Structure of decay-accelerating factor bound to echovirus 7: a virus-receptor complex.

Echoviruses are enteroviruses that belong to Picornaviridae. Many echoviruses use decay-accelerating factor (DAF) as their cellular receptor. DAF is a glycosylphosphatidyl inositol-anchored complement regulatory protein found on most cell surfaces. It functions to protect cells from complement attack. The cryo-electron microscopy reconstructions of echovirus 7 complexed with DAF show that the DAF-binding regions are located close to the icosahedral twofold axes, in contrast to other enterovirus complexes where the viral canyon is the receptor binding site. This novel receptor binding position suggests that DAF is important for the attachment of viral particles to host cells, but probably not for initiating viral uncoating, as is the case with canyon-binding receptors. Thus, a different cell entry mechanism must be used for enteroviruses that bind DAF.