Semliki forest virusTogaviridae InfectionsViral Envelope ProteinsSpike Glycoprotein, CoronavirusAlphavirus InfectionsArbovirus InfectionsAlphavirusCricetinaeSindbis VirusMembrane FusionCell LineVirus ReplicationViral ProteinsViral InterferenceViral Fusion ProteinsRNA, ViralSARS VirusTreesReceptors, VirusDefective Viruses