Comparison of vector competence of Aedes vexans Green River and Culex pipiens biotype pipiens for West Nile virus lineages 1 and 2

Abstract

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-dayold 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 postinoculation. 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. K E Y W O R D SAedes vexans, Culex pipiens pipiens, vector competence, West Nile virus | 417 WÖHNKE Et al.

Vector Competence of German Aedes punctor (Kirby, 1837) for West Nile Virus Lineages 1 and 2

“…Other studies also showed that the viremia that can be expected in WNV-infected chickens is not higher than the blood meal titers that we used [51,52]. In addition, the amount of ingested viral RNA detected in day 0 controls was not lower than in other vector competence studies where mosquito infection was successful [49,53]. Thus, the blood meal titer does not appear to be the reason of the low positivity rates.…”

Simultaneous Coinfections with West Nile Virus and Usutu Virus in Culex pipiens and Aedes vexans Mosquitoes

“…Tis indicates that our chosen blood meal titer was not decisive for this result. In a previous study, the colony "Green River" was already tested for its vector competence for WNV lineages 1 and 2 [70]. Infection rates of Ae.…”

Detection of West Nile Virus Lineage 2 in Eastern Romania and First Identification of Sindbis Virus RNA in Mosquitoes Analyzed using High-Throughput Microfluidic Real-Time PCR

“…Aedes vexans were found positive for WNV for the first time in Romania. Studies of vector competence have shown the ability of this species to transmit WNV [ 38 , 39 ]. However, its mammophilic character suggests that Aedes vexans could play only a minor role in WNV transmission, unlike the ornitophilic/generalist Culex pipiens s.l., which is the main WNV vector and was repeatedly found infected in natural and anthropic areas from the east and southeast of the country [ 40 , 41 , 42 ].…”