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3.1ImmuneSystemBacteria&Virusvideos..https://www.youtube.com/watch?v=kxM_9DL2GYwAmoebasisters4:39https://www.youtube.com/watch?v=8FqlTslU22s Amoeba sisters 6:48

InfectiousdiseasesJosephLister~1850• Recognizedthatmortalityaftersurgerywasveryhigh• Noticedthatcompoundfracturesthatrequiredsurgeryhadamuchhighermortalityratethansimplefracturesthatdidnotrequiresurgery

• Hypothesizedthatthesurgerycomponentwascausingthehighdeathrateandthatifsurgicaltoolswere“sterilized,”deathratesaftersurgerywoulddecline

• Foundthatusingantisepticstocleantoolswasverysuccessfulo InMunichthedeathratefrominfectionaftersurgerydroppedfrom80percenttoalmostzero

Waystotransmitdiseases:1. Directcontact:Shakinghandsorsharingdrinkingcontainersorbodilyfluidswithaninfectedperson.

2. Indirectcontact:Beingnearaninfectedpersonwhosneezeswithoutcoveringhisorhermouth.Somepathogenscantravelupto5metresandinfectpeoplewithinthatrange.

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3. Waterandfood:Eatingfoods,suchaseggsandsomemeats,thatareinfectedwithSalmonellabacteria.DrinkingwaterinfectedwithE.colibacteriacanalsoresultinseriousillness.

4. AnimalBites:Beingbittenbyananimalorinsectcarryingavirus–ForexamplerabiesorZika.

Immunesystem-Thebodysystemthatdefendsthebodyagainstinfectionanddisease-causingsubstancessuchasbacteria,virusesandcancercells.TheimmunesystemattacksandkillsinvaderssuchaspathogensandantigensPathogen–Anorganismorsubstancethatcancausedisease.Antigen–Anysubstancethatthebodycannotrecognize,usuallyanon-livingparticleAntibody–Aspecificparticlecreatedbytheimmunesystemtodestroyspecificdisease-causinginvaders.

AntibodyA

AntibodyB

Antigen

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WhiteBloodCells–Bloodcellscellsoftheimmunesystemthatareinvolvedinprotectingthebodyagainstbothinfectiousdiseaseandforeigninvaders.cellularcomponentofthebloodthatlackshemoglobin,hasanucleus,iscapableofmotility,anddefendsthebodyagainstinfectionanddiseasebyingestingforeignmaterialsandcellulardebris,bydestroyinginfectiousagentsandcancercells,orbyproducingantibodies.

SoHowDoOurImmuneSystemsRespondtoPathogens?FirstLineofDefense:• Theskinandinnerliningsofthebodysystemsarethefirstlineofdefense:o Skinactsasamechanicalbarrier–mostinfectiousagentscannotpenetratetheskin

o Sweat/Oilonskinareslightlyacidicwhichpreventspathogensfromgrowingontheskin

o Saliva,tearsandurineacttoexpelpathogens

Ascanningelectronmicroscope(SEM)imageofnormalcirculatinghumanblood.SeenareRBC,knobbyWBCandplatelets.

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o Enzymesinsalivaandtearsareantibacterial

o Gastricjuicesinthestomachisalsoacidicandhelpstodestroypathogens

o Coughing/Mucus/Cilia–preventspathogensfromenteringrespiratorysystem(orremovesonesthathaveentered)

SecondLineofDefense:• Onceapathogenhasenteredthebodyandpassedthefirstlineofdefense,thesecondlineofdefense,yourimmunesystem,kicksin.o Yourimmunesystemrecognizesforeigncellsorpathogensasinvaders.

o Differentpeoplewillresponddifferentlytothesamepathogendependingontheirimmunesystem(i.e.Elderlyvs.youngperson,healthypersonvs.personwithcancer)

ActiveImmuneSystem

Thekeyplayersintheactiveimmunesystemarethewhitebloodcells.Theyidentifyinvadingpathogensandeither

• engulfthemanddestroythem

• produceantibodieswhichkillthem,or

• produceantitoxinswhichneutralizetoxinsmadebytheinvaders

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Therearetwotypesofimmuneresponses:1. InnateImmuneResponseo Bornwiththistypeofimmuneresponse

o Quick

o Non-specific

• Yourbodywillreactthesameforanyinvader,virusor

bacteria

a) Flowoffluid,cellsanddissolvedsubstancesrushtothesiteofinfectionthroughtheblood

b) Feverdevelopsc) Swellingandrednessintheareawiththeinfection–CalledinflammationEg.Inflamedtonsils–infectedwithbacteriaorvirusbecomeredand

swollen.

d) IncreaseinWhiteBloodCellscalledPhagocytes–Fighttheinfectionby“swallowing”invadercells.

A white blood cell or phagocyte engulfing disease-causing bacteria

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2. AcquiredImmuneResponseo Developedoveryourlifetime(i.e.youacquireit)

o Slow–oftentakesaweektodevelop(yourbodyneedstimetofigureoutwhichresponsewillbestdefeattheinvader.

o Highlyspecifictoonetypeofpathogenorantigen.

• Antigenisanon-livingsubstanceyourbodydoesnotrecognize-virus,splinter,etc.

• Pathogenisalivingdiseasecausingorganismorsubstance–bacteria,etc.

Bodywillrespondinoneoftwoways: BCells1. BCellsrecognizeantigenspresentinthebody.

a. Eachtypeofbacteria,virusorotherforeignbodyhasmolecularmarkerswhichmakeitunique.

2. BCellsproduceantibodiestofightthespecificantigen.a. Antigen–amarkerthattriggerstheformationofWBCarmiesb. Antibody–moleculeswhichbindtoantigensandarerecognizedbyWBC.

Two different types of plant pathogens

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3. Antibodiesattachtoanddestroytheantigensandpathogenscarryingantigens.

4. BCellsnowrecognizetheantigenandwillproduceantibodiesthatcoverthepathogen.

5. Antibodiespreventpathogenfrominfectingthebody,ormarkittobedestroyedbyWBC.

6. BodyiscontinuallyproducingmoreBCellstofightotherantigensinthebody.

TCells1. Whenanantigenorpathogenhasinvadedacell,theWBC’srecognizethishashappenedandTCellsarecreated.

2. HelperTCellsactivateBCellstoproduceantibodies.a. Antibodiesnowrecognizethispathogenorantigenandcanhelpagainstfurtherinfection–IMMUNITY

3. KillerTCellscankillantigensorpathogensdirectlyandontheirown.

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AcquiredImmuneResponsesgiveyouactiveimmunity.Yourbodynowrememberswhichantibodiestousetokillcertainpathogensandantigensthathaveinvadedyourbodybefore.Ex.ChickenPox–Ifyouhavehadchickenpox,yourbodystoreschickenpoxantibodiesonBcells(