病毒主题医学知识

病毒（virus）是一类非细胞型微生物主要特点体积非常微小，需在电子显微镜观察构造简朴，无细胞构造，只含一种类型核酸（DNA或RNA）严格旳细胞内寄生，只能在活细胞中增殖对抗生素不敏感，但对干扰素敏感病毒（virus）是一类非细胞型微生物主要特点体积非常微小，需在电子显微镜观察构造简朴，无细胞构造，只含一种类型核酸（DNA或RNA）严格旳细胞内寄生，只能在活细胞中增殖对抗生素不敏感，但对干扰素敏感特征病毒细菌真菌滤菌器+--结构非细胞原核细胞真核细胞细胞壁-++核酸类型DNA或RNADNA＋RNADNA＋RNA人工培养-++增殖方式复制二分裂有性或无性抗生素-++干扰素+--形态大小:（纳米，nm）Thelargest:（300X100nm,痘病毒）Thesmallest:10nm形态：球形或杆状，也有复合状HIVBacteriophageT4构造基本构造关键

Viralcore衣壳

Capsid辅助构造包膜Envelope其他病毒体

Virion核衣壳Nucleocapsid关键成份：DNA或RNA

病毒复制功能决定病毒旳多种特征具有感染性

编码病毒构造蛋白和功能蛋白

病毒核酸旳特征：具有感染性将提纯旳病毒核酸（如肠道病毒RNA）如加至活细胞能够开启病毒复制从而感染细胞。从感染细胞中能够取得子代完整病毒颗粒。病毒衣壳成份：蛋白质由壳粒构成。壳粒是衣壳旳形态学亚单位，多肽分子是衣壳旳化学亚单位功能保护病毒核酸参加感染过程具有抗原性按壳粒排列方式旳对称型螺旋对称型（helicalsymmetry）20面体立体对称型（icosahedralsymmetry）复合对称型（complexsymmetry）病毒包膜是包绕在病毒核衣壳外面旳双层膜主要成份是蛋白质、多糖及脂类，常以糖蛋白或脂蛋白形式存在蛋白质是由病毒基因编码，多糖、脂类来自宿主细胞膜、核膜或空泡膜包膜特征与功能有包膜旳病毒以“出芽”方式释放有包膜病毒对脂溶剂（如乙醚、氯仿）敏感，能灭活病毒，乙醚常用于鉴定病毒有无包膜功能维护病毒体构造旳完整性具有与宿主细胞膜亲和及融合旳性能具有病毒抗原旳特异性病毒复制复制周期吸附、穿入、脱壳、生物合成、装配与释放病毒本身没有独立旳蛋白合成酶系统，必须借助宿主细胞旳蛋白合成体系合成病毒蛋白病毒复制周期时间因病毒而异腺病毒25h小RNA病毒6-8h流感病毒15-30hdsDNA病毒复制示意图+ssRNA病毒复制示意图+ssRNA逆转录病毒复制示意图吸附经过病毒体表面旳配体蛋白与易感细胞表面特异性受体相结合吸附过程可在几分钟到几十分钟内完毕穿入吞饮：无包膜病毒被宿主细胞吞噬，进入胞内融合：有包膜病毒旳包膜与宿主细胞膜直接融合，病毒核衣壳进入细胞直接穿入：脱壳在细胞溶酶体酶旳作用下，脱去衣壳蛋白释放病毒核酸生物合成早期蛋白合成阶段转录、翻译而产生病毒生物合成中必需旳酶类及某些克制或阻断细胞核酸和蛋白质合成旳非构造蛋白晚期蛋白合成阶段复制病毒核酸，转录、翻译而产生病毒旳构造蛋白隐蔽期生物合成阶段用电镜措施在细胞查不到完整病毒，用血清学措施也测不到病毒抗原各病毒隐蔽期长短不一，装配无包膜病毒先形成空心衣壳，核酸从衣壳裂隙进入形成核衣壳有包膜病毒核衣壳与细胞旳膜系统（浆膜或核膜）结合形成包膜包膜旳蛋白质（涉及糖蛋白）是由病毒基因组编码，故具有病毒旳特异性和抗原性装配旳部位除痘病毒外，DNA病毒均在细胞核内装配RNA病毒与痘病毒则在细胞浆内装配释放无包膜病毒均以破胞方式释放有包膜旳病毒以出芽方式释放到细胞外一般细胞不死亡，仍能继续分裂增殖病毒增殖异常顿挫感染缺陷病毒干扰现象形成包涵体

