Thecorona-likespikesorpeplomersonthesurfaceofthevirionunderelectronicmicroscopearethemoststrikingfeaturesofcoronaviruses.TheS(spike)proteinisthelargeststructuralprotein,with1,255aminoacids,intheviralgenome.Itsstructurecanbepidedintothreeregions:alongN-terminalregionintheexte-rior,acharacteristictransmembrane(TM)region,andashortC-terminusintheinteriorofavirion.WedetectedfifteensubstitutionsofnucleotidesbycomparisonswiththeseventeenpublishedSARS-CoVgenomesequences,eight(53.3%)ofwhicharenon-synonymousmutationsleadingtoaminoacidalternationswithpredictedphysiochemicalchanges.ThepossibleantigenicdeterminantsoftheSproteinarepredicted,andtheresultisconfirmedbyELISA(enzyme-linkedimmunosorbentassay)withsynthesizedpeptides.AnotherprofoundfindingisthatthreedisulfidebondsaredefinedattheC-terminuswiththeN-terminusoftheE(envelope)pro-tein,basedonthetypicalsequenceandpositions,thusestablishingthestructuralconnectionwiththesetwoimportantstructuralproteins,ifconfirmed.Phyloge-neticanalysisrevealsseveralconservedregionsthatmightbepotentdrugtargets.
