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1、PartVIIIViruspersistentinfectionSectionITypeofinfectionSectionIIThemechanismofpersistentinfectionpersistentinfectionlatentinfectionchronicinfectionslowvirusinfectionSectionIIExampleofpersistentinfectionI.HepatitisBvirus,HBV乙型肝炎病毒1.Biologicalpropertiesamemberofthehepadnaviru
2、sfamilyacircular,partiallydouble-strandedDNA,aprimerprotein,andaviral-specificDNApolymeraseassociatedwiththeDNA.complexvirionstructure.thevirion,alsocalledthedaneparticle,is42nmindiameter.stableat-20℃andsensitivetohighertemperature(100℃for1minute)HBVgenomeorganizationtwounev
3、enstrandsofDNA:(-)sensestrand:3.0-3.3kb(+)sensestrand:1.7-2.8kbBaruchBlumberg,1963:‘Australianantigen-Au'.1967:Auwasaviralantigen=HBsAg(surfaceantigen)Dane,1970:Discovered42nm'Daneparticles‘HBcAg(coreantigen).1973:HBeAgdiscovered(endogenousantigen=atruncatedversionofHBcAg).s
4、ecretedfilamentsecretedspherehepatitisBvirion2.TheHBVlifecycle3.Clinicalfindings3.1acuteinfection:symptomsduringtheprodromalperiodmayincludefever,yellowjaundice.Theclassicictericsymptomsofliverdamagefollowsoonthereafter.recoveryisindicatedbyadeclineinthefeverandrenewedappeti
5、te.AcuteViralHepatitisSource:CDC3.2chronicinfection:chronichepatitisoccursin5%to10%ofpeoplewithHBVinfections,usuallyaftermildorinapparentinitialdisease.itmaybedetectedonlybyfindingelevatedliverenzymelevelsonaroutinebloodchemistryprofile,butasmanyas10%ofpatientswithchronichep
6、atitismaydevelopcirrhosis,primaryhepatocellularcarcinoma国人感染HBV起始于围产或幼龄期幼龄感染成年感染90%慢性化10%清除病毒急性肝炎<1%暴发肝炎非活动性携带慢性肝炎(HBeAg-)(HBeAg+/-)40%肝硬化95%清除病毒5%慢性感染非活动性携带慢性肝炎(HBeAg)(HBeAg+/)15~20%肝硬化4.LaboratorydiagnosisThedetectionofHBeAgisthebestcorrelatetothepresenceofinfectiousvirus.
7、AchronicinfectioncanbedistinguishedbythecontinutedfindingofHBeAg,HBsAg,orbothandalackofdetectableantibodytotheseantigens.Duringthesymptomaticphaseofinfection,detectionofantibodiestoHBeAgandHBsAgisobscuredbecausetheantibodyiscomplexedwithantigenintheserum.thebestwaytodiagnose
8、arecentacuteinfection,especiallyduringtheperiodwhenneitherHBsAgnoranti-HBsc