Zelus B D, Wessner D R, Dveksler G S, Holmes K V
Department of Microbiology, University of Colorado, Denver 80262, USA.
Adv Exp Med Biol. 1998;440:3-9. doi: 10.1007/978-1-4615-5331-1_1.
The interaction of viruses with specific receptors is an important determinant of viral tissue tropism and species specificity. Our goals are to understand how mouse hepatitis virus (MHV) recognizes its cellular receptor, MHVR, and how post-binding interactions with this receptor influence viral fusion and entry. Murine cells express a variety of cell surface molecule in the biliary glycoprotein (Bgp) family that are closely related to the MHVR. When these proteins are expressed at high levels in cell culture, they function as MHV receptors. We used a baculovirus expression system to produce soluble recombinant murine Bgp receptors in which the transmembrane and cytoplasmic domains have been replaced with a six-histidine tag. The soluble glycoproteins were purified to apparent homogeneity and shown to react with antisera to the native receptor. We compared the virus neutralizing activities of various soluble receptor glycoproteins. Soluble MHVR [sMHVR(1-4)] had 10-20 fold more virus neutralizing activity the soluble protein derived from the Bgp1b glycoprotein [sBgp1b(1-4)], from MHV-resistant SJL mice. The sMHVR(1-4) glycoprotein was 60-100 fold more active than a truncated receptor molecule containing only the first two immunoglobulin-like domains, sMHVR(1,2). The observation that sMHVR lacking domains 3 and 4 neutralizes MHV-A59 very poorly suggests that these domains may influence virus binding or subsequent steps associated with neutralization.
病毒与特定受体的相互作用是病毒组织嗜性和物种特异性的重要决定因素。我们的目标是了解小鼠肝炎病毒（MHV）如何识别其细胞受体MHVR，以及与该受体的结合后相互作用如何影响病毒融合和进入。鼠细胞在胆汁糖蛋白（Bgp）家族中表达多种与MHVR密切相关的细胞表面分子。当这些蛋白质在细胞培养中高水平表达时，它们可作为MHV受体发挥作用。我们使用杆状病毒表达系统来产生可溶性重组鼠Bgp受体，其中跨膜和细胞质结构域已被六组氨酸标签取代。可溶性糖蛋白被纯化至表观均一，并显示与针对天然受体的抗血清发生反应。我们比较了各种可溶性受体糖蛋白的病毒中和活性。可溶性MHVR [sMHVR(1-4)]的病毒中和活性比来自MHV抗性SJL小鼠的Bgp1b糖蛋白[sBgp1b(1-4)]衍生的可溶性蛋白高10-20倍。sMHVR(1-4)糖蛋白的活性比仅包含前两个免疫球蛋白样结构域的截短受体分子sMHVR(1,2)高60-100倍。缺乏结构域3和4的sMHVR对MHV-A59的中和作用非常差，这一观察结果表明这些结构域可能影响病毒结合或与中和相关的后续步骤。
