Vector competence of field populations of the mosquito species Aedes japonicus japonicus and Culex pipiens from Switzerland for two West Nile virus strains

• Published in: Medical and veterinary entomology 2018-03, Vol.32 (1), p.121-124
• Main Authors: WAGNER, S., MATHIS, A., SCHÖNENBERGER, A. C., BECKER, S., SCHMIDT‐CHANASIT, J., SILAGHI, C., VERONESI, E.
• Format: Article
• Language: English
• Subjects: Aedes - physiology; Aedes - virology; Aedes japonicus japonicus; Animals; Cell culture; Culex - physiology; Culex - virology; Culex pipiens; Culicidae; Diptera; Disease transmission; dissemination; Epidemics; Female; fluctuating temperature regime; Host range; Hulecoeteomyia japonica; Mosquito Vectors - physiology; Mosquito Vectors - virology; Mosquitoes; Polymerase chain reaction; Reverse transcription; Ribonucleic acid; RNA; Saliva; Species; Strains (organisms); Switzerland; transmission; Viruses; West Nile Fever - transmission; West Nile Fever - virology; West Nile virus; West Nile virus - genetics; West Nile virus - physiology
• ISSN: 0269-283X; 1365-2915
• DOI: 10.1111/mve.12273

Aedes (Hulecoeteomyia) japonicus japonicus (Diptera: Culicidae) (Theobald) is an invasive mosquito species in Central Europe, where it has colonized several areas. In this study, field‐collected specimens of Ae. japonicus and Culex pipiens (Diptera: Culicidae) (Linnaeus) from Zürich (Switzerland) were orally exposed to two strains (NY99 and FIN) of the avian zoonotic pathogen West Nile virus (WNV) (family Flaviviridae, genus Flavivirus). Dissemination and transmission of the viruses after incubation for 12–15 days under a fluctuating Central European midsummer temperature regime (24 ± 7 °C) was investigated by detection of viral RNA in homogenates of pools of both head/thorax and saliva by reverse transcription real‐time polymerase chain reaction (PCR). Culex pipiens was susceptible to WNV NY99 only, whereas both virus strains could be detected in Ae. japonicus, with the additional isolation of WNV NY99 in Vero cell culture from one saliva pool. Given the high abundances of Ae. japonicus in many newly colonized areas, its recently demonstrated broad host range, including mammalian and avian blood hosts, and its vector competence, this species is a potential key bridge vector of WNV in Central Europe. The invasive mosquito Aedes (Hulecoeteomyia) japonicus japonicus from northeastern Switzerland showed high susceptibility to West Nile viruses (NY99 and FIN) after oral exposure and incubation under a fluctuating realistic midsummer temperature regime. Infectious virus particles of the WNV NY99 strain were isolated from saliva of Ae. japonicus. The autochthonous species of Culex pipiens was susceptible to WNV NY99 but not to the WNV FIN strain.