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inthe20yearssincethefirstcasesofaidsweredetected,scientistssaytheyhavelearnedmoreaboutthisviraldiseasethananyother.
yetpeterpiot,whodirectstheunitednationsaidsprogram,andstefanovellaofrome,presidentoftheinternationalaidssociety,andotherexpertssayreviewingunansweredquestionscouldproveusefulasameasureofprogressforaidsandotherdiseases.
amongtheimportantbroaderscientificquestionsthatremain：
whydoesaidspredisposeinfectedpersonstocertaintypesofcancerandinfections？
along-standingbeliefisthatcancercellsconstantlydevelopandareheldincheckbyahealthyimmunesystem.butaidshaschallengedthatbelief.peoplewithaidsaremuchmoreproocertaincancerslikenon-hodgkinslymphomasandkaposi’ssara,butnottobreast,colonandlung,themostmoncancersintheunitedstates.thispatternsuggeststhatanimpairedimmunesystem,atleastthetypethatoursinaids,doesnotallowmoncancerstodevelop.
whatroutedoeshivtakeafteritentersthebodytodestroytheimmunesystem？
whenhivistransmittedsexually,thevirusmustcrossatissuebarriertoenterthebody.howthathappensisstillunclear.thevirusmightinvadedirectlyorbecarriedbyaseriesofdifferentkindsofcells.
eventuallyhivtravelsthroughlymphvesselstolymphnodesandtherestofthelymphsystem.butwhatisnotknownishowthevirusproceedstodestroythebody’scd-4cellsthatareneededtobatinvadinginfectiousagents.
howdoeshivsubverttheimmunesys-tem？
althoughhivkillstheimmunecellssenttokillthevirus,thereiswidespreadvariationintherateatwhichhivinfectedpeoplebeeillwithaids.soscientistsask：cantheelementsoftheimmunesystemresponsibleforthatvariabilitybeidentified？ifso,cantheybeusedtostopprogressiontoaidsininfectedindividualsandpossiblypreventinfectioninthefirstplace？
whatisthemosteffectiveanti-hivtherapy？
intheory,earlytreatmentshouldofferthebestchanceofpreservingimmunefunction.butthenewdrugsdonotpletelyeliminatehivfromthebodysothemedicines,whichcanhavedangeroussideeffects,willhavetobetakenforalifetimeandperhapschangedtobatresistance.thenewpolicyisexpectedtoremendthattreatmentbedeferreduntiltherearesignstheimmunesystemisweakening.
isavainepossible？
thereislittlequestionthataneffectivevaineiscrucialtocontrollingtheepidemic.yetonlyonehasreachedthestageoffulltesting,andthereiswidecontroversyoverthedegreeofprotectionitwillprovide.hivstrainsthataretransmittedinvariousareasoftheworlddiffergeically.itisnotknownwhetheravainederivedfromoypeofhivwillconferprotectionagainstothertypes.
intheabsenceofavaine,howcanhivbestopped？
withoutmoreincisive,focusedbehavioralresearch,preventionmessagesalonewillnotstoptheglobalepidemic.