近日，BBC报道了一项研究：来自诺福克的约翰·英纳斯中心（JohnInnesCentre，inNorfolk）的团队利用一种类似烟草的植物，使脊髓灰质炎疫苗研究获得了突破性进展。
这种疫苗是一种模拟脊髓灰质炎病毒的病毒样颗粒，病毒样颗粒是一种不含核酸的空心病毒颗粒，形态结构上与天然病毒颗粒极其相似。它具有免疫原性，但无法复制，因此不具有感染性。
科学家们巧妙利用了这种烟草属植物新陈代谢的一部分，使它的叶子变成脊髓灰质炎疫苗“工厂”。设计思路是将编码脊髓灰质炎病毒的外壳的
遗传密码与自然中感染植物的病毒的某些元件结合在一起以增强其功能；随后该遗传密码子被导入土壤细菌中，这些细菌再被用来感染烟草；感染成功后，植物识别了脊灰病毒的遗传密码，开始制造病毒样颗粒；被感染的叶片加入水中、混合，再提取脊髓灰质炎疫苗。
动物实验显示：这种病毒样的粒子阻止了小儿麻痹症，对其3D结构的分析表明其与脊髓灰质炎病毒几乎完全相同。
该病毒样颗粒图像，由DiamondLightSource电子生物成像中心提供
来自约翰·英纳斯中心（JohnInnesCentre）GeorgeLomonossoff教授认为，这是一个很有前途的技术，他希望能在不远的将来可以在植物中生产疫苗。
据悉，这项研究作为寻找脊髓灰质炎疫苗替代品的一部分，由世界卫生组织（WorldHealthOrganization）资助。尽管在世界上大部分地区脊灰病毒得到控制，但感染还没有根除。
研究者还表示，这种技术并不局限于脊髓灰质炎，甚至不仅局限于疫苗。只要研究人员有正确的遗传密码序列，他们就可以研制出针对大多数病毒的疫苗。他们还用植物制造抗体，就像
癌症治疗中的抗体一样。
植物有生长迅速的优势，只需要阳光、土壤、水和二氧化碳才能生长。这意味着植物造疫苗或成为疫苗开发的廉价和低技术的解决方案。但仍有一些问题需要解决，如何大规模生产疫苗。另一个问题是，使用植物制造疫苗是否有风险——用烟草相关的植物制造的疫苗中含有尼古丁吗？
几乎没有在植物中生产人类疫苗的先例，南威尔士大学（UniversityofSouthWales）的生物技术教授DenisMurphy表示，这是一个重要的成就，现在的挑战是优化植物表达系统，并转向新疫苗的临床试验。
BBC原文报道：
Plantshavebeen"hijacked"tomakepoliovaccineinabreakthroughwiththepotentialtotransformvaccinemanufacture,sayscientists.TheteamattheJohnInnesCentre,inNorfolk,saystheprocessischeap,easyandquick.
Aswellashelpingeliminatepolio,thescientistsbelievetheirapproachcouldhelptheworldreacttounexpectedthreatssuchasZikavirusorEbola.Expertssaidtheachievementwasbothimpressiveandimportant.Thevaccineisan"authenticmimic"ofpolioviruscalledavirus-likeparticle.
Outwardlyitlooksalmostidenticaltopoliovirusbut-likethedifferencebetweenamannequinandperson-itisemptyontheinside.Ithasallthefeaturesneededtotraintheimmunesystem,butnoneoftheweaponstocauseaninfection.
Leafyfactory
Thescientistshijackedarelativeofthetobaccoplant'
smetabolismtoturnitsleavesintopolio-vaccine"factories".First,theyneededtocreatenewinstructionsfortheplanttofollow.Thestartingmaterialwasthegeneticcodeformakingtheoutersurfaceofpoliovirus.Itwasenhancedbycombiningitwithmaterialfromvirusesthatnaturallyinfectplants.Thenewinstructionswerethenputintosoilbacteria,whichwereusedtoinfecttobacco.Theinfectiontookhold,theplantsreadthegeneticinstructionsandstartedmakingthevirus-likeparticles.
Infectedleavesweremixedwithwater,blended,andthepoliovaccinewasextracted.
Thevirus-likeparticlespreventedpolioinanimalexperiments,andananalysisoftheir3Dstructureshowedtheylookedalmostidenticaltopoliovirus.
ProfGeorgeLomonossoff,fromtheJohnInnesCentre,toldtheBBCNewswebsite:"Theyareincrediblygoodmimics."It'saverypromisingtechnology,
"Iwouldhopewegetvaccinesproducedinplantsinthenottoodistantfuture."
TheresearchisfundedbytheWorldHealthOrganization,aspartofeffortstofindreplacementsforthepoliovaccine.
Polio-whichcancausepermanentparalysis-isathingofthepastformostoftheworld,buttheinfectionhasnotbeeneradicated.Andusingweakenedpoliovirusincurrentvaccinesposesariskofthevirusregainingsomeofitsdangeroustraits-calledvaccine-derivedpoliovirus.
DrAndrewMacadam,principalscientistattheUK'sNationalInstituteforBiologicalStandardsandControl,said:"Currentvaccinesforpolioareproducedfromlargeamountsoflivevirus,whichcarriesathreatofaccidentalescapeandre-introduction."Thisstudytakesusastepclosertoreplacingcurrentpoliovaccines,providinguswithacheapandviableoptionformakingvirus-likeparticle-basedvaccines."
Greatpotential
Butthistechnologyisnotlimitedtopolioorevenjusttovaccines.
Aslongasresearchershavetherightsequenceofgeneticcode,theycanmakeavaccineagainstmostviruses.Andtheyhavealsousedplantstomakeantibodieslikethosebeingusedincancertherapy.
Plantsarealsobeinginvestigatedasanewsourceforthewinterflujab.
Currently,itisgrowninchickeneggsandtakesmonthstodevelop.
ProfLomonossofftoldtheBBC:"InanexperimentwithaCanadiancompany,theyshowedyoucouldactuallyidentifyanewstrainofvirusandproduceacandidatevaccineinthreetofourweeks.
"Ithaspotentialformakingvaccinesagainstemergingepidemics,ofcourserecentlywehadZikaandpriortothatwehadEbola."It'shighlyresponsive,andthat'soneofthegreatattractionsofthetechnology."Theplantshavetheadvantageofgrowingquicklyandneedingonlysunlight,soil,waterandcarbondioxidetogrow.
Itmeansitcouldbeacheapandlow-techsolutiontovaccinedevelopment.
Buttherearestillissuestoresolve,includingmakingvaccineonalargescale.
Anotherissueiswhetherthereisanyriskfromusingplantstomakethevaccine-doesthetobacco-relativemeanthereisnicotineinthevaccine?
DrTaritMukhopadhyay,alecturerinvaccinedevelopmentatUniversityCollegeLondon,said:"Theinitialresultslookimpressive."However,thereareveryfewplant-basedvaccinemanufacturersandalmostnolicensedhumanvaccinesthatarecurrentlyproducedinplants."DenisMurphy,aprofessorofbiotechnologyattheUniversityofSouthWales,said:"Thisisanimportantachievement."Thechallengeisnowtooptimisetheplantexpressionsystemandtomovetowardsclinicaltrialsofthenewvaccine."
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