冠狀病毒Coronavirusl論文-2012 Virus Taxonomy __ Coronaviridae.pdf

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1、PartII–ThePositiveSenseSingleStrandedRNAVirusesFamilyCoronaviridaeTaxonomicstructureofthefamilyFamilyCoronaviridaeSubfamilyCoronavirinaeGenusAlphacoronavirusGenusBetacoronavirusGenusGammacoronavirusSubfamilyTorovirinaeGenusTorovirusGenusBafinivirusDistinguishingfe

2、aturesThemembersofthefamilyCoronaviridae,amonophyleticclusterintheorderNidovirales,areenvel-oped,positivestrandedRNAvirusesofthreeclassesofvertebrates:mammals(corona-andtoro-viruses),birds(coronaviruses)andfish(bafiniviruses).Virionsarespherical,120–160nmacross(Co

3、ronavirinae),bacilliform,170–20075–88nm(Bafinivirus)orfoundasamixtureofboth,withbacilliformparticlescharacteristicallybentintocrescents(Torovirus).Theparticlesaretypicallydec-oratedwithlarge,club-orpetal-shapedsurfaceprojections(the“peplomers”or“spikes”),whichine

4、lectronmicrographsofsphericalparticlescreateanimagereminiscentofthesolarcorona.Thisinspiredthenameofthe“true”coronaviruses(nowgroupedinthesubfamilyCoronavirinae),whichwaslateradoptedforthewholefamily.Nucleocapsidsarehelicalandcanbereleasedfromthevirionbytreatmentw

5、ithdetergents.Whereasthecoronavirusnucleocapsidappearstobeloosely-wound,thoseoftheTorovirinaearedistinctivelytubular.Intermsofgenomesizeandgeneticcomplexity,theCoronaviridaearethelargestRNAvirusesiden-tifiedsofar,rivaledonlybytheokaviruses,largenidovirusesofinvert

6、ebratesassignedtothefam-ilyRoniviridae.Replicationhasbeenstudiedindetailonlyforcoronaviruses,butthelimiteddataavailablefortoro-andbafinivirusessuggestthatthelattervirusesuseessentiallysimilarstrategies.Virionsattachtodedicatedhostcellsurfacereceptorsviatheirspikes

7、(Table1)andreleasetheirgenomeintothetargetcellviafusionoftheviralenvelopewiththeplasmamembraneand/orthelimitingmembraneofanendocyticvesicle.Theentirereplicationcycletakesplaceinthecytoplasmandinvolvestheproductionoffull-lengthandsubgenome-sized(sg)minus-strandRNAi

8、nterme-diateswiththeviralgenomeservingbothasmRNAforthereplicasepolyproteinsandasatem-plateforminus-strandsynthesis.RNAsynthesisiscatalyzedbyanasyetpoorl