J亚群禽白血病病毒gp85结合细胞受体及影响病毒复制分子机制研究

J 亚群禽白血病病毒（ALV-J）囊膜表面蛋白gp85通过其受体结合域（RBD）与细胞受体（chNHE1）结合是启动感染的关键步骤，囊膜蛋白与受体的结合力直接影响病毒的进入和复制能力。我们前期研究发现，近年广泛流行、严重危害我国养禽业的ALV-J国内流行株的复制能力显著高于原型株，其gp85基因明显变异。因此我们推测gp85基因变异可能与病毒复制能力增强直接相关，但gp85基因如何调控、影响病毒复制，机制尚不明确。本项目以ALV-J gp85与受体互作特性为研究对象，鉴定gp85的RBD，比较ALV-J原型株与国内流行株gp85与受体结合力差异，鉴定影响结合力差异的关键氨基酸，揭示gp85蛋白与受体结合的分子细节。构建关键氨基酸突变的嵌合病毒，通过进入能力和体内外复制能力综合评价，阐明gp85基因变异影响病毒复制能力的分子机制，为进一步阐明ALV-J入侵机制和研制有效防控技术奠定重要基础。

Gp85 of avian leukosis virus subgroup J binds cell receptors (chNHE1) by its receptor binding domain (RBD) to initiate ALV infection. Studies have shown that the binding affinity of envelope protein and receptor directly influences the replication ability of virus. Our previous research found that the replication ability of ALV-J domestic strains isolated in recent years in China is significantly higher than that of the prototype strain, and the gp85 genes have obvious variation. Therefore, our scientific hypothesis is that gp85 amino acid variation may be related to the enhancement of viral replication. To test this hypothesis, we design this project. We will identify the RBD of ALV-J gp85 and compare the receptor binding affinity of gp85 of ALV-J domestic strain with the prototype strains. Further, the important amino acids of gp85, which leads to receptor binding affinity differences, will be screened and identified. Finally, the chimeric viruses, with key amino acid mutations that affect the receptor binding affinity, will be constructed and rescued. The abilities of entry into cell and the replication in vivo and in vivo of chimeric viruses will be evaluated. These results are contributed to elucidate the molecular mechanism of enhancing ALV-J domestic strains replication capacity. The results of this research will provide an important theoretical basis for exploring the mechanism of ALV-J invasion and also provide a new insight for the development of effective prevention and control technology.