Biologic, antigenic and full-length genomic characterization of a bovine-like coronavirus isolated from a giraffe
Biologic, antigenic and full-length genomic characterization of a bovine-like coronavirus isolated from a giraffe
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DOI：
10.1128/jvi.02361-06
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发表时间：
2007-05-01
影响因子：
5.4
通讯作者：
Saif, Linda J.
中科院分区：
文献类型：
--
作者：
Hasoksuz, Mustafa;Alekseev, Konstantin;Saif, Linda J.
冠状病毒（cov）具有较大的RNA基因组，并以准物种的形式存在，这增加了适应性突变和种间传播的可能性。近年来，冠状病毒被认为是圈养野生反刍动物的重要病原体。这是在美国野生动物园从长颈鹿（Giraffa camelopardalis）身上分离出一种牛状冠状病毒并进行详细遗传、生物学和抗原性鉴定的第一份报告。应用免疫电镜技术在3只轻至重度腹泻长颈鹿粪便样本中检测到冠状病毒颗粒。从其中一个长颈鹿样本中分离出一株冠状病毒（GiCoV-OH3），并成功适应于人直肠肿瘤18细胞培养的连续传代。血凝试验、受体破坏酶活性、血凝抑制和荧光焦点中和试验显示，GiCoV-OH3分离物与呼吸道和肠道牛冠状病毒（BCoV）菌株之间存在密切的生物学和抗原性关系。当将GiCoV-OH3口服接种到bcov血清阴性的非生物犊牛时，可在2至3天内引起严重腹泻和病毒脱落。进行序列比较和系统发育分析，以评估其与其他冠状病毒的遗传相关性。分子鉴定证实新分离物属于哺乳动物冠状病毒2a类群，与肠道bcov BCoV-ENT和BCoV-DB2的亲缘关系较近，而BCoV-Mebus的亲缘关系较远。对GiCoV-OH3刺突基因的详细序列分析表明，S1亚基可变区（从氨基酸543到氨基酸547）存在缺失，该区域与其他冠状病毒的致病性和组织亲和性有关。在结构蛋白中发现的点突变（通过比较GiCoV-OH3、BCoV-ENT、BCoV-DB2和BCoV-Mebus）在GiCoV-OH3、BCoV-ENT和BCoV-DB2中最为保守，而在非结构蛋白中发现的大多数点突变是GiCoV-OH3所特有的。我们的研究结果证实了一种类似牛的冠状病毒的存在，这种冠状病毒可以从野生反刍动物（即长颈鹿）传播给牛，但具有与bcov不同的某些遗传特性。
Coronaviruses (CoVs) possess large RNA genomes and exist as quasispecies, which increases the possibility of adaptive mutations and interspecies transmission. Recently, CoVs were recognized as important pathogens in captive wild ruminants. This is the first report of the isolation and detailed genetic, biologic, and antigenic characterization of a bovine-like CoV from a giraffe (Giraffa camelopardalis) in a wild-animal park in the United States. CoV particles were detected by immune electron microscopy in fecal samples from three giraffes with mild-to-severe diarrhea. From one of the three giraffe samples, a CoV (GiCoV-OH3) was isolated and successfully adapted to serial passage in human rectal tumor 18 cell cultures. Hemagglutination assays, receptor-destroying enzyme activity, hemagglutination inhibition, and fluorescence focus neutralization tests revealed close biological and antigenic relationships between the GiCoV-OH3 isolate and selected respiratory and enteric bovine CoV (BCoV) strains. When orally inoculated into a BCoV-seronegative gnotobiotic calf, GiCoV-OH3 caused severe diarrhea and virus shedding within 2 to 3 days. Sequence comparisons and phylogenetic analyses were performed to assess its genetic relatedness to other CoVs. Molecular characterization confirmed that the new isolate belongs to group 2a of the mammalian CoVs and revealed closer genetic relatedness between GiCoV-OH3 and the enteric BCoVs BCoV-ENT and BCoV-DB2, whereas BCoV-Mebus was more distantly related. Detailed sequence analysis of the GiCoV-OH3 spike gene demonstrated the presence of a deletion in the variable region of the S1 subunit (from amino acid 543 to amino acid 547), which is a region associated with pathogenicity and tissue tropism for other CoVs. The point mutations identified in the structural proteins (by comparing GiCoV-OH3, BCoV-ENT, BCoV-DB2, and BCoV-Mebus) were most conserved among GiCoV-OH3, BCoV-ENT, and BCoV-DB2, whereas most of the point mutations in the nonstructural proteins were unique to GiCoV-OH3. Our results confirm the existence of a bovine-like CoV transmissible to cattle from wild ruminants, namely, giraffes, but with certain genetic properties different from those of BCoVs.