RNA病毒在硬蜱和中小型哺乳动物的持续感染中自然维持。从硬蜱建立细胞系为体外研究TBFVs的生物学特性提供了一个有价值的替代系统。当我们用兰加特病毒（LGTV）感染肩突硬蜱胚胎细胞系ISE6细胞时，我们观察到感染直接进入持续状态，没有任何细胞病变效应。在选定时间点对病毒基因组进行分析表明，在细胞传代10周的LGTV持续感染期间未产生缺陷基因组。这与LGTV在293T细胞中的持续感染情况形成对比，在293T细胞中，连续传代5周后可检测到缺陷病毒基因组。我们在编码病毒蛋白E的区域鉴定出两个同义核苷酸变化，即1893A→C（感染后12小时（hpi）时5978条读数中的29%）和2284T→A（感染后12小时时4191条读数中的34%）。这些结果表明，蜱细胞和哺乳动物细胞中支持LGTV持续感染的机制不同。
