HIV - A New Solution
- 1. HIV: a new solution? By Timothy Reed 11725855 The talk was givenby ProfessorDeirdre Hollingsworthandwastitled‘HIV infectivity:doesvariation matter’. As the title suggeststhe talkwasbasedaroundhow variationcanaffecta disease. Notonly disease variabilitybuthost variability aswell. Pathogenvariations suchasincubationperiod,viral loadand infectivity andhostvariationslikebehavioural differences,bothfrompersontopersonand between populations,andsusceptibility due toimmune responseandgenetics. Hollingsworth also talkedabouthowepidemicswere classifiedanddealtwith andintroduced ustoconcepts suchas superspreaders andtransmissiontrees. Superspreadersare people whoare highlyinfectious. Transmission mapsare diagrams whichshow the initial infectionandbranchingfromthere toall subsequently infections andsoon. The image below showsone of these mapsandyoucan easily see the superspreaders withinthe diagram. Hollingsworth alsoexplainedhowthe numberof transmissionsperinfectioniscalculated. Itiscalled the Basic ReproductionnumberorR0. It is foundbymultiplyingthe transmissionrate,whichis transmissionprobabilitybycontactrate,by the durationof the infection. If the figure isgreaterthan one the disease istechnicallyclassedasanepidemic. Thisfigure, although,ispopulationspecific. The publichealthimpactandtreatmentwasalsomentioned. Thiswas basically‘settingthe scene’forthe mainpartof the lecture whichwasthe researchshe and othershad done whichshowedthatHIV maybe evolvingto be have intermediate viral loads,viral
- 2. loadis the numberof viruseswithinanindividual. Hollingsworthproposedthathostswith intermediate loadslivedlongerandtherefore were infectiousforlongerperiodsof time in comparisontopeople withlowandhighviral loadswhowere either,notinfectiousyetlong-livedor highlyinfectiousyetshort-lived,respectively. Anotherkeypoint,andIthinkthe mostinteresting, was thatafter doinga summaryof previousstudies Hollingsworth showedthatthere wasa degree of heritabilityinSPVLorsetpointviral loads,thisbeing the amountof viruspresentafterthe initial spike inviral loadandis also the most commonlyusedidentifierof diseaseseverity. Thisis illustratedbelow inanimage take from,‘Virulence andPathogenesisof HIV-1Infection:An EvolutionaryPerspective’areviewHollingsworthwasinvolvedin. Both of these claimsgoagainstcurrent viewsheldonHIV. She herself saidthatafterproposingthat intermediate levelsof SPVLcouldbe beingselectedforandthattherefore itwasa heritable traitata recentseminarwasmetwitha queue of leadersinthe fieldof HIV tellingherhow she waswrong. Nowfor the part whichforme isthe most exciting,andwhichIthinkforany talk can be usedas a measure of itsquality,iswhetheritmakesyouthink aboutthe subjectmatter, questionitsfindings and wonderaboutfuture studiesorsolutions,whichIcertainlydid. Inthisinstance itisthe possibilityof Hollingsworthbeingright. If the data holdstrue,andHollingsworthisrightinsaying that there isa degree of heritabilityinHIV,thisopensupanentire areaof studyof HIV heritability and therefore anentirelynewperspective onHIV treatment. If the heritable viral factorscanbe narroweddowntospecificgenesorgene sets,new waysof treatingHIV couldbe foundthatcould provide more effectivedrugsthattargetthese importantviral factors,factorswhichare shownto be conservedacrossgenerationsof HIV. Alreadythereare studiestakingplace tothisaffectandthe nef factor or the nef-pathway hasbeenproposedasacandidate inaffectingviral load. Effective treatmentof HIV hasprovendifficult due tothe highvariance inhostHIV populations and the abilitytobecome drugresistantina matterof weeks, the implicationof findingconserved, targetable viral factorswhichare presentinall HIV strainsissomethingdefinitelyworthlookinginto as the benefitcouldbe enormous,inthe formof makingtargeteddrugsthatwill notelicitresistance inHIV and will affectall strains. This,as the title suggests,couldhopefullyprovideanew solution in the effective treatmentof HIV.