College of Veterinary Medicine, Northwest A&F University, Yangling, 712100, China.
Department of Infectious Diseases, The Second Clinical Medical College of Jinan University, Shenzhen, 518020, China.
Virol Sin. 2022 Oct;37(5):664-675. doi: 10.1016/j.virs.2022.07.002. Epub 2022 Jul 6.
Interferon-inducible transmembrane protein 3 (IFITM3) inhibits influenza virus infection by blocking viral membrane fusion, but the exact mechanism remains elusive. Here, we investigated the function and key region of IFITM3 in blocking influenza virus entry mediated by hemagglutinin (HA). The restriction of IFITM3 on HA-mediated viral entry was confirmed by pseudovirus harboring HA protein from H5 and H7 influenza viruses. Subcellular co-localization and immunocoprecipitation analyses revealed that IFITM3 partially co-located with the full-length HA protein and could directly interact with HA subunit but not HA subunit of H5 and H7 virus. Truncated analyses showed that the transmembrane domain of the IFITM3 and HA subunit might play an important role in their interaction. Finally, this interaction of IFITM3 was also verified with HA subunits from other subtypes of influenza A virus and influenza B virus. Overall, our data demonstrate for the first time a direct interaction between IFITM3 and influenza HA protein via the transmembrane domain, providing a new perspective for further exploring the biological significance of IFITM3 restriction on influenza virus infection or HA-mediated antagonism or escape.
干扰素诱导跨膜蛋白 3（IFITM3）通过阻断病毒膜融合来抑制流感病毒感染，但确切机制仍不清楚。在这里，我们研究了 IFITM3 在阻断血凝素（HA）介导的流感病毒进入中的功能和关键区域。含有 H5 和 H7 流感病毒 HA 蛋白的假病毒证实了 IFITM3 对 HA 介导的病毒进入的限制。亚细胞共定位和免疫沉淀分析表明，IFITM3 部分与全长 HA 蛋白共定位，并可直接与 HA 亚基相互作用，但不能与 H5 和 H7 病毒的 HA 亚基相互作用。截断分析表明，IFITM3 的跨膜域和 HA 亚基可能在它们的相互作用中发挥重要作用。最后，还通过来自其他亚型流感 A 病毒和流感 B 病毒的 HA 亚基验证了这种相互作用。总体而言，我们的数据首次证明了 IFITM3 通过跨膜域与流感 HA 蛋白的直接相互作用，为进一步探索 IFITM3 对流感病毒感染或 HA 介导的拮抗或逃逸的限制的生物学意义提供了新的视角。
