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VirusassemblyPaulZhouInstitutPasteurofShanghaiGeneralconsideration•Envelopedviruses–nucleus•Envelopedviruses–cytosol•Non-envelopedviruses–nucleus•Non-envelopedviruses-cytosolStepsinvolveinviralassembly•Viralproteinandnucleotidesynthesis•Viralproteinandnucleotidetrafficking•Encapsidateviralnucleotidestoassembleviralcore•Envelopmentofvirusandretentionofviralglycoproteins(forenvelopedviruses)•Viralrelease:buddingandlysisofcells•Virionmaturation(proteolyticprocess)Intimateinvolvementofcellularmachineryinviralassembly•Cellularpolymeraseoravirus-encodedpolymerasetoviralgenomereplication•Celltranslationalmachineryforviralproteinsynthesis•Cellularsortingmachineryforviralcomponentstraffickingandreleasing•Cellularproteases,membranes,glycosylationmachinery,kinasesandchaperonproteinsforproteinmaturationProteinlocalizationinamammaliancellsBuddingsitesfordifferentvirusesAssemblywithinthecytoplasmbypoliovirus•Replicateexclusivelyinthecytoplasm•Cytoplasmiclocalizationofviralproteinsynthesis,ofviralRNAreplication,andviralparticleassembly.Therefore,itisleasttraffickingwithincells•CellfreetranslationofnakedpoliovirusRNA,synthesisofvirionRNA,andassemblyofinfectiouspoliovirusparticles•ReleasefromapicalsurfaceofpolarizedhumanintestinalepithelialcellsAssemblywithinthenucleusbyAdenovirusandSV40•Viralproteinstraffickingfromthecytoplasmtothenucleus–NLS•Assemblyofemptyproteinshell(252capsomesincluding240hexonsand12pentons)thenencapsidationofviralDNAortheencapsidationofviralDNAoccursalongwithassembly•Aftertheassemblyinthenucleus,viralparticleisreleasedonlysisofthecells.AssemblyofHSV•InHSVaftersynthesisoftheγcapsidproteins,VP5,VP26andVP23areinitiallyassembledinthecytoplasm.TheyarelocalizedintothenucleusbyVP19Corpro-VP22a,wherethefinalcapsidassemblyoccurs.•Duringthefinalcapsidassemblyemptyshellscontaininganinternalscaffoldingareassembledfirst.ThenviralDNAisinsertedintothecapsid.•AfterencapsidationoftheviralDNA,thenucleocapsidsbudthroughtheinnernuclearmembrane,inwhichinteractionsbetweencapsidandtegumentproteinsandbetweentegumentproteinsandviralglycoproteinsoccur.•Twogeneralpathwayshavebeenproposedinegressofvirionparticlesfromthespacebetweentheinnnerandouternuclearmembranestotheexteriorofinfectedcells.AssemblyofHSVAssemblyofNCVAssemblyofinfluenzavirusIssuesininfluenzavirusassembly•Packagingasegmentedgenome:randomversusprecision•Exportofnucleocapsidsfromthenucleustothecytoplasm:theroleofM1andNS2•ThebiogenesisofHAproteins:theroleofcellularendopeptidaseandM2•TheroleofNAandmonoubiquitinationinvirionbuddingfromcellsurfaceAssemblyofHIVImportantissuesinHIVassembly•ExportofviralRNA:theroleofrevprotein•Biosynthesisofenvelopeproteins:theroleofendopeptidases•Egressofvirion:theroleoflatedomainofgagp6andgagMAproteins•DownregulationofCD4:theroleofnef,vpu,andgp120proteins•Theroleofexosomeandlipidraft•Thematurationofvirion:theroleofviralproteaseCompareassemblyamongretrovirusesAssemblyofvacciniavirusSummary•Ourknowledgeinviralassemblyisincompleteandfragmented.Somearestillverydescriptive.•Viralassemblyinvolvesintimateinteractionsbetweenviralandhostfactors•Understandingtheseinteractionswillshedlightonbiologicalprocessesofcells•Understandingtheseinteractionswillhelptodevelopnewtherapeuticinterventionstrategies