Glycoprotein organization of Chikungunya virus particles revealed by X-ray crystallography.

The E1 and E2 glycoproteins of alphaviruses form heterodimers and assemble into spikes on the virus surface, which mediate receptor binding and endocytosis. When the virion encounters acidic pH in the endosome E1 and E2 dissociate and E1 triggers fusion with the endosomal membrane. Two papers now provide the first crystal structures for glycoprotein complexes incorporating E2 at acidic and neutral pH, respectively. Together they provide insight into how fusion activation is controlled in alphaviruses.