Morrison M E, He Y J, Wien M W, Hogle J M, Racaniello V R
Department of Microbiology, Columbia University College of Physicians & Surgeons, New York, New York 10032.
J Virol. 1994 Apr;68(4):2578-88. doi: 10.1128/JVI.68.4.2578-2588.1994.
Poliovirus initiates infection of primate cells by binding to the poliovirus receptor, Pvr. Mouse cells do not bind poliovirus but express a Pvr homolog, Mph, that does not function as a poliovirus receptor. Previous work has shown that the first immunoglobulin-like domain of the Pvr protein contains the virus binding site. To further identify sequences of Pvr important for its interaction with poliovirus, stable cell lines expressing mutated Pvr molecules were examined for their abilities to bind virus and support virus replication. Substitution of the amino-terminal domain of Mph with that of Pvr yields a molecule that can function as a poliovirus receptor. Cells expressing this chimeric receptor have normal binding affinity for poliovirus, yet the kinetics of virus replication are delayed. Results of virus alteration assays indicate that this chimeric receptor is defective in converting native virus to 135S altered particles. This defect is not observed with cells expressing receptor recombinants that include Pvr domains 1 and 2. Because altered particles are believed to be an intermediate in poliovirus entry, these findings suggest that Pvr domains 2 and 3 participate in early stages of infection. Additional mutants were made by substituting variant Mph residues for the corresponding residues in Pvr. The results were interpreted by using a model of Pvr predicted from the known structures of other immunoglobulin-like V-type domains. Analysis of stable cell lines expressing the mutant proteins revealed that virus binding is influenced by mutations in the predicted C'-C" loop, the C" beta-strand, the C"-D loop, and the D-E loop. Mutations in homologous regions of the immunoglobulin-like CD4 molecule alter its interaction with gp120 of human immunodeficiency virus type 1. Cells expressing Pvr mutations on the predicted C" edge do not develop cytopathic effect during poliovirus infection, suggesting that poliovirus-induced cytopathic effect may be induced by the virus-receptor interaction.
脊髓灰质炎病毒通过与脊髓灰质炎病毒受体Pvr结合来启动对灵长类细胞的感染。小鼠细胞不与脊髓灰质炎病毒结合，但表达一种Pvr同源物Mph，它不能作为脊髓灰质炎病毒受体发挥作用。先前的研究表明，Pvr蛋白的第一个免疫球蛋白样结构域包含病毒结合位点。为了进一步确定Pvr中对其与脊髓灰质炎病毒相互作用重要的序列，对表达突变Pvr分子的稳定细胞系进行了检测，以评估它们结合病毒和支持病毒复制的能力。用Pvr的氨基末端结构域替换Mph的氨基末端结构域，产生了一种可以作为脊髓灰质炎病毒受体发挥作用的分子。表达这种嵌合受体的细胞对脊髓灰质炎病毒具有正常的结合亲和力，但病毒复制的动力学延迟。病毒改变试验的结果表明，这种嵌合受体在将天然病毒转化为135S改变颗粒方面存在缺陷。在表达包含Pvr结构域1和2的受体重组体的细胞中未观察到这种缺陷。由于改变颗粒被认为是脊髓灰质炎病毒进入过程中的一个中间体，这些发现表明Pvr结构域2和3参与感染的早期阶段。通过用Mph变体残基替换Pvr中的相应残基制备了其他突变体。结果通过使用根据其他免疫球蛋白样V型结构域的已知结构预测的Pvr模型进行解释。对表达突变蛋白的稳定细胞系的分析表明，病毒结合受到预测的C'-C"环、C"β链、C"-D环和D-E环中的突变的影响。免疫球蛋白样CD4分子同源区域的突变会改变其与1型人类免疫缺陷病毒的gp120的相互作用。在预测的C"边缘表达Pvr突变的细胞在脊髓灰质炎病毒感染期间不会产生细胞病变效应，这表明脊髓灰质炎病毒诱导的细胞病变效应可能是由病毒-受体相互作用诱导的。
