千里之行，始于足下。第2頁/共2頁精品文檔推薦醫(yī)學考博英語翻譯訓練題醫(yī)學考博英語翻譯訓練題：艾滋之謎揭曉

AnAIDSMysterySolved

（1）About15yearsago，awell－meaningmandonatedbloodtotheRedCrossinSydney，Australia，notknowinghehasbeenexposedtoHIV－1，thevirusthatcausesAIDS．Muchlater，public－h(huán)ealthofficialslearnedthatsomeofthepeoplewhogottransfusions？containinghisbloodhadbecomeinfectedwiththesamevirus；presumablytheywerealmostsuretodie．Butassixyearsstretchedto10，thento14，theanxietyofhealthofficialsgavewaytoastonishment．Althoughtwooftherecipientshavediedfromothercauses，notoneofthesevenpeopleknowntohavereceivedtransfusionsoftheman’scontaminatedbloodhascomedownwithAIDS．Moretellingstill，thedonor，asexuallyactivehomosexual，isalsohealthy．InfacthisimmunesystemremainsasrobustasifhehadnevertangledwithHIVatall．Whatcouldexplainsuchunexpectedgoodfortune？

（2）AteamofAustralianscientistshasfinallysolvedthemystery．Thevirusthatthedonorcontractedandthenpassedon，theteamreportedlastweekinthejournalScience．containsflawsinitsgeneticscriptthatappeartohaverendereditinnocuous？．“Notonlyhavetherecipientsandthedonornotprogressedtodiseasefor15years，”marvelsmolecularbiologistNicholasDeaconofAustralia’sMacfarlaneBurnetCentreforMedicalRe－search，“butthepredictionisthattheyneverwill．”Deaconspeculatesthatthis“impotent”HIVmayevenbeanaturalinoculant？thatprotectsitscarriersagainstmorevirulentstrains？ofthevirus，muchasinfectionwithcowpoxwardedoffsmallpoxin18th－centurymilkmaids．

（3）Ifthis______provesright，itwillmarkamilestoneinthebattletocontainthelate－20thcentury’smostterribleepidemic．ForinadditiontoexplainingwhythissmallgroupofpeopleinfectedwithHIVhasnotbecomesick，thediscoveryofaviralstrainthatworkslikeavaccinewouldhavefar－reachingimplications．“Whattheseresultssuggest，”saysDr．BarneyGrahamofTennessee’sVanderbiltUniversity，“isthatHIVisvulnerableandthatitispossibletostimulateeffectiveimmunityagainstit．”

（4）ThestrainofHIVthatpoppedup？inSydneyintriguesscientistsbecauseitcontainsstrikingabnormalitiesinagenethatisbelievedtostimulateviralduplication．Infact，thevirusismissingsomuchofthisparticulargene—knownasnef，fornegativefactor—thatitishardtoimaginehowthegenecouldperformanyusefulfunction．Andsureenough，whiletheSydneyvirusretainstheabilitytoinfectTcells—whitebloodcellsthatarecriticaltothe

immunesystem’sabilitytowardoffinfection—itmakessofewcopiesofitselfthatthemostpowerfulmoleculartoolscanbarelydetectitspresence．SomeoftheinfectedAustralians，forexample，werefoundtocarryasfewasoneortwocopiesofthevirusforevery100000Tcells．PeoplewithAIDS，bycontrast，areburdenedwithviralloadsthousandsoftimeshigher．

（5）Attheveryleast，thenefgeneoffersanattractivetargetfordrugdevelopers．Ifitsactivitycanbeblocked，suggestsDeacon，researchersmightbeabletoholdtheprogressionofdiseaseatbay，eveninpeoplewhohavedevelopedfull－blownAIDS．TheneedforbetterAIDS－fightingdrugswasunderscoredlastweekbytheactionsofaU．S．FoodandDrugAdministrationadvisorypanel，whichrecommendedspeedyapprovaloftwonewAIDSdrugs，includingthefirstofanewclassofcompoundscalledprotease？inhibitors？．AlthoughFDAcommissionerDavidKesslerwasquicktopraisethenewdrugs，neithermedicationcanpreventorcureAIDSonceithastakenhold．

