The Acetyl-Esterase Activity of the Hemagglutinin-Esterase Protein of Human Coronavirus OC43 Strongly Enhances the Production of Infectious Virus
The Acetyl-Esterase Activity of the Hemagglutinin-Esterase Protein of Human Coronavirus OC43 Strongly Enhances the Production of Infectious Virus
复制标题
DOI：
10.1128/jvi.02699-12
复制
发表时间：
2013-03-01
影响因子：
5.4
通讯作者：
Talbot, Pierre J.
中科院分区：
文献类型：
--
作者：
Desforges, Marc;Desjardins, Jessica;Talbot, Pierre J.
大多数β冠状病毒具有血凝素酯酶（HE）蛋白，其似乎在结合靶细胞或从靶细胞释放中起作用。由于这种HE蛋白具有从O-乙酰化唾液酸中去除乙酰基的乙酰酯酶活性，因此假定其具有受体破坏酶的作用。然而，HE的确切功能及其酶活性仍然知之甚少。利用中和抗体和重组人冠状病毒OC 43（HCoV-OC 43）的分子克隆，我们的研究结果表明，该HCoV的HE蛋白可能与靶细胞的感染有关，最值得注意的是，在感染性病毒颗粒的产生中是重要的。事实上，在用HCoV-OC 43的各种cDNA感染性克隆（缺乏HE蛋白或携带具有非功能性乙酰酯酶活性的HE蛋白）转染BHK-21细胞后，与参考感染性HCoV-OC 43克隆pBAC-OC 43（FL）相比，我们可重复地不能检测重组感染性病毒。使用表达野生型HE的BHK-21细胞（瞬时或稳定异位表达）进行的互补实验表明，该蛋白质在感染性重组冠状病毒颗粒的产生中起着非常重要的作用，该颗粒随后可以更有效地感染易感上皮细胞和神经元细胞。尽管S蛋白是影响易感细胞的冠状病毒感染的主要病毒因子，但我们的研究结果表明，功能活性HE蛋白增强了HCoV-OC 43的感染特性，并有助于细胞培养物中的有效病毒传播。
Most betacoronaviruses possess an hemagglutinin-esterase (HE) protein, which appears to play a role in binding to or release from the target cell. Since this HE protein possesses an acetyl-esterase activity that removes acetyl groups from O-acetylated sialic acid, a role as a receptor-destroying enzyme has been postulated. However, the precise function of HE and of its enzymatic activity remains poorly understood. Making use of neutralizing antibody and of molecular clones of recombinant human coronavirus OC43 (HCoV-OC43), our results suggest that the HE protein of this HCoV could be associated with infection of target cells and, most notably, is important in the production of infectious viral particles. Indeed, after transfecting BHK-21 cells with various cDNA infectious clones of HCoV-OC43, either lacking the HE protein or bearing an HE protein with a nonfunctional acetyl-esterase enzymatic activity, we were reproducibly unable to detect recombinant infectious viruses compared to the reference infectious HCoV-OC43 clone pBAC-OC43(FL). Complementation experiments, using BHK-21 cells expressing wild-type HE, either transiently or in a stable ectopic expression, demonstrate that this protein plays a very significant role in the production of infectious recombinant coronaviral particles that can subsequently more efficiently infect susceptible epithelial and neuronal cells. Even though the S protein is the main viral factor influencing coronavirus infection of susceptible cells, our results taken together indicate that a functionally active HE protein enhances the infectious properties of HCoV-OC43 and contributes to efficient virus dissemination in cell culture.