Cryo-EM structures determined by the Modis group show how the innate immune sensor MDA5 recognizes viral RNA by forming filaments. ATP hydrolysis is coupled to structural changes in the filament, which are proposed to promote discrimination between viral and cellular RNAs. Depicted here on day 346 of #LMB365 is a model of an MDA5-dsRNA filament (foreground). A viral dsRNA genome and the endosome that delivered it into the cytosol are shown in the background. Image created by Lesley McKeane (Visual Aids) in consultation with Yorgo Modis.