Lebanese University, Faculty of Public Health-II, Laboratory of Immunology and Vector Borne Diseases, Fanar, Lebanon.
Institut Pasteur, Department of Virology, Arboviruses and Insect Vectors, Paris cedex 15, France.
PLoS Negl Trop Dis. 2018 Jan 11;12(1):e0005983. doi: 10.1371/journal.pntd.0005983. eCollection 2018 Jan.
West Nile virus (WNV) and Rift Valley fever virus (RVFV) are two emerging arboviruses transmitted by Culex pipiens species that includes two biotypes: pipiens and molestus. In Lebanon, human cases caused by WNV and RVFV have never been reported. However, the introduction of these viruses in the country is likely to occur through the migratory birds and animal trades. In this study, we evaluated the ability of Cx. pipiens, a predominant mosquito species in urban and rural regions in Lebanon, to transmit WNV and RVFV. Culex egg rafts were collected in the West Bekaa district, east of Lebanon and adult females of Cx. pipiens were experimentally infected with WNV and RVFV Clone 13 strain at titers of 1.6×108 and 1.33×107 plaque forming units (PFU)/mL, respectively. We estimated viral infection, dissemination and transmission at 3, 7, 14 and 19 days post infection (dpi). Results showed that infection was higher for WNV than for RVFV from 3 dpi to 19 dpi. Viral dissemination and transmission started from 3 dpi for WNV; and only from 19 dpi for RVFV. Moreover, Cx. pipiens were able to excrete in saliva a higher number of viral particles of WNV (1028 ± 405 PFU/saliva at 19 dpi) than RVFV (42 PFU/saliva at 19 dpi). Cx. pipiens from Lebanon are efficient experimental vectors of WNV and to a lower extent, RVFV. These findings should stimulate local authorities to establish an active entomological surveillance in addition to animal surveys for both viruses in the country.
西尼罗河病毒（WNV）和裂谷热病毒（RVFV）是两种通过库蚊属的两种生物型（pipiens 和 molestus）传播的新兴虫媒病毒。在黎巴嫩，从未报告过人感染 WNV 和 RVFV 的病例。然而，这些病毒很可能通过候鸟和动物贸易传入该国。在这项研究中，我们评估了黎巴嫩城乡地区主要蚊种库蚊属对 WNV 和 RVFV 的传播能力。在黎巴嫩东部的贝卡西部地区收集了库蚊属卵筏，并以 1.6×108 和 1.33×107 噬菌斑形成单位（PFU）/mL 的滴度对感染了 WNV 和 RVFV Clone 13 株的雌性成年库蚊进行了实验性感染。我们在感染后 3、7、14 和 19 天估计了病毒感染、传播和传播。结果表明，从 3 天到 19 天，WNV 的感染率高于 RVFV。WNV 的病毒传播和传播从 3 天开始；而 RVFV 仅从 19 天开始。此外，库蚊属在 19 天的唾液中能排出更多的 WNV 病毒颗粒（1028±405PFU/唾液），而 RVFV 仅能排出 42PFU/唾液。黎巴嫩的库蚊属是 WNV 的高效实验性载体，而对 RVFV 的传播效率则较低。这些发现应该促使地方当局在该国建立针对这两种病毒的积极昆虫学监测和动物调查。
