Vector competence of British mosquitoes to flaviviruses

英国蚊子能把病毒传染给牲畜和人吗？英国蚊子是否能够传播节肢动物传播的病毒（“虫媒病毒”），这一点存在很大的不确定性。一方面，英国有一些蚊子物种与欧洲大陆的虫媒病毒传播有关，其中一些地方的气候和环境与英国相似。另一方面，蚊子传播的病毒在英国还没有传播过（除了少数通过昆虫的口器“机械”传播）。此外，据报道，蚊子对不同病毒的能力存在区域差异。因此，英国是否有合适的蚊子但传播病毒的条件不合适，我们的蚊子是否根本不能传播病毒，或者我们的蚊子是否有能力传播病毒，但机会还没有出现，这一点还不清楚。鉴于全球变化对传染病出现的影响，至关重要的是，联合王国的病媒进行评估，其潜在的传播虫媒病毒，以便安装知情的缓解程序之前，或在发生疫情。此外，蚊子传播虫媒病毒的能力对温度敏感，这使得此类病毒可能受到气候变化的影响;为了评估未来的风险，了解温度的影响是很重要的。我们的主要目的是确定英国本土蚊子和英国的入侵蚊子物种是否会被感染并传播影响牲畜和人类的病毒，以及这种能力如何，如果存在，则受温度影响。欧洲报告了10种蚊媒虫媒病毒，其中一些与英国纬度相似。实地观察表明，潜在的本地载体，特别是西尼罗河病毒（WNV）载体，是目前在英国。2011年，发现西尼罗河病毒的主要传播媒介--虽然这些蚊子的存在本身就表明存在虫媒病毒传播的风险，但必须在详细的实验室实验中证明这些蚊子作为媒介的潜力，因为这些蚊子传播这些病毒的能力存在遗传和环境变异。虽然几种蚊媒病毒的出现是合理的，但我们选择了日本脑炎病毒（JEV）和WNV在英国蚊子中进行评估。选择JEV进行这项研究是因为我们已经感染了来自英国的一种蚊子Ochlerotatus detritus，并发现这种蚊子能够传播JEV。虽然JEV主要发生在亚洲大陆，但虫媒病毒的洲际传入确实发生，并且随着人类流动性的增加，可能变得更加普遍。事实上，JEV的证据最近已经在欧洲蚊子中报道。西尼罗河病毒被选中进行这项研究，因为它可以说是对英国构成最紧迫的威胁。西尼罗河病毒广泛分布于地球仪，在非洲、中亚西部、中东、欧洲和最近的北美都有发现。该病毒感染了多种蚊子和脊椎动物宿主。由于它在北美和欧洲，特别是法国南部的传播，以及它在欧洲其他地方与英国相似的纬度发生，这种病毒是英国的主要利益。我们将使用一种感染模型，在该模型中，来自野外的蚊子将直接感染最近分离的病毒株。将对蚊子进行评估：它们传播病毒的能力;实现感染所需的病毒剂量;以及温度对其媒介能力的影响。

Are British mosquitoes capable of transmitting viruses to livestock and people? There is great uncertainty whether British mosquitoes are capable of transmitting arthropod-borne viruses ("arboviruses"). On one hand, the UK has some mosquito species that are implicated in the transmission of arboviruses in mainland Europe, and the climate and environment in some of these locations are similar to those in the UK. On the other hand, mosquito-borne viruses are not known to have been transmitted in the UK (apart from a small number that are 'mechanically' transmitted on the insects' mouthparts). Furthermore, regional differences in competence of mosquitoes to different viruses have been reported. Therefore, it is not clear whether the UK has the right mosquitoes but the wrong conditions for virus transmission; whether our mosquitoes simply cannot transmit viruses; or whether our mosquitoes are capable of transmitting viruses, but the opportunity has not yet arisen. Given the impact of global change on the emergence of infectious diseases, it is paramount that UK vectors are assessed for their potential to transmit arboviruses, in order to mount informed mitigation procedures in advance of, or in the event of, an outbreak. Furthermore, the ability of mosquitoes to spread arboviruses is sensitive to temperature, making such viruses likely to be affected by climate change; it is important to understand the effects of temperature in order to assess future risks.Our main aim here is to determine whether native British mosquitoes and invasive mosquito species present in the UK can be infected and transmit viruses that affect livestock and humans, and how this ability, if present, is affected by temperature. Ten mosquito-borne arboviruses have been reported in Europe with some at similar latitude to the UK. Field observations have shown potential native vectors, particularly West Nile virus (WNV) vectors, to be present in the UK. In 2011, Culex modestus, a major vector of WNV, was found actively propagating in the UK, representing the first known introduction and establishment of an invasive mosquito species. While the mere presence of these mosquitoes suggests a risk for arbovirus transmission, further support for the potential of these mosquitoes to serve as vectors must be demonstrated in detailed laboratory experiments since there is genetic and environmental variation in the ability of these mosquitoes to transmit these viruses. While the emergence(s) of several mosquito-borne viruses is plausible, we have chosen Japanese encephalitis virus (JEV) and WNV for evaluation in UK mosquitoes. JEV was selected for this study because we have already infected Ochlerotatus detritus, a mosquito from the UK, and found this mosquito able to transmit JEV. Though JEV occurs mostly on the Asian continent inter-continental introductions of arboviruses do occur, and with increased human mobility, may become more common. In fact, evidence for JEV has recently been reported in European mosquitoes. WNV was selected for this study because it arguably poses the most imminent threat to UK. WNV is widely distributed across the globe, being found in Africa, West Central Asia, the Middle East, Europe and recently North America. The virus infects a wide range of mosquitoes and vertebrate hosts. Due to its spread in North America and in Europe, particularly southern France, and its occurrence in similar latitudes to the UK elsewhere in Europe, this virus is of major interest to the UK. We will use an infection model where mosquitoes from the field will be directly infected with recently isolated strains of viruses. Mosquitoes will be assessed for: their ability to transmit virus; the viral dosage required to achieve infection; and the effect of temperature on their vector competence.