Laboratory of Vector Capacity, Institute of Infectology, Friedrich-Loeffler-Institut, Greifswald, Germany.
Institute for Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut, Greifswald, Germany.
Zoonoses Public Health. 2020 Jun;67(4):416-424. doi: 10.1111/zph.12700. Epub 2020 Mar 12.
West Nile virus (WNV), a zoonotic arbovirus, has recently established an autochthonous transmission cycle in Germany. In dead-end hosts like humans and horses the WNV infection may cause severe symptoms in the central nervous system. In nature, WNV is maintained in an enzootic transmission cycle between birds and ornithophilic mosquitoes. Bridge vector species, such as members of the Culex pipiens complex and Aedes spp., also widely distributed in Germany, might transmit WNV to other vertebrate host species. This study determined and compared the vector competence of field-collected northern-German Cx. pipiens biotype pipiens and laboratory-reared Ae. vexans Green River (GR) for WNV lineage 1 (strain: Magpie/Italy/203204) and WNV lineage 2 (strain: "Austria") under temperatures typical for northern Germany in spring/summer and autumn. For assessment of vector competence, 7- to 14-day-old female mosquitoes were offered a WNV containing blood meal via Hemotek membrane feeding system or cotton-stick feeding. After incubation at 18°C respectively 24°C for 14 days engorged female mosquitoes were salivated and dissected for determination of infection, dissemination and transmission rates by reverse transcriptase quantitative real-time PCR (RT-qPCR). Both Ae. vexans GR and Cx. pipiens biotype pipiens were infected with both tested WNV strains and tested 14 days post-inoculation. Disseminated infections were detected only in Ae. vexans GR incubated at 18°C and in Cx. pipiens pipiens incubated at 24°C after infection with WNV lineage 1. Transmission of WNV lineage 1 was detected in Cx. pipiens pipiens incubated at 24°C. These results indicate that Cx. pipiens pipiens from Northern Germany may be involved in the transmission of WNV, also to dead-end hosts like humans and horses.
西尼罗河病毒（WNV）是一种人畜共患的虫媒病毒，最近在德国建立了一个本地传播周期。在人类和马等末端宿主中，WNV 感染可能导致中枢神经系统严重症状。在自然界中，WNV 在鸟类和嗜鸟蚊之间维持着地方性传播循环。桥梁媒介物种，如库蚊复合体和伊蚊属的成员，也广泛分布在德国，可能会将 WNV 传播给其他脊椎动物宿主。本研究确定并比较了野外采集的德国北部库蚊生物型 pipiens 和实验室饲养的 Aedes vexans 绿河（GR）对 WNV 谱系 1（株：喜鹊/意大利/203204）和 WNV 谱系 2（株：“奥地利”）的媒介能力，这些温度是德国北部春季/夏季和秋季的典型温度。为了评估媒介能力，7-14 日龄的雌性蚊子通过 Hemotek 膜喂养系统或棉花棒喂养接受含有 WNV 的血餐。在 18°C 或 24°C 孵育 14 天后，饱血的雌性蚊子被唾液分泌并解剖，通过逆转录定量实时 PCR（RT-qPCR）测定感染、传播和传播率。Ae. vexans GR 和 Cx. pipiens biotype pipiens 均感染了两种测试的 WNV 株，并在接种后 14 天进行了测试。仅在感染 WNV 谱系 1 时在 18°C 孵育的 Ae. vexans GR 和在 24°C 孵育的 Cx. pipiens biotype pipiens 中检测到传播感染。WNV 谱系 1 的传播在 24°C 孵育的 Cx. pipiens biotype pipiens 中被检测到。这些结果表明，来自德国北部的库蚊可能参与了 WNV 的传播，也可能传播给人类和马等末端宿主。
