甲型流感病毒（IAV）的表面蛋白血凝素能够通过结合唾液酸及介导病毒膜融合来促进IAV的入侵和核蛋白体的释放，因而靶向HA的化合物有望研发成为新型的IAV侵入抑制剂。项目组前期研究发现深海真菌来源的苯乙酮生物碱类化合物APA-18具有显著的体内外抗IAV作用，且其可能是通过靶向HA蛋白来抑制IAV的侵染。本项目拟首先利用流式细胞术和共聚焦显微镜等对APA-18抗IAV侵染作用机制进行研究，以阐明其对于病毒内吞和膜融合的抑制机理；利用SPR、分子对接和耐药株筛选等方法探讨APA-18作用的HA蛋白结构位点，以揭示APA-18与HA的相互作用模式；利用CPE抑制，空斑实验和小鼠肺炎模型等对APA-18抗IAV作用的构效关系进行研究，以揭示其抗IAV作用的主要药效团。本项目的成功实施不仅为新型抗IAV海洋药物的研发提供物质基础和理论参考，还将为靶向血凝素蛋白的抗IAV治疗提供借鉴。

Hemagglutinin (HA), the surface protein of influenza A virus (IAV), can promote IAV invasion and the release of ribonucleoprotein (RNP) through binding to the sialic acids and mediating viral membrane fusion, thus the compounds targeting HA protein have the potential to be developed into novel entry inhibitors of IAV. Our preliminary studies indicated that the novel benzene ketone alkaloid compound APA-18, derived from Antarctic deep-sea fungus, had significant anti-IAV effects in vitro and in vivo, and it might inhibit the infection of IAV through targeting virus HA protein. On that basis, the project intends to explore the anti-IAV mechanisms of APA-18 by using flow cytometry and confocal microscopy, in order to clarify the mechanisms of its inhibition on virus endocytosis and membrane fusion; To explore the binding sites of APA-18 on HA protein by using SPR, molecular docking, and resistant strain screening methods, so as to reveal the interaction model between APA-18 and HA protein; To investigate the structure-activity relationships of anti-IAV effects of APA-18 by using CPE inhibition, plaque assay and mouse pneumonia model, in order to reveal the main effect group of APA-18. In summary, the implementation of this project will not only provide the material basis and theoretical reference for the development of novel anti-IAV marine drugs, but also provide a reference for the anti-IAV therapy targeting virus HA protein.