资源描述：
《武大英语考博阅读部分》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。
1、武汉大学阅读部分ReadingComprehensionText1Scientistshavegeneticallyengineeredtomatoandtobaccoplantstoproduceavaccineagainstthevirusthatcausessevereacuterespiratorysyndrome,orSARS,thediseasethatkillednearly800peoplein2003.Meanwhile,anotherteamofresearchershasdevelopedavaccinethatprotectsmonkeysagainstthedeadl
2、yEbolaandMarburgviruses,whichhaveplaguedcentralAfrica.AnongoingMarburgoutbreakinAngolahaskilledatleast357people.OnereasonitisdifficulttodevelopvaccinesfordiseaseslikeSARSandEbolaisbecausesomevirusesarebelievedtomutateconstantly.Ifaviruschangesquickly,avaccinemightbesuitableforawhilebutnotforever.Whi
3、lebothvaccinesarefarfromreadyforhumanuse,thestudiesraisethepossibilityofproducingeconomicalvaccinesfordiseasesforwhichthereisnoknowncure."Therewasaneedtopreparequicklyavaccinethatisinexpensiveandsafe,"saidHilaryKoprowski,whoisthedirectoroftheCenterforNeurovirologyatJeffersonMedicalCollegeinPhiladelp
4、hia,Pennsylvania.Healthofficialsalikehaveastrongneedforvaccinesthatarebotheconomicalandeasilyadministered.Plantshavelongbeenseenasanattractivesourceforvaccines,sinceplantscanbegrowninexpensivelyonalargescale.Theeasiestplanttogeneticallymodifyistobacco.FortheSARSstudy,Koprowskiandhiscolleaguesenginee
5、redlow-nicotineplantstoproduceaso-calledspikeproteinoftheSARSvirus.Theproteinisusedtotriggeranimmuneresponseinthehumanbody.OncetheresearchersshowedthattobaccocouldproducetheSARSvirusspikeprotein,theyappliedthesametechniquetotomatoes.Micethatwerefedgeneticallymodifiedtomatoesdevelopedantibodiestothev
6、irusthatcausesSARS.However,thescientistsdidnotreportwhethertheyinjectedthemicewiththeSARSvirus."Itdoesnotshowthattheantibodyoffersanyprotection,"saidMichaelLai,avirologistattheUniversityofSouthernCaliforniainLosAngeles.Don'texpecttosee"vaccinevegetables"anytimesoon.Researcherssayitwouldbeimpossiblet
7、ostandardizetheamountofvaccineinavegetable.Infactnovaccineproducedinplantshaseverbeenlicensedforhumanuse.However,thescientistsenvisionthattheSARSvaccinecouldbegroundintoapowder,formedintocapsules,andc
