Department of Microbiology, National Center of Infectious and Parasitic Diseases, Sofia, Bulgaria.
Department of Microbiology, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece.
J Clin Virol. 2020 Jun;127:104365. doi: 10.1016/j.jcv.2020.104365. Epub 2020 Apr 11.
West Nile virus (WNV) lineage 2, and especially the Hungarian clade, predominates in Europe. Most of the Hungarian clade strains cluster into 2 groups: Central/South-West European and Balkan.
Since there was not any study on WNV in mosquitoes in Bulgaria, the present study was designed to test Culex spp. mosquitoes in areas near the Danube river. The aim of the study was to gain an insight into the recent molecular epidemiology of WNV in Bulgaria.
A total of 1871 Culex pipiens mosquitoes collected in 2018 and clinical samples from 23 patients with West Nile neuroinavsive disease observed in 2018 and 2019 were tested by TaqMan RT-PCR and RT-nested PCR and PCR products were sequenced.
WNV RNA was detected in clinical samples from 10 patients and in five (12.2 %) of 41 pools of Cx. pipiens mosquitos by realtime RT-PCR, resulting in a minimum infection rate of mosquitoes of 0.27 %. Phylogenetic analysis based on partial NS3 gene sequences from one clinical sample and four mosquito pools showed that all sequences clustered into the Hungarian clade of WNV lineage 2 and all but one were identical to respective sequences from Romania. Whole genome sequences of one mosquito pool belong to the Hungarian group of WNV lineage 2 and cluster in a separate subclade from the Bulgarian strain from 2015, suggesting that at least two different introductions occurred in Bulgaria.
The current study provides insights into the geographic distribution of WNV in Bulgaria.
西尼罗河病毒（WNV）谱系 2，尤其是匈牙利分支，在欧洲占主导地位。大多数匈牙利分支菌株分为 2 组：中欧/西南欧和巴尔干。
由于在保加利亚没有关于蚊子中的 WNV 的研究，本研究旨在检测多瑙河附近地区的库蚊属蚊子。该研究的目的是深入了解保加利亚最近的 WNV 分子流行病学。
总共检测了 2018 年采集的 1871 只库蚊和 2018 年和 2019 年观察到的 23 例西尼罗河神经侵袭性疾病患者的临床样本，采用 TaqMan RT-PCR 和 RT-巢式 PCR 进行检测，并对 PCR 产物进行测序。
通过实时 RT-PCR 在 10 例临床样本和 5 例（12.2%）41 只库蚊的蚊群中检测到 WNV RNA，导致蚊子的最低感染率为 0.27%。基于来自 1 例临床样本和 4 个蚊群的 NS3 基因部分序列的系统发育分析表明，所有序列均聚类到 WNV 谱系 2 的匈牙利分支，除 1 个序列外，所有序列均与罗马尼亚的相应序列相同。一个蚊群的全基因组序列属于 WNV 谱系 2 的匈牙利组，与 2015 年保加利亚株系聚类在一个单独的亚分支中，表明至少在保加利亚发生了两次不同的传入。
本研究提供了保加利亚 WNV 地理分布的见解。
