Kyoto Biken Laboratories, Inc., 24-16 Makishima, Uji-city, Kyoto 611-0041, Japan.
J Clin Microbiol. 2010 May;48(5):1795-800. doi: 10.1128/JCM.02339-09. Epub 2010 Mar 10.
Torovirus, a member of the Coronaviridae family, is a gastrointestinal infectious agent that has been identified in humans, cattle, pigs, and equines. Toroviruses, except equine torovirus, are difficult to propagate in cell culture; indeed, to date, only the Aichi/2004 strain of bovine torovirus (BToV) has been isolated among the human, bovine, and porcine toroviruses. In the present study, four cytopathogenic BToVs were isolated from diarrheal feces of the cattle using the HRT-18 cell line, and their genetic and antigenic properties were compared. The cytopathogenic features of BToV isolates in HRT-18 cells were similar to those of the Aichi/2004 strain. However, none of the isolates showed cytopathogenic effects in the HRT-18 cells of different origin, suggesting that one significant factor contributing to the cytopathogenicity of BToV depends on properties of the HRT-18 cells themselves. All BToVs isolated were able to agglutinate mouse, but not chicken, erythrocytes, while they lacked receptor-destroying enzyme activity. Analysis of the N terminus of the spike gene showed that three isolates, but not the Gifu-2007TI/E strain, were phylogenetically located in cluster 1 and its analogs and revealed high cross-reactivity with each other, as demonstrated by neutralization (NT) and hemagglutination inhibition (HI) assays. The Gifu-2007TI/E strain was classified close to cluster 2 and exhibited relatively low cross-reactivity with these viruses; however, the difference was not sufficient to classify BToVs into serotypes, suggesting that at least two subtypes distinguishable by the structure of the N terminus of the spike gene and that both NT and HI tests may be exist.
环曲病毒，冠状病毒科的一个成员，是一种已在人类、牛、猪和马中鉴定出的胃肠道传染性病原体。除马环曲病毒外，环曲病毒在细胞培养中难以繁殖；事实上，到目前为止，只有牛环曲病毒（BToV）的 Aichi/2004 株在人类、牛和猪环曲病毒中被分离出来。在本研究中，使用 HRT-18 细胞系从腹泻牛粪便中分离出 4 株致细胞病变的 BToV，并比较了它们的遗传和抗原特性。BToV 分离株在 HRT-18 细胞中的致细胞病变特征与 Aichi/2004 株相似。然而，没有一种分离株在不同来源的 HRT-18 细胞中表现出致细胞病变作用，这表明导致 BToV 致细胞病变的一个重要因素取决于 HRT-18 细胞本身的特性。所有分离的 BToV 均能凝集鼠红细胞，但不能凝集鸡红细胞，同时它们缺乏受体破坏酶活性。对刺突基因 N 端的分析表明，3 个分离株，但不是 Gifu-2007TI/E 株，在系统进化上位于簇 1及其类似物中，并且在中和（NT）和血凝抑制（HI）试验中彼此表现出高度的交叉反应性。Gifu-2007TI/E 株被归类为接近簇 2，与这些病毒的交叉反应性相对较低；然而，差异不足以将 BToV 分为血清型，这表明至少存在两种亚型，可通过刺突基因 N 端的结构来区分，并且可能存在 NT 和 HI 试验。
