The article by Stephen C. Harrison discusses the mechanism of viral membrane fusion, which is crucial for the entry of viruses into host cells. Viral fusion proteins facilitate this process by undergoing large-scale conformational changes triggered by ligands, such as pH changes or receptor binding. These proteins vary in structure but share a common mechanism: they form a bridge between the viral and host cell membranes, leading to the fusion of the two bilayers. The article provides detailed descriptions of three viral fusion proteins—hemagglutinin from influenza virus, E protein from flaviviruses, and G protein from vesicular stomatitis virus)—to illustrate how different structures have evolved to implement this mechanism. Fusion inhibitors, which can block the fusion process, are also discussed as potential antiviral agents. The article highlights the importance of understanding the structural and functional details of viral fusion proteins for developing effective antiviral strategies.The article by Stephen C. Harrison discusses the mechanism of viral membrane fusion, which is crucial for the entry of viruses into host cells. Viral fusion proteins facilitate this process by undergoing large-scale conformational changes triggered by ligands, such as pH changes or receptor binding. These proteins vary in structure but share a common mechanism: they form a bridge between the viral and host cell membranes, leading to the fusion of the two bilayers. The article provides detailed descriptions of three viral fusion proteins—hemagglutinin from influenza virus, E protein from flaviviruses, and G protein from vesicular stomatitis virus)—to illustrate how different structures have evolved to implement this mechanism. Fusion inhibitors, which can block the fusion process, are also discussed as potential antiviral agents. The article highlights the importance of understanding the structural and functional details of viral fusion proteins for developing effective antiviral strategies.