特徴

• Background：S1 attaches the virion to the cell membrane by interacting with sialic acid-containing cell receptors, initiating the infection. S2 is a class I viral fusion protein. Under the current model, the protein has at least 3 conformational states： pre-fusion native state, pre-hairpin intermediate state, and post-fusion hairpin state. During viral and target cell membrane fusion, the coiled coil regions （heptad repeats） assume a trimer-of-hairpins structure, positioning the fusion peptide in close proximity to the C-terminal region of the ectodomain. The formation of this structure appears to drive apposition and subsequent fusion of viral and target cell membranes.