Kolb A F, Hegyi A, Siddell S G
Institute of Virology and Immunology, University of Würzburg, Germany.
J Gen Virol. 1997 Nov;78 ( Pt 11):2795-802. doi: 10.1099/0022-1317-78-11-2795.
Aminopeptidase N (APN) is the major cell surface receptor for group 1 coronaviruses. In this study, we have isolated and characterized a feline APN cDNA and shown that the transfection of human embryonic kidney cells with this cDNA renders them susceptible to infection with the feline coronavirus feline infectious peritonitis virus, the human coronavirus (HCV) 229E and the porcine coronavirus porcine transmissible gastroenteritis virus. By using chimeric APN genes, assembled from porcine and feline sequences, we have shown that, analogously to the human APN protein, a region within the amino-terminal part of the feline APN protein (encompassing amino acids 132-295) is essential for its HCV 229E receptor function. Furthermore, by comparing the relevant feline, human and porcine APN sequences, we were able to identify a hypervariable stretch of eight amino acids that are more closely related in the feline and human APN proteins than in the porcine APN molecule. Using PCR-directed mutagenesis, we converted this stretch of amino acids within the porcine APN molecule to the corresponding residues of the human APN molecule. These changes were sufficient to convert porcine APN into a functional receptor for HCV 229E and thus define a small number of residues that are critically important for the HCV 229E receptor function of human APN.
氨肽酶N（APN）是1型冠状病毒的主要细胞表面受体。在本研究中，我们分离并鉴定了猫APN cDNA，并表明用该cDNA转染人胚肾细胞可使其易受猫冠状病毒猫传染性腹膜炎病毒、人冠状病毒（HCV）229E和猪冠状病毒猪传染性胃肠炎病毒的感染。通过使用由猪和猫序列组装而成的嵌合APN基因，我们已经表明，类似于人APN蛋白，猫APN蛋白氨基末端部分内的一个区域（包含氨基酸132 - 295）对其HCV 229E受体功能至关重要。此外，通过比较相关的猫、人和猪APN序列，我们能够鉴定出一段由八个氨基酸组成的高变区，该区域在猫和人APN蛋白中比在猪APN分子中更为密切相关。利用PCR定向诱变，我们将猪APN分子内的这段氨基酸序列转换为人APN分子的相应残基。这些变化足以将猪APN转化为HCV 229E的功能性受体，从而确定了对人APN的HCV 229E受体功能至关重要的少数几个残基。
