Molecular characterization of the re-emerging West Nile virus in avian species and equids in Israel, 2018, and pathologi
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Parasites & Vectors Open Access
RESEARCH
Molecular characterization of the re‑emerging West Nile virus in avian species and equids in Israel, 2018, and pathological description of the disease Gili Schvartz1,4†, Yigal Farnoushi2†, Asaf Berkowitz2, Nir Edery3, Shelly Hahn3, Amir Steinman4, Avishai Lublin2*† and Oran Erster1,5*†
Abstract Background: In this report we describe the molecular and pathological characteristics of West Nile virus (WNV) infection that occurred during the summer and fall of 2018 in avian species and equines. WNV is reported in Israel since the 1950s, with occasional outbreaks leading to significant morbidity and mortality in birds, high infection in horses and humans, and sporadic fatalities in humans. Methods: Animal and avian carcasses in a suitable condition were examined by post-mortem analysis. Tissue samples were examined for WNV by RT-qPCR and the viral load was quantified. Samples with sufficient material quality were further analyzed by Endpoint PCR and sequencing, which was used for phylogenetic analysis. Tissue samples from positive animals were used for culturing the virus in Vero and C6/36 cells. Results: WNV RNA was detected in one yellow-legged gull (Larus michahellis), two long-eared owls (Asio otus), two domesticated geese (Anser anser), one pheasant (Phasianus colchicus), four hooded crows (Corvus cornix), three horses and one donkey. Pathological and histopathological findings were characteristic of viral infection. Molecular analysis and viral load quantification showed varying degrees of infection, ranging between 70–1.4 × 106 target copies per sample. Phylogenetic analysis of a 906-bp genomic segment showed that all samples belonged to Lineage 1 clade 1a, with the following partition: five samples from 2018 and one sample detected in 2016 were of Cluster 2 Eastern European, two of Cluster 2 Mediterranean and four of Cluster 4. Four of the positive samples was successfully propagated in C6/36 and Vero cell lines for further work. Conclusions: WNV is constantly circulating in wild and domesticated birds and animals in Israel, necessitating constant surveillance in birds and equines. At least three WNV strains were circulating in the suspected birds and animals examined. Quantitative analysis showed that the viral load varies significantly between different organs and tissues of the infected animals. Keywords: West-nile virus, Avian species, Equids, Histopathology, Phylogenetic analysis *Correspondence: [email protected]; [email protected] † Gili Schvartz and Yigal Farnoushi contributed equally to this work † Avishai Lublin and Oran Erster are senior authors 2 Division of Avian diseases, Kimron Veterinary Institute, Bet Dagan, Israel 5 Present Address: Central Virology Laboratory, Israel Ministry of Health, Sheba Medical Center, Ramat Gan, Israel Full list of author information is available at the end of the article
Background West Nile virus (WNV) is a ssRNA virus belonging to the family Flaviviridae, genus Flavivirus and is the causative agent of
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