在意大利的蝙蝠中检测到与中东呼吸综合征相关的两种β-CoV 病毒，并对其全基因组进行了特征分析。
Detection and full genome characterization of two beta CoV viruses related to Middle East respiratory syndrome from bats in Italy.
机构信息
Department of Virology, Istituto Zooprofilattico Sperimentale Lombardia ed Emilia Romagna, Via Antonio Bianchi 9, 25124, Brescia, Italy.
Department of Food Safety, Istituto Superiore di Sanità. Nutrition and Veterinary Public Health, Viale Regina Elena 299, 00161, Rome, Italy.
出版信息
Virol J. 2017 Dec 19;14(1):239. doi: 10.1186/s12985-017-0907-1.
BACKGROUND
Middle East respiratory syndrome coronavirus (MERS-CoV), which belongs to beta group of coronavirus, can infect multiple host species and causes severe diseases in humans. Multiple surveillance and phylogenetic studies suggest a bat origin. In this study, we describe the detection and full genome characterization of two CoVs closely related to MERS-CoV from two Italian bats, Pipistrellus kuhlii and Hypsugo savii.
METHODS
Pool of viscera were tested by a pan-coronavirus RT-PCR. Virus isolation was attempted by inoculation in different cell lines. Full genome sequencing was performed using the Ion Torrent platform and phylogenetic trees were performed using IQtree software. Similarity plots of CoV clade c genomes were generated by using SSE v1.2. The three dimensional macromolecular structure (3DMMS) of the receptor binding domain (RBD) in the S protein was predicted by sequence-homology method using the protein data bank (PDB).
RESULTS
Both samples resulted positive to the pan-coronavirus RT-PCR (IT-batCoVs) and their genome organization showed identical pattern of MERS CoV. Phylogenetic analysis showed a monophyletic group placed in the Beta2c clade formed by MERS-CoV sequences originating from humans and camels and bat-related sequences from Africa, Italy and China. The comparison of the secondary and 3DMMS of the RBD of IT-batCoVs with MERS, HKU4 and HKU5 bat sequences showed two aa deletions located in a region corresponding to the external subdomain of MERS-RBD in IT-batCoV and HKU5 RBDs.
CONCLUSIONS
This study reported two beta CoVs closely related to MERS that were obtained from two bats belonging to two commonly recorded species in Italy (P. kuhlii and H. savii). The analysis of the RBD showed similar structure in IT-batCoVs and HKU5 respect to HKU4 sequences. Since the RBD domain of HKU4 but not HKU5 can bind to the human DPP4 receptor for MERS-CoV, it is possible to suggest also for IT-batCoVs the absence of DPP4-binding potential. More surveillance studies are needed to better investigate the potential intermediate hosts that may play a role in the interspecies transmission of known and currently unknown coronaviruses with particular attention to the S protein and the receptor specificity and binding affinity.
背景
中东呼吸综合征冠状病毒（MERS-CoV）属于冠状病毒β属，可以感染多种宿主物种，并导致人类严重疾病。多项监测和系统发育研究表明其蝙蝠起源。本研究描述了从意大利两种蝙蝠（菊头蝠和大足鼠耳蝠）中分离到的两株与 MERS-CoV 密切相关的冠状病毒的检测和全基因组特征。
方法
通过 pan-coronavirus RT-PCR 检测内脏混合样本。通过接种不同细胞系进行病毒分离。使用 Ion Torrent 平台进行全基因组测序，并使用 IQtree 软件构建系统发育树。使用 SSE v1.2 生成 CoV 聚类 c 基因组的相似性图谱。通过序列同源性方法，使用蛋白质数据库（PDB）预测 S 蛋白受体结合域（RBD）的三维大分子结构（3DMMS）。
结果
两个样本的 pan-coronavirus RT-PCR 结果均为阳性（IT-batCoVs），其基因组结构与 MERS-CoV 相同。系统发育分析显示，一个单系群位于由人类和骆驼起源的 MERS-CoV 序列以及来自非洲、意大利和中国的蝙蝠相关序列组成的β2c 聚类中。与 MERS、HKU4 和 HKU5 蝙蝠序列相比，IT-batCoVs 的 RBD 二级结构和 3DMMS 显示，IT-batCoV 和 HKU5 RBD 中存在两个位于 MERS-RBD 外亚结构域对应区域的 aa 缺失。
结论
本研究报道了从意大利两种常见蝙蝠（菊头蝠和大足鼠耳蝠）中分离到的两株与 MERS 密切相关的β冠状病毒。RBD 分析显示 IT-batCoVs 和 HKU5 与 HKU4 序列具有相似的结构。由于 HKU4 的 RBD 结构域而非 HKU5 可以与人类 DPP4 受体结合，因此也可以推测 IT-batCoVs 缺乏与 DPP4 结合的潜力。需要进行更多的监测研究，以更好地调查可能在已知和目前未知冠状病毒的种间传播中发挥作用的中间宿主，特别注意 S 蛋白和受体特异性以及结合亲和力。
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