新城疫病毒（Newcastle disease virus，NDV）通过被膜上血凝素-神经氨酸酶蛋白（Hemagglutinin-neuraminidase，HN）与细胞表面唾液酸受体结合完成病毒感染的吸附过程。课题组前期研究中，发现硫酸化川明参多糖具有抗NDV活性，初步作用机理研究表明其能竞争性地与HN蛋白结合从而阻断病毒在早期吸附阶段感染细胞，但具体作用位点不清楚。因此，本课题拟通过晶体学技术研究NDV HN蛋白与硫酸化多糖相互作用的空间构象，得到具体作用位点，并分析HN蛋白结合硫酸化多糖后构象的变化；采用定点突变技术构建相关氨基酸突变的蛋白表达载体，测定硫酸化多糖抑制NDV吸附能力的变化，以确证其作用位点。本课题的研究结果可为抑制NDV感染靶标药物的设计奠定基础。

The attachment of Newcastle disease virus (NDV) to host cells is achieved by the hemagglutinin-neuraminidase (HN) protein binding to the sialic acid receptors on the cell surface. In the previous study, we found that sulfated Chuanmingshen violaceum polysaccharides (sCVPS) were potent inhibitors of NDV infection and the preliminary mechanism of action was attributed to the interference with virus adsorption by competitively binding to HN protein. However, the action sites are still unknown. This study is conducted to determine the interaction of sCVPS with HN protein and obtain the action sites through X-ray crystallography. After binding to sulfated polysaccharides, the conformational changes of HN protein will also be solved. Then, the site-directed mutagenesis will be employed to construct the mutations of amino acid residues related to interaction with sCVPS, and the mutational HN protein will be expressed in cells and the changes of adsorption ability will be evaluated in order to confirm the actions sites. This study would lay the foundation for the design of new anti-NDV drugs based on these action sites.