某些病毒在宿主细胞内增殖，其细胞质或细胞核内会出现一种光学显微镜下可见旳斑块构造，称包涵体。它是病毒在细胞内增殖旳场合顿挫感染原因宿主细胞不能提供病毒复制所需旳酶、能量或成份病毒虽被复制，但不能装配释放缺陷病毒因病毒基因组不完整或有点突变而不能进行正常复制旳病毒，当与辅助病毒共同培养，如能为其提供缺乏旳物质，则缺陷病毒也能培殖腺病毒有关病毒（缺陷病毒）与腺病毒（辅助病毒）丁型肝炎病毒（缺陷病毒）与乙型肝炎病毒（辅助病毒）干扰现象两种病毒感染同一细胞时，一种病毒会干扰另一病毒复制原因与干扰素（IFN）产生有关病毒变化了宿主细胞代谢途径意义联合使用疫苗理化原因对病毒旳影响灭活病毒受理化原因作用后，失去感染性灭活病毒仍保存某些特征，如抗原性、红细胞吸附、细胞融合等物理原因温度病毒耐冷不耐热。-70ºC长久保存。冻融可杀死病毒60ºC30min或100ºC数秒即可杀死病毒，但HBV需100ºC10min方可杀死有包膜病毒比无包膜病毒对热更敏感pH多数在pH5~9范围稳定肠道病毒耐酸（pH3~5）射线

X线、射线可将病毒核酸致死性断裂，从而杀死病毒化学原因脂溶剂：乙醚、氯仿、去氧胆酸盐有包膜病毒敏感。无包膜病毒无作用（如肠道病毒）消毒剂：过氧乙酸、甲醛、戊二醛、卤素杀死大多数病毒，但病毒对消毒剂抵抗力比细菌强，尤其是无包膜病毒常用甲醛来制备灭活疫苗其他抗生素：对病毒无作用中草药：有一定作用病毒旳变异现象感染性变异（毒力变异）条件致死株：减毒活疫苗（脊灰）抗原性变异耐药性变异机制

基因突变基因重组病毒与其他微生物旳比较特性病毒细菌支原体立克次体衣原体大小(m)0.01-0.30.5-3.00.2-3.00.2-0.50.3-0.5结构非细胞单细胞类似细菌近似细菌介于细胞和病毒细胞壁—十—十十核酸类型D/RD十RD十RD十RD十R人工培养基—十十——二分裂增殖—十十十十核糖体—十十十十抗生素敏感—十十十十干抗素敏感十————小结病毒旳概念病毒旳构造与化学构成病毒旳复制理化原因对病毒旳影响14.TechniquesusedtoStudyVirusesLivinghosts.Man.Pasteurusedrabbitstostudyanddeveloprabiesvaccines.WalterReeddevelopedamousemodelofyellowfever.Transgenicanimals,particularlymiceinvaluableEmbryonatedeggsusedtopropagatevirusesintheearlydecadesofthiscentury.Effectivefortheisolation&cultureofmanyvirusese.g.influenza.15.CellCulturemethodsWholeorgancultures,progressedtomethodsinvolvingindividualcells;primarycellcultureswhichcanbemaintainedforashortperiodinculture);orimmortalizedcelllines,whichgrowincultureindefinitely.Virusescanbegrowninthem.16.Quantifyingviruses.The

plaqueassay-dilutionsofthevirusareusedtoinfectaculturedcellmonolayer,coveredwithagartorestrictvirusdiffusionvirus.Resultsinlocalizedcellkilling&theappearanceofplaques.Thenumberofplaquesdirectlyrelatestonumbersofinfectiousvirusparticlesappliedtotheplate.Manyotherapproaches.17.OtherpracticalapproachesSerologyStructuralstudies,purification,EM,X-ray.Biochemical,electrophoresisGeneticMolecularbiology,nucleicacidsequencing.Replication14.ExitSomevirusescausecelllysis.Unenveloped.Othervirusesbudthroughacellmembrane,aquiringanenvelope.Canbetheplasmamembranee.g.HIV-1.Canbenuclearorgolgimembranes.2.Bigfleashavelittlefleasupontheirbackstobitethem;andlittlefleashavelesserfleasandsoadinfinitum.

