Erdogan Bamac Ozge, Cizmecigil Utku Y, Mete Asli, Yilmaz Aysun, Aydin Ozge, Tali Hasan E, Tali Besim H, Yilmaz Semaha G, Gurel Aydin, Turan Nuri, Ozsoy Serhat, Vatansever Celik Ezgi, Sadeyen Jean-Remy, Roman-Sosa Gleyder, Iqbal Munir, Richt Juergen A, Yilmaz Huseyin
Department of Pathology, and Veterinary Faculty, Istanbul University-Cerrahpasa, Avcilar, Istanbul, Turkey.
Department of Virology, Veterinary Faculty, Istanbul University-Cerrahpasa, Avcilar, Istanbul, Turkey.
Vector Borne Zoonotic Dis. 2021 Nov;21(11):892-899. doi: 10.1089/vbz.2021.0010. Epub 2021 Nov 8.
West Nile fever is a vector-borne viral disease affecting animals and humans causing significant health and economic problems globally. This study was aimed at investigating circulating West Nile virus (WNV) strains in free-ranging corvids in Istanbul, Turkey. Brain, liver, and kidney were collected from corvids ( = 34) between June 2019 and April 2020 and analyzed for the presence of WNV-specific RNA by quantitative RT-PCR. In addition, histopathologic and immunohistochemical examinations were also performed. Samples found to be positive by qRT-PCR were partially sequenced. WNV-specific RNA was detected in 8 of 34 corvids analyzed, which included 7 hooded crows () and 1 Eurasian magpie (). Phylogenetic analysis based on partial WNV sequences from the 8 WNV-positive corvids identified in this study revealed that all sequences clustered within the WNV lineage-2; they were at least 97% homologues to WNV lineage-2 sequences from Slovakia, Italy, Czechia, Hungary, Senegal, Austria, Serbia, Greece, Bulgaria, and Germany. WNV sequences showed a divergence (87.94-94.46%) from sequences reported from Romania, Central African Republic, South Africa, Madagascar, Israel, and Cyprus, which clustered into a different clade of WNV lineage-2. Common histopathologic findings of WNV-positive corvids included lymphoplasmacytic hepatitis, myocarditis, and splenitis. The liver and heart were found to be the tissues most consistently positive for WNV-specific antigen by immunohistochemistry, followed by the kidney and brain. This study demonstrates for the first time the existence of WNV virus belonging to the genetic lineage-2 in resident corvids in Istanbul, Turkey. We hypothesize that the WNV strains circulating in Istanbul are possibly the result of a spillover event from Europe. Since WNV is a zoonotic pathogen transmitted by mosquito vectors, the emergence of WNV in Istanbul also poses a risk to humans and other susceptible animals in this densely populated city and needs to be addressed by animal and public health authorities.
西尼罗河热是一种由媒介传播的病毒性疾病，影响动物和人类，在全球范围内造成重大的健康和经济问题。本研究旨在调查土耳其伊斯坦布尔自由放养的鸦科鸟类中循环的西尼罗河病毒（WNV）毒株。在2019年6月至2020年4月期间，从鸦科鸟类（n = 34）采集脑、肝和肾，并通过定量逆转录聚合酶链反应分析WNV特异性RNA的存在情况。此外，还进行了组织病理学和免疫组织化学检查。对通过qRT-PCR检测为阳性的样本进行了部分测序。在分析的34只鸦科鸟类中有8只检测到WNV特异性RNA，其中包括7只 hooded crows（冠小嘴乌鸦）和1只欧亚喜鹊。基于本研究中鉴定出的8只WNV阳性鸦科鸟类的部分WNV序列进行的系统发育分析表明，所有序列都聚集在WNV 2型谱系内；它们与来自斯洛伐克、意大利、捷克、匈牙利、塞内加尔、奥地利、塞尔维亚、希腊、保加利亚和德国的WNV 2型谱系序列至少有97%的同源性。WNV序列与来自罗马尼亚、中非共和国、南非、马达加斯加、以色列和塞浦路斯的序列有差异（87.94 - 94.46%），这些序列聚集在WNV 2型谱系的一个不同分支中。WNV阳性鸦科鸟类常见的组织病理学发现包括淋巴细胞性肝炎、心肌炎和脾炎。通过免疫组织化学发现，肝和心脏是WNV特异性抗原最一致呈阳性的组织，其次是肾和脑。本研究首次证明在土耳其伊斯坦布尔的常驻鸦科鸟类中存在属于遗传2型谱系的WNV病毒。我们推测在伊斯坦布尔循环的WNV毒株可能是欧洲溢出事件的结果。由于WNV是一种由蚊媒传播的人畜共患病原体，WNV在伊斯坦布尔的出现也对这个人口密集城市中的人类和其他易感动物构成风险，需要动物和公共卫生当局加以应对。