（6）Whatscientistsreallywantisavaccinethatcanpreventinfectionaltogether．Andthat’swhatmakestheSydneyvirussopromising—andsocontroversial．CouldHIVitself，strippedofnefandadjacentsectionsofgeneticmaterial，providethebasisforsuchavaccine，asDeaconandhiscolleaguescautiouslysuggest？OngoingworkonSIV，thesimian？immunodeficiencyvirusthatcausesanAIDS－likeillnessinmonkeys，indicatesthatthismightbelessfar－fetchedthanitsounds．RonaldDesrosiersattheNewEnglandRegionalPrimateRe－searchCenterhasdemonstratedthatwhenthenefgeneisremovedfromSIV，thevirusnolongerhasthepowertomakemonkeyssick．Moreover，monkeysinoculated？withtheneffreeSIVdevelopedmarkedresistancetothemorevirulentstrain．

（7）ButfewscientistsareenthusiasticabouttestingthepropositionbyinjectingHIV—howeverweakened—intomillionsofpeoplewhohaveneverbeeninfected．Afterall，theynote，HIVisaretrovirus？，aclassofinfectiousagentsknownfortheiralarmingabilitytointegratetheirowngenesintotheDNAofthecellstheyinfect．Thusonceittakeseffect，aretrovirusinfection—unlikethoseofvirusesthatcausemeasles，smallpoxandanynumberofothersdiseases—ispermanent．Whilesomeretrovirusesarebenign，otherscanstrikewithoutwarning．Someremainhiddenforyears，onlytotriggerdiseaselateinlifewhentheimmunesystemstartstodecrease．

（8）Thismakesvaccinedevelopmentextremelyrisky．AweakenedstrainofSIVthatprotectedadultmonkeys，forexample，lookedsafeuntil

researchersattheDanaFarberCancerInstituteinBostonshowedthatnewbornmonkeyswithimmatureimmunesystemsdidnotrespondashealthyadultsdo．Alltheyoungprimates，infact，developedtheverydiseasetheweakenedviruswassupposedtoprevent．Forthisandahostofotherreasons，mostAIDSresearchersarguethattheonlyprudentstrategyistoconcoct？ahybrid？vaccine，puttingthekeyfeaturesofadisabledAIDSvirusintosomethingmorebenignthanaretrovirus．Amongtheleadingcandidates：thevacciniavirusthatsuccessfullywipedoutsmallpox．

（9）Ahandfulofresearchers，however，arguethatthemoredangerousretroviralvaccineshouldnotbewrittenoffprematurely．Desrosiers，forone，believesthesituationinpartsofthedevelopingworld（wherethechanceofHIVinfectionmayreach40%amongsexuallyactiveadults）hasbecomesodesperatethataretroviralvaccinemaybeworththe______．AlivevaccinemadefromHIV，hemaintains，canbemadesaferbyremovingnotjustthenefgenebutseveralothersaswell．DesrosiershasfoundthathecancrippleHIVbychemicallydeletingfourofitsnineknowngenesandstillgetavirusthatreplicates，atleastinchimpanzees．

（10）Atpresent，concernsaboutsafetyaresooverwhelmingthateffortstodevelopaliveretroviralvaccineareunlikelytowinmuchsupport．Butthatcouldchangeasstudiesoflong－termsurvivors—thatsmall，charmedcircleofpeoplewhohavebeeninfectedwiththeAIDSvirusbuthaveremaineddisease-free—providenewinsightsintotheweaknessesoftheviralenemyandtheuntappedstrengthsofitshumantargets．“Theseindividuals，”observesDr．WarnerGreene，directoroftheGladstoneInstituteofVirologyandImmunologyinSanFrancisco，“arenaturalexperiments，andtheyholdagreatsecretthatwearestilltryingtodecipher？．”Indeed，itisentirelypossiblethattheeightAustralianswhohavecausedsuchastirwillbecitedbymedicaltextsasthefirstpeopleontheplanettobesuccessfully，ifaccidentally，vaccinatedagainsttheAIDSvirus—avirusthatuntilnowhasseemedallbutinvincible．

