Genetic Characterization of a Neurovirulent West Nile Virus Variant Associated with a Fatal Great Grey Owl Infection.

Katarína Peňazziová,Patrik Pastorek,Martina Ličková,Boris Klempa,Ľuboš Korytár,Kristína Boršová,Tomáš Csank,Diana Rusňáková,Juraj Pistl,Viktória Čabanová,Tomáš Szemes

doi:10.3390/v13040699

Abstract

This study reports on a fatal case of a captive great grey owl infected with the West Nile virus (WNV) in the zoological garden Košice, eastern Slovakia (Central Europe). The tissue samples of the dead owl were used for virus isolation and genetic characterization. The novel isolate is genetically closer to Hungarian, Greek, and Bulgarian strains from the central/southern European clade of lineage 2 than to the strains previously isolated in Slovakia. Interestingly, it carries NS3-249P, a molecular virulence determinant associated with higher neurovirulence, which has not previously been observed in Slovakia. Subsequent serological investigation of the captive owls revealed additional seropositive animals, indicating local WNV transmission. Although no WNV-positive mosquitoes were found, the presence of the WNV principal vector Culex pipiens complex together with the described fatal case and further serological findings indicate an endemic focus of bird-neurovirulent WNV variant in the area.

Highlights

West Nile virus (WNV) and Usutu virus (USUV), both from genus Flavivirus (Flaviviridae), are included in the antigenic complex of the Japanese encephalitis virus (JEV).The natural transmission cycle of all members of the JEV antigen complex includes birds as the main amplification hosts and several mosquito species as vectors
A 17-years old great grey owl died on 29 August 2018
The isolation of WNV from the brain of a dead great grey owl in Zoo Košice uncovered the presence of a novel WNV lineage 2 variants in Slovakia

Summary

Introduction

West Nile virus (WNV) and Usutu virus (USUV), both from genus Flavivirus (Flaviviridae), are included in the antigenic complex of the Japanese encephalitis virus (JEV). The natural transmission cycle of all members of the JEV antigen complex includes birds as the main amplification hosts and several mosquito species as vectors. The mosquito becomes infected during blood-sucking on a viremic bird and remains persistently infected throughout its life, potentially transmitting the virus to all vertebrates on which it feeds. Horses and humans are considered dead-end hosts [1]. Nile district in Uganda in 1937 [2]. Thereafter, WNV became one of the most widespread arboviruses distributed in Africa, Asia, Europe, and Australia.

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