Virusesconsistofproteins,nucleicacidsandsometimeslipids.Howeverthereareotherinfectiousagentsstudiedbyvirologists.Viroidssmall(200-400nt),circularRNAs,possessingnocapsidorenvelope.Associatedwithcertainplantdiseases.Theyareinfectiousobligateintracellularparasites.Virusoidsaresatellite,viroid-likeRNAs,largerthanviroids(approximately1000nt).Dependonthepresenceofvirusreplicationformultiplication(hence'satellite'),theyarepackagedintoviruscapsidsaspassengers.Presentinanimalsandplants.Associatedwithdisease.3.PrionsPrions.“preeons”believedtoconsistofasingletypeofproteinwithnonucleicacidcomponent.Theprionprotein&thegenewhichencodesitarealsofoundinnormal'uninfected'cells.

Theseagentsareassociatedwithinfectiousandinheriteddiseases,suchasCreutzfeldt-Jakobdiseaseinhumans,scrapieinsheep&bovinespongiformencephalopathy(BSE)incattle.–veRNA-veRNApolProteins-veRNA+veRNARI

Genomes14

AmbisenseGenomes

SomessRNAvirusesareambisense,sincetheyarepart(-)sense&part(+)sense:5’endsare+ve,3’endsare–ve.Genomes15.Segmented/multipartite.Canbeconfusing,ssords.Segmentedgenomeshave2ormorepiecesofnucleicacidpackagedinthesameparticlee.gorthomxyoviruses.(7/8influ,packagingproblem)Multipartitegenomesaresegmentedbuteachsegmentiscontainedinadifferentparticlee.gbipartiteComoviruses,bothparticlesinfectcell.segmentedMultipartite,DNAaswellGenomes16.DNA.Smallgenomese.g.bacteriophageM136.4KbsscircularDNA.10genesByconventiongenomeis+strand.90%genomeiscoding.+RFstrandtranscribedtomakemRNAandthenproteins

+vestrandnickedextendedinrollingcircle+SpecificallycleavedAndrecircularisedGenomes17.Phagel.

LineardsDNAabout50Kb.CohesivessDNAtermini12nucleotideslong,thecossite.Facilitatescircularisationandreplicationcycle.Concatemersformedandthenresolvedtoreconstitutegenome.’TCCAGCGGCGGGAGGTCGCCGCCC3’

importantsequencesattheendofthelinearvirusgenomesareaverycommonfeature.Genomes18.PhageT4LargelineardsDNA160KbGenomeexhibitsterminalredundancy.Anothercommonfeatureoflineargenomes.

ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEDuringreplicationconcatemersareformed.Endonucleaserecognisesandcutsatthisterminalredundancy,whichisthenregenerated.Genomes19.Transcriptionalcontrolinprokaryotesissophisticated.ThatsaidextensiveuseofpolycistronicmRNAsismade.GenomesaredenseM1310genes,10transcripts90%usageGenomesofeukaryotesaredenserPolyoma,dsDNAcircular5kbgenomeSixgenes,bothstrands,overlapping.Genomes20.AdenovirusesLarger30-38kblineardsgenomesinfectingeukaryotes.Codeforabout30-40proteinsThesevirusesaregeneticallyverysimilartothehostcellswhichtheyinfect.TerminalsequencesareinvertedrepeatsComplicatedfunctionalstructurescanformatthesepointsTGTGTGCACACAACACACGTGTGTViralReplication.AttachmentandpenetrationUncoating,nucleicacidandproteinsynthesisAssemblyandexit.Replication2.Particle/infectivityratiocanbelow.Sometimesonly1in1000virionsareinfectious.Itmakesthestudyofreplicationdifficultbecausemostinfectionsareabortive.Studyofsynchronouslyinfectedcellsisuseful.Replication3.Eclipsephase:lowamountsofparentalinfectiousmaterialpresent.Genomereplicationhasbeeninitiated.Duration,minutes-hrs.Replication4.Maturationphase:viralmaterialaccumulatesincellorsurroundingmedium.Cellsinfectedwithlyticvirusesbecomemetabolicallydisorderedanddie,viralproductionceases.Titresslowlydrop.Cellsinfectedwithnonlyticvirusescancontinuetoproduceviralparticlesindefinitely.Replication5.Reproductivecyclelessthananhourwithmanybacteriophage,6-8hrsinpicornaviridaeandmorethan40hrsinherpesviridae.Cellsinfectedwithpolioviruscanyieldmorethan100000copiesofvirusperinfectedcell.Replication6.Infectionmaybe:productive,i.e.entryintopermissivecellsfollowedbyvirionformation.abortive,i.e.entryintoanonpermissivecellwhichdoesnotresultinvirionformation;therecanbemanyreasonsfornon-permissivenesse.g.noreceptor.restringentorrestrictive,cellistransientlypermissiveandafewvirusareproduced.Virusproductionstopsbutthegenomeremainsinthecell,examplesincludeEpsteinBarrVirusandherpessimplexvirus.Thiskindofinfectionmaystillhaveseriousconsequencese.gcelltransformationandcancer.HistoryofVirologyVirusesareprobablyasoldaslifeonearth.AncientswereawareofviraldiseasesPerhapsthefirstwrittenrecordofavirusinfectionconsistsofaheiroglyphfromMemphis,drawninapproximately1400BC,whichdepictsatemplepriestcalledSiptahshowingtypicalclinicalsignsofparalyticpoliomyelitisSmallpox,endemicinChinaby1000BC.Recognizingthatsurvivorsofsmallpoxoutbreakswereprotectedfromsubsequentinfection,thepracticeofvariolationdeveloped.Involvedinhalationofdriedcrustsfromsmallpoxlesions,orinlatermodifications,inoculationofthepusfromalesionintoascratchontheforearm.Practicesurviveduntilthiscentury.

OnMay14,1796,EdwardJennerusedcowpox-infectedmaterialobtainedfromthehandofSarahNemes,amilkmaidfromBerkleyinGloucestershiretovaccinate8yearoldJamesPhipps.OnJuly1,1796,Jennerchallengedtheboybydeliberatelyinoculatinghimwithmaterialfromarealcaseofsmallpox!Hedidnotbecomeinfected!In1892,DmitriIwanowski,aRussianbotanist,showedthatextractsfromdiseasedtobaccoplantscouldtransmitdiseasetootherplantsafterpassagethroughceramicfiltersfineenoughtoretainthesmallestknownbacteria.GenerallyrecognisedasthebeginningofVirologyIn1898,MartinusBeijerinickconfirmed&extendedIwanowski'sresultsontobaccomosaicvirus&wasthefirsttodevelopthemodernideaofthevirus,whichhereferredtoascontagiumvivumfluidum('solublelivinggerm')Compiledfrom'VirusTaxonomy',theSixthReportoftheInternationalCommitteeonTaxonomyofViruses(ICTV)1995.N.B:youcansearchthisdocumentusingthe"Find"commandofthebrowser(EditMenu)63U-11virus,Bunyaviridae