【譯文】

艾滋之謎揭曉

（1）大約在15年前，澳大利亞悉尼有一位人士好心向紅十字會捐血，別懂自個兒已感染HIV－1型——這是造成艾滋病的病毒。多年往后，公共衛(wèi)生官員發(fā)覺，有點同意他血液輸血的人，也受到病毒感染。這些人應該是難逃死亡的噩運。可是6年、10年、14年過去了，衛(wèi)生官員的焦慮變?yōu)轶@訝。盡管其中有兩個人因其他緣故死亡，可是同意遭污染血液輸血的這7個人當中，沒有一具人罹患艾滋病。更引人注目的是，那位捐血人——一具有性行為的同性戀者——仍然活得好好的。他的免疫系統(tǒng)十分強壯，就像從沒染上HIV一樣。這種意外的好運要怎么解釋？

（2）一批澳大利亞科學家終于解開了謎團。他們在上周的《科學》期刊發(fā)表報告指出：這位捐血人染上然后傳出去的病毒，基因結(jié)構(gòu)有缺陷，也許所以變成無害。澳大利亞麥法蘭？伯奈特醫(yī)學研究中心的分子生物學家迪肯嘖嘖稱奇：“捐血人與輸血人別僅15年來沒有發(fā)病，而且應該永久不可能發(fā)病?！钡峡洗竽懠僭O這種XXX的HIV甚至也許是天然的疫苗，能夠愛護帶原者別受更厲害的病XXX種侵襲，就好似18世紀擠牛奶的女工感染牛痘之后就能反抗天花一樣。

（3）假如那個預感成真，這么在圍堵20世紀末最可怕的傳染病的戰(zhàn)斗上，要立下一座里程碑。因為，發(fā)覺一種具有疫苗功能的病XXX種，別僅能解釋這一小群受到HIV感染的人何以別發(fā)病，還具有更深遠的涵義。田納西州范德堡大學的格雷姆博士講：“這些結(jié)果暗示HIV也有弱點，也表示有也許刺激免疫系統(tǒng)來有效地對抗它?！?/p>

（4）在悉尼發(fā)覺的這種HIV品種，引起科學家高度的頭趣，因為它有一具基因嚴峻異常。普通以為這是刺激病毒去復制自我的基因。這種病毒在那個叫做“否因”（代表否定因素）的基因中大部分殘缺別全，非常難想象那個基因能產(chǎn)生啥作用。果然，這種悉尼病毒盡管有能力感染T細胞（免疫系統(tǒng)對抗感染時最關(guān)鍵的白血球細胞），可是復制的能力極差，連最強大的分子工具也非常難偵測到它的存在。就拿受到感染的這些澳大利亞人來講，其中有點人體內(nèi)每10萬個T細胞才有一二個病毒。相反的，艾滋病患者則要承擔高幾千倍的病毒量。

（5）“否因”基因最低限度對制藥公司是非常大的誘惑。迪肯以為，如果可以阻斷這種基因的活動，研究人員就有也許阻撓病情的發(fā)展，就就是差不多全面發(fā)作的艾滋病病人也一樣實用。對更好的艾滋藥物需求十分殷切，這由美國食品藥物治理局（FDA）顧咨詢小組上周的一項行動能夠看出。那個小組建議盡快批準兩種艾滋新藥，包括一類全新的化合物，稱為蛋白酶抑制劑。FDA局長戴維？凱斯勒迅速稱贊這些新藥，可是這兩種藥都無法預防艾滋病，在感染艾滋病毒后也無法治愈。

（6）科學家真正想要的是能徹底預防感染的疫苗，因此悉尼病毒才被寄以厚望，也才會引起爭議。HIV病毒除去“否因”與鄰近的一些基因物質(zhì)后，是否真如迪肯和他的同僚審慎暗示的一樣，能夠作為艾滋病疫苗的基礎？那個構(gòu)想聽來非常勉強，然而目前對猿猴免疫別全病毒（SIV，造成猿猴罹患類似艾滋病的病毒）所做的研究顯示并非毫無依照。新英格蘭區(qū)靈長類研究中心的戴斯羅士差不多證明，從SIV中除去“否因”基因后，病毒就無法使猿猴發(fā)病。而且，猿猴接種過已去除“否因”的SIV后，會進展出明顯的反抗力，能夠反抗毒性強的SIV品種。

（7）然而沒有幾個科學家熱衷于檢驗那個構(gòu)想——在幾百萬個沒有感染過艾滋病的人身上注射HIV（別論削弱到啥程度）?？茖W家指出，怎么說HIV是逆轉(zhuǎn)錄酶病毒。這種傳染媒介原