Two amino acid changes at the N-terminus of transmissible gastroenteritis coronavirus spike protein result in the loss of enteric tropism
Two amino acid changes at the N-terminus of transmissible gastroenteritis coronavirus spike protein result in the loss of enteric tropism
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DOI：
10.1006/viro.1996.8344
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发表时间：
1997-01-20
期刊：
影响因子：
3.7
通讯作者：
Enjuanes, L
中科院分区：
文献类型：
--
作者：
Ballesteros, ML;Sanchez, CM;Enjuanes, L
为了研究 TGEV 趋向性的分子基础，产生了感染肠道和呼吸道的传染性胃肠炎冠状病毒（TGEV）的 PUR46-MAD 株与仅感染呼吸道的 PTV 株之间的重组体集合。重组分离频率约为每个核苷酸10(-9)个重组体，并且S基因5'端的重组分离频率比基因组其他区域高3.7倍。对三十个重组体进行噬菌斑纯化并进行表型和遗传学表征。所有重组病毒都有一次交叉，并分别从肠道和呼吸道亲本遗传了其基因组的 5' 和 3' 半部分。根据交叉位置，重组病毒分为三组，分别命名为 1 至 3。第 1 组重组体在 S 基因中存在交换，而在第 2 组和第 3 组中，交换分别位于 ORF1b 和 ORF1a 中。研究了重组体的向性。第1组重组体具有肠道和呼吸道趋向性，而第2组重组体感染呼吸道，但不感染肠道。两组病毒的差异在于位置 214 和 655 处的两个核苷酸变化。这两种变化原则上可能是造成肠向性丧失的原因，但只有 655 号核苷酸的变化在呼吸道分离株中特异发现，并且很可能是这个单核苷酸变化导致了 S 蛋白 219 号氨基酸的取代，导致了密切相关的 PUR-46 分离株中肠向性的丧失。现有数据表明，为了用 TGEV 感染肠道细胞，涉及 S 蛋白的两个不同结构域，分别位于氨基酸 522 和 744 之间以及氨基酸 219 周围。第一个结构域与猪氨肽酶 N（TGEV 的细胞受体）结合。在另一个结构域图谱中，有一个性质未明确的第二个因子，但它可能是 TGEV 肠向性所必需的辅助受体的结合位点。 (C) 1997 学术出版社
To study the molecular basis of TGEV tropism, a collection of recombinants between the PUR46-MAD strain of transmissible gastroenteritis coronavirus (TGEV) infecting the enteric and respiratory tracts and the PTV strain, which only infects the respiratory tract, was generated. The recombinant isolation frequency was about 10(-9) recombinants per nucleotide and was 3.7-fold higher at the 5'-end of the S gene than in other areas of the genome. Thirty recombinants were plaque purified and characterized phenotypically and genetically. All recombinant viruses had a single crossover and had inherited the 5'- and 3'-halves of their genome from the enteric and respiratory parents, respectively. Recombinant viruses were classified into three groups, named 1 to 3, according to the location of the crossover. Group 1 recombinants had the crossover in the S gene, while in Groups 2 and 3 the crossovers were located in ORF1b and ORF1a, respectively. The tropism of the recombinants was studied. Recombinants of Group 1 had enteric and respiratory tropism, while Group 2 recombinants infected the respiratory, but not the enteric, tract. Viruses of both groups differed by two nucleotide changes at positions 214 and 655. Both changes may be in principle responsible for the loss of enteric tropism but only the change in nucleotide 655 was specifically found in the respiratory isolates and most likely this single nucleotide change, which leads to a substitution in amino acid 219 of the S protein, was responsible for the loss of enteric tropism in the closely related PUR-46 isolates. The available data indicate that in order to infect enteric tract cells with TGEV, two different domains of the S protein, mapping between amino acids 522 and 744 and around amino acid 219, respectively, are involved. The first domain binds to porcine aminopeptidase N, the cellular receptor for TGEV. In the other domain maps a second factor of undefined nature but which may be the binding site for a coreceptor essential for the enteric tropism of TGEV. (C) 1997 Academic Press