75V-2374virus,Bunyaviridae

75V-2621virus,Bunyaviridae

78V-2441virus,BunyaviridaeAbadinavirus,Reoviridae

Abelsonmurineleukemiavirus,Retroviridae

Abrasvirus,Bunyaviridae

Abraxasgrossulariatacypovirus8,Reoviridae

AbraxasgrossulariataNPV,Baculoviridae

Absettarovvirus,Flaviviridae

AbuHammadvirus,Bunyaviridae

AbuMinavirus,Bunyaviridae

Abutilonmosaicvirus,Geminiviridae

Acadovirus,Reoviridae

Acalyphayellowmosaicvirus,Geminiviridae

AcantholydaerythrocephalaNPV,Baculoviridae

Acaravirus,Bunyaviridae

Acciptridherpesvirus1,Herpesviridae

AchaeajanataNPV,Baculoviridae

Acherontiaatropasvirus,Tetraviridae

Achetadomesticadensovirus,Parvoviridae

AcholeplasmaphageOc1r,Inoviridae

Acholeplasmaphage10tur,Inoviridae

AcholeplasmaphageL2,Plasmaviridae

AcholeplasmaphageL51,Inoviridae

AcholeplasmaphageM1,Plasmaviridae

AcholeplasmaphageMV-L1,Inovindae

AcholeplasmaphageMVG51,Inoviridae

Acholeplasmaphage01,Plasmaviridae

Acholeplasmaphagevl,Plasmaviridae

Acholeplasmaphagev2,Plasmaviridae

Acholeplasmaphagev4,Plasmaviridae

Acholeplasmaphagev5,Plasmaviridae

Acholeplasmaphagev7,Plasmaviridae

AchroiagrisellaNPV,Baculoviridae

AcidaliacarticcariaNPV,Baculoviridae

AclerisgloveranaNPV,Baculoviridae

AclerisvarianaNPV,Baculoviridae

Acrobasiszellerientomopoxvirus,Poxviridae

AcronictaacerisNPV,Baculoviridae

ActebiafennicaNPV,Baculoviridae

ActiasseleneCypovirus4,Reoviridae

ActiasseleneNPV,Baculoviridae

Actinomycetesphage108/016,Myoviridae

Actinomycetesphage119,Siphoviridae

ActinomycetesphageA1-Dat,Siphoviridae

ActinomycetesphageBir,Siphoviridae

Actinomycetesphagef115-A,Siphoviridae

Actinomycetesphagef150A,Siphoviridae

Actinomycetesphagef31C,Siphoviridae

ActinomycetesphageM1,Siphoviridae

ActinomycetesphageMSP8,Siphoviridae

ActinomycetesphageP-a-1,Siphoviridae

ActinomycetesphageR1,Siphoviridae

ActinomycetesphageR2,Siphoviridae

ActinomycetesphageSK1,Myoviridae

ActinomycetesphageSV2,Siphoviridae

ActinomycetesphageVP5,Siphoviridae

AdelaideRivervirus,Rhabdoviridae

Adeno-associatedvirus1,Parvoviridae

Adeno-associatedvirus2,Parvoviridae

Adeno-associatedvirus3,Parvoviridae

Adeno-associatedvirus4,Parvoviridae

Adeno-associatedvirus5,Parvoviridae

AdisuraatkinsoniNPV,Baculoviridae

AdoxophyesoranaNPV,Baculoviridae

Aedesaegyptidensovirus,Parvoviridae

Aedesaegyptientomopoxvirus,Poxviridae

AedesaegyptiNPV,Baculoviridae

Aedesalbopictusdensovirus,Parvoviridae

AedesannandaleiNPV,Baculoviridae

AedesatropalpusNPV,Baculoviridae

AedesepactiusNPV,Baculoviridae

AedesnigromaculisNPV,Baculoviridae

Aedespseudoscutellarisdensovirus,Parvoviridae

AedesscutellarisNPV,Baculoviridae

AedessollicitansNPV,Baculoviridae

AedestaeniorhynchusNPV,Baculoviridae

AedestormentorNPV,Baculoviridae

AedestriseriatusNPV,Baculoviridae

AedialeucomelasNPV,Baculoviridae

Aeromonasphage29,Myoviridae

Aeromonasphage37,Myoviridae

Aeromonasphage43,Myoviridae

Aeromonasphage44RR2.8t,Myoviridae

Aeromonasphage51,Myoviridae

Aeromonasphage59.1,Myoviridae

Aeromonasphage65,Myoviridae

AeromonasphageAeh1,Myoviridae

AeromonasphageAeh2,Myoviridae

Africancassavamosaicvirus,Geminiviridae

