Bluetongue virus (BTV) is an arbovirus that has been associated with dramatic epizootics in both wild and domestic ruminants in recent decades. As a segmented, double-stranded RNA virus, BTV can evolve via several mechanisms due to its genomic structure. However, the effect of BTV’s alternating-host transmission cycle on the virus’s genetic diversification remains poorly understood. Whole genome sequencing approaches offer a platform for investigating the effect of host-alternation across all ten segments of BTV’s genome. To understand the role of alternating hosts in BTV’s genetic diversification, a field isolate was passaged under three different conditions: (i) serial passages in Culicoides sonorensis cells, (ii) serial passages in bovine pulmonary artery endothelial cells, or (iii) alternating passages between insect and bovine cells. Aliquots of virus were sequenced, and single nucleotide variants were identified. Measures of viral population genetics were used to quantify the genetic diversification that occurred. Two consensus variants in segments 5 and 10 occurred in virus from all three conditions. While variants arose across all passages, measures of genetic diversity remained largely similar across cell culture conditions. Despite passage in a relaxed in vitro system, we found that this BTV isolate exhibited genetic stability across passages and conditions. Our findings underscore the valuable role that whole genome sequencing may play in improving understanding of viral evolution and highlight the genetic stability of BTV.

中文翻译：

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单个蓝舌病病毒株的遗传多样性使用交替宿主传播的体外模型。

蓝舌病病毒（BTV）是一种虫媒病毒，最近几十年来，它与野生和家养反刍动物中的严重动物流行病有关。BTV作为一种分段的双链RNA病毒，由于其基因组结构，可以通过多种机制进化。但是，BTV的交替宿主传播周期对病毒遗传多样性的影响仍然知之甚少。全基因组测序方法提供了一个平台，用于研究BTV基因组的所有十个部分的宿主交替效应。为了了解交替宿主在BTV遗传多样性中的作用，在三种不同条件下对田间分离株进行传代：（i）Culicoides sonorensis中的连续传代细胞；（ii）牛肺动脉内皮细胞的连续传代，或（iii）昆虫和牛细胞之间的交替传代。对病毒等分试样进行测序，并鉴定出单核苷酸变体。病毒种群遗传学的测量方法用于量化发生的遗传多样性。在这三种情况下，病毒的片段5和10中都有两个共有变体。尽管在所有传代中都出现了变体，但是在细胞培养条件下，遗传多样性的度量仍然非常相似。尽管在轻松的体外系统中传代，我们发现该BTV分离物在传代和条件间均表现出遗传稳定性。我们的发现强调了全基因组测序在增进对病毒进化的理解中可能发挥的宝贵作用，并强调了BTV的遗传稳定性。