交大微生物课件lecture9-3essentials of virology

: fication,replicationandLecture9-3EssentialsofVirologyCHAPTER9BROCKBIOLOGYOFSchoolofLifeScienceandBiotechnology,ShanghaiJiaoTongUniversityOverviewofp.250sectionDifferencesbetweenprokaryotesandeukaryotes Entranceintothecell:AbsenceorpresenceofcellwallFormanybacteriophagesonlythegenomeandperhapsonetwoproteinspenetrateintothecytosmForanimal es,theentirevirionoratleastthenucleocapsidentersthecytosmbyendocytosisandthenmustbeSiteforreplication:CellularcompartmentationNocompartmentationinCompartmentationineukaryotes(DNAreplicationandtranscriptionoccurinthenucleus,whereastranslationoccursinthecytosm)Differencesbetweenprokaryoteseukaryotesthat mRNAsynthesisandproteintranslationPolycistronicforMonocistronicforUptakeofanenvelopedvirionbyananimal9.11.29.11.2Classificationof腺毒 嗜肝 沙 逆转 ThetaxonomyofDNA ThetaxonomyofRNA 9.11.3Consequences InfectioninAnimalCells动物细胞后的可能 反转录Figure9-9.12.1 9.12.1Therearetypicallyseveninternalproteins:FourstructuralDNAThevirionalsocontainsspecificcellulartRNAmoleculeThevirionalsocontainsspecificcellulartRNAmoleculeasprimerGenome:Twoidenticalplusss5’cappedand3’CapableofactingasmRNAbutnotusedas Fig9.12.2Geneticmapoftwotypical essrcsrc-cancerformationFig9.25EachendofthegenomicRNAcontainsdirectrepeatsAllretro escontainthefollowingregionsandinthesameorder:gag,encodinginternalstructuralproteins;pol,encodingreversetranscriptaseandintegrase;andenv,encodingenvelopeproteins.9.12.3Replicationprocessof9.12.3Replicationprocessofa反转的过VirionIntegrationoftheDNAcopyintothehostgenomeDNAintomRNAandviralRNALTR:longterminalEntranceintoVirionIntegrationoftheDNAcopyintothehostgenomeDNAintomRNAandviralRNA9.12.4ReversetranscriptiontRNAprimergotfromprevioushostcellReversetranscrptaseisaDNApolymeraseandmusthaveaprimer.Theprimerforretro reversetranscriptionisaspecificcellulartRNA.ThetRNAusedasprimerisbroughtintothevironfromtheprevioushostcell.V.SUB-VIRALPARTICLES 9.13ViroidsandPrions Viroidsaresmall,circular,single-strandedRNASize:246to399Considerabledegreeofsequencehomology(mayhavecommonevolutionaryroots)具有高度的同源性（可能有相同的进化）ExtracellularformnakedRNAnoproteincapsidTheRNAcontainsnoprotein-encodinggenes.胞外形式：露的RNA，无蛋白衣壳，RNA中也无编码蛋白质的Fig9.27Structureofviroids.Single-strandedcircularRNAcanformaseeminglydouble-strandedstructurebyintrastrandbase-pairing.Viroidentersthe ntthroughawound.Itisreplicatedinthehostcellnucleusbyoneofthe ntRNApolymerases. ntscanbesymptomlessordevelopthatrangefrommildtolethal,dependingontheExtracellularform:entirelyproteindoesnotcontainanynucleicacid.胞外形式：蛋白质，无核酸Infectious:causeanimalsdiseasesbovinespongiformencepha’lopathy(madcowHumanHumanCretzfeldt-JakobDiseaseMechanismofNeuronalcellsproducenormalprionprotein(PrPc)incell.Abnormallyfoldedprionprotein(PrPsc)cancatalyzerefoldingofPrPctoPrPsc.PrPscisproteaseresi