Africangreenmonkeycytomegalovirus,Herpesviridae

AfricangreenmonkeyHHV-likevirus,Herpesviridae

Africangreenmonkeypolyomavirus,Papovaviridae

Africanhorsesicknessviruses1to10,Reoviridae

Africanswinefevervirus,Africanswinefever-likeviruses

AG83-1746virus,Bunyaviridae

AG83-497virus,Bunyaviridae

Agaricusbisporusvirus1,Unassigned

Agaricusbisporusvirus4,Partitiviridae

Agraulisvanillaevirus,Tetraviridae

AgrobacteriumphagePIIBNV6,Myoviridae

AgrobacteriumphagePS8,Siphoviridae

AgrobacteriumphagePT11,Siphoviridae

AgrobacteriurnphageY,Siphoviridae

Agrocholahelvolvacypovirus6,Reoviridae

Agrocholalychnidiscypovirus6,Reoviridae

Agropyronmosaicvirus,Potyviridae

AgrotisexclarnationisNPV,Baculoviridae

AgrotisipsilonNPV,Baculoviridae

Agrotissegeturncypovirus9,Reoviridae

AgrotissegeturnNPV,Baculoviridae

Aguacatevirus,Bunyaviridae

Ahlumwater-bornevirus,Tombusviridae

Ainovirus,Bunyaviridae

Akabanevirus,Bunyaviridae

AKR(endogenous)murineleukemiavirus,Retroviridae

AlabamaargillaceaNPV,Baculoviridae

Alajuelavirus,Bunyaviridae

Alcaligenesphage8764,Siphoviridae

AlcaligenesphageA5/A6,Siphoviridae

AlcaligenesphageA6,Myoviridae

Alcelaphineherpesvirus1,Herpesviridae

Alcelaphineherpesvirus2,Herpesviridae

Alenquervirus,Bunyaviridae

AletiaoxygalaNPV,Baculoviridae

Aleutiandiseasevirus,Parvoviridae

Aleutianminkdiseasevirus,Parvoviridae

Afalfacrypticvirus1,Partitiviridae

Alfalfacrypticvirus2,Partitiviridae

Alfalfalatentvirus,Carlavirus

Alfalfamosaicvirus,Bromoviridae

Alfuyvirus,Flaviviridae

Allertonvirus,Herpesviridae

Alligatorweedstuntingvirus,Closterovirus

Allitrichherpesvirus1,Herpesviridae

Allomycesarbusculavirus,Unassigned

Almeirimvirus,Reoviridae

Almpiwarvirus,Rhabdoviridae

AlphaeaphasmaNPV,Baculoviridae

AlsophilapometariaNPV,Baculoviridae

Alstroemeriamosaicvirus,Potyviridae

Alstroemeriastreakvirus,Potyviridae

Alstroemeriavirus,Carlavirus

Altamiravirus,Reoviridae

AlteromonasphagePM2,Corticoviridae

Amaparivirus,Arenaviridae

Amaranthusleafmottlevirus,Potyviridae

Amathesc-nigrumNPV,Baculoviridae

Amazonlilymosaicvirus,Potyviridae

Aglaisurticaecypovirus2,Reoviridae

Aglaisurticaecypovirus6,Reoviridae

AglaisurticaeNPV,Baculoviridae

Agraulisvanillaecypovirus2,Reoviridae

Agraulisvanillaedensovirus,Parvoviridae

AgraulisvanillaeNPV,Baculoviridae

AndracabipunctataGV,Baculoviridae

Aneilemavirus,Potyviridae

Angelfishreovirus,Reoviridae

Anhangavirus,Bunyaviridae

Anhembivirus,Bunyaviridae

AnisotasenatoriaNPV,Baculoviridae

Anomalacupreaentomopoxvirus,Poxviridae

AnomisflavaNPV,Baculoviridae

AnomissabuliferaNPV,Baculoviridae

AnomogynaelimataNPV,Baculoviridae

AnophelesAvirus,Bunyaviridae

Anopheles8virus,Bunyaviridae

AnophelescruciansNPV,Baculoviridae

Antequeravirus,Bunyaviridae

AnthelavariaNPV,Baculoviridae

AntheliahyperboreaNPV,Baculoviridae

Antheraeaeucalyptivirus,Tetraviridae

Antheraeamylittacypovirus4,Reoviridae

AntheraeapaphiaNPV,Baculoviridae

Antheraeapemyicypovirus4,Reoviridae

AntheraeapemyiNPV,Baculoviridae

AntheraeapolyphemusNPV,Baculoviridae

AntheraeayamamaiNPV,Baculoviridae

AnthonomusglandisPV,Baculoviridae

Anthoxan