交大微生物課件interactions with humans

Intimatestrangers:MicroorganismsinandonLecture17-Human-Microbe Chapter21BROCKBIOLOGYOFShanghaiJiaoTongUniversityII.Harmful ctionswithHowcanapathogencauseShanghaiJiaoTongInfectionandInfection:ThegrowthofmicroorganismsinthehostDisease:ThedamageorinjurytothehostthatimpairshostfunctionInfectionisnotsynonymouswithdisease ShanghaiJiaoTongPathogensTheabilityoftheparasitetoinflictdamageonthe(susceptibility抗性/Theabilityofthehosttoberesistanttothe tativemeasureofpathogenicity:CellorviralnumberthatwillelicitapathogenicresponseinahostinagivenperiodMicroorganismsandpathogenesis.Microorganismsandpathogenesis.Thepresenceandevengrowthofmicroorganismsonthehostdoesnotalwaysleadtodisease微生物存在或生ShanghaiJiaoTongAdherenceand Specificity特異性/Bacteriaor esabletoinitiateinfectionoftenadherespecificallytocells(tissuespecificityandhostspecificity)通過特異性吸附完成 Mechanism:protein-proteinin ctiononthesurfacesofthepathogenandthehostcell.機理表ShanghaiJiaoTongAdherenceandInvasionReceptorsonthesurfaceofhostMacromoleculesonthesurfaceofCapsuleGlycocalyx胞外糖蛋FimbriaePili 因子ShanghaiJiaoTongColonizationandGrowth定植與生長Colonization:MultiplicationinhostOrganicTraceelements-irontransferrinandSiderophores,bactinencodedbyCol EnvironmentalReductionShanghaiJiaoTongLocalizationinthe LocalizedTheboil,carbuncle,orpimplethatcommonlyarisesfromStaphylococcusinfectionsoftheskin.癤,癰,丘疹由葡萄球GeneralizedBacteremia:ifextensivebacterialgrowthintissuesoccurs,someoftheorganismsareusuallyshedintothebloodstreaminlargenumbers.菌血癥ShanghaiJiaoTongVirulenceVirulencetherelativeabilityofaparasitetocausedisease(figure)Lethaldose50(LD50):thedoseofanagentthatkills50%oftheanimalsinatestgroup.半致死劑量Lostvirulence:attenuated減毒Toxicitytheabilityofanorganismtocausediseasebymeansofapreformedtoxinthatinhibitshostcellfunctionorkillshostcells.毒Invasiveness:theabilityofanorganismtogrowinhosttissueinsuchlargenumbersthatthepathogeninhibitshostfunction.侵染III.VirulenceFactorsandShanghaiJiaoTongVirulencefactorsExtracellularproteinsproducedbythepathogentoaidintheestablishmentandmaintenanceofdisease胞外酶的作用Hyaluronidase透明質(zhì)酸酶)breakdownhyaluronicacid-thetissuecementinanimalsProteases,nucleases,lipasestoproduceCollagenase膠原酶todissolvetissueStreptokinase溶栓酶todissolvefibrinCoagulase凝固酶toprotectpathogenwithfibrinExample:Example:VirulencefactorsinShanghaiJiaoTongExotoxins外毒Exotoxins-Extracellularproteins,maytravelfromafocusofinfectiontodistantpartsofthebodyandcausedamageinregionsfarremovedfromthesiteofmicrobialgrowth. ShanghaiJiaoTongThreeCategoriesofActoncellmembraneandcausecellA-BBcomponentbindstoreceptorsonthecellAcomponentgetintothecelltodoInducemassiveorevensystemic toryreactionsstimulatinglargenumbersofimmuneresponsecells可通過刺激ShanghaiJiaoTongEnterotoxins-Exotoxinsthatactonthesmallintestinetocausevomitinganddiarrhea作用于小腸而致 Choleraenterotoxincomplexglycolipid)intheepithelialcellA-BBforAforactivationofthecellularenzyme,cyclasetocauseconversionofATP-CholeraActionActionofcholeraThenormalprocessofmovementintheColonizationVibriocholeraebindingofenterotoxinwiththeGM1gangliosideonhostcellsTheA-BtoxinactsbyinternalizingthetoxicAcomponentandactivatingadenylcyclase.ofnormalsodium(Na+)LossofH2Ointothelumen,andShanghaiJiaoTonglipopolysaccharidesintheouterlayerofcellwallofGram-negativebacteriatheyaregenerallycell-boundandreleasedinlargeamountsonlywhencellsarelysed.內(nèi)毒素：G-細菌的胞壁外膜的脂多糖，ShanghaiJiaoTongEndotoxins:ModeofFeverinduction:Stimulatehostcelltoreleaseendogenouspyrogenst