Tick-borne encephalitis virus (TBEV), like other arthropod-transmitted viruses, depends on specific vectors to complete its enzootic cycle. It has been long known that Ixodes ricinus ticks constitute the main vector for TBEV in Europe. In contrast to the wide distribution of the TBEV vector, the occurrence of TBEV transmission is focal and often restricted to a small parcel of land, whereas surrounding areas with seemingly similar habitat parameters are free of TBEV. Thus, the question arises which factors shape this focal distribution of TBEV in the natural habitat. To shed light on factors driving TBEV-focus formation, we used tick populations from two TBEV-foci in Lower Saxony and two TBEV-foci from Bavaria with their respective virus isolates as a showcase to analyze the impact of specific virus isolate-tick population relationships. Using artificial blood feeding and field-collected nymphal ticks as experimental means, our investigation showed that the probability of getting infected with the synonymous TBEV isolate as compared to the nonsynonymous TBEV isolate was elevated but significantly higher only in one of the four TBEV foci. More obviously, median viral RNA copy numbers were significantly higher in the synonymous virus–tick population pairings. These findings may present a hint for a coevolutionary adaptation of virus and tick populations.

中文翻译：

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TBEV环流中的稳定匹配问题：完美的壁虱病毒匹配有多重要？

与其他节肢动物传播的病毒一样，传播的脑炎病毒（TBEV）依靠特定的载体来完成其动物传播周期。早已知道蓖麻Is虫是欧洲TBEV的主要媒介。与TBEV向量的广泛分布相反，TBEV传播的发生是集中的，并且通常仅限于一小块土地，而生境参数看似相似的周围地区则没有TBEV。因此，出现了一个问题，哪些因素决定了TBEV在自然栖息地中的这一焦点分布。为了阐明驱动TBEV焦点形成的因素，我们使用了下萨克森州的两个TBEV疫源地和巴伐利亚的两个TBEV疫源地tick虱种群及其各自的病毒分离株作为展示，以分析特定病毒分离株-t虫种群关系的影响。使用人工采血和现场采集的若虫tick作为实验手段，我们的研究表明，与同义TBEV分离株相比，同义TBEV分离株感染的可能性有所提高，但仅在四个TBEV病灶之一中显着更高。更明显的是，同义病毒-ick虫种群配对中的病毒RNA拷贝数中位数显着更高。这些发现可能提示病毒和壁虱种群的共同进化适应。