Since its emergence in Yap Island in 2007, Zika virus (ZIKV) has affected all continents except Europe. Despite the hundreds of cases imported to European countries from ZIKV-infested regions, no local cases have been reported in localities where the ZIKV-competent mosquito Aedes albopictus is well established. Here we analysed the vector competence of European Aedes (aegypti and albopictus) mosquitoes to different genotypes of ZIKV. We demonstrate that Ae. albopictus from France was less susceptible to the Asian ZIKV than to the African ZIKV. Critically we show that effective crossing of anatomical barriers (midgut and salivary glands) after an infectious blood meal depends on a viral load threshold to trigger: (i) viral dissemination from the midgut to infect mosquito internal organs and (ii) viral transmission from the saliva to infect a vertebrate host. A viral load in body ≥4800 viral copies triggered dissemination and ≥12,000 viral copies set out transmission. Only 27.3% and 18.2% of Ae. albopictus Montpellier mosquitoes meet respectively these two criteria. Collectively, these compelling results stress the poor ability of Ae. albopictus to sustain a local transmission of ZIKV in Europe and provide a promising tool to evaluate the risk of ZIKV transmission in future outbreaks.

中文翻译：

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寨卡病毒阈值决定了欧洲白纹伊蚊的传播。

自 2007 年在雅浦岛出现以来，寨卡病毒 (ZIKV) 已影响到除欧洲以外的所有大陆。尽管欧洲国家有数百例从寨卡病毒感染地区输入的病例，但在具有寨卡病毒能力的白纹伊蚊大量繁殖的地区尚未报告本地病例。在这里，我们分析了欧洲伊蚊（埃及伊蚊和白纹伊蚊）对不同基因型 ZIKV 的媒介能力。我们证明了 Ae. 来自法国的白纹伊蚊对亚洲寨卡病毒的敏感度低于非洲寨卡病毒。重要的是，我们表明，感染性血粉后有效穿过解剖屏障（中肠和唾液腺）取决于病毒载量阈值来触发：（i）从中肠传播病毒以感染蚊子内脏，（ii）从中肠传播病毒唾液来感染脊椎动物宿主。体内病毒载量≥4800个病毒拷贝触发传播，≥12,000个病毒拷贝引发传播。仅占 Ae 的 27.3% 和 18.2%。白纹伊蚊蒙彼利埃蚊分别满足这两个标准。总的来说，这些引人注目的结果强调了 Ae 的能力较差。白纹伊蚊可维持 ZIKV 在欧洲的本地传播，并为评估未来疫情中 ZIKV 传播的风险提供有前景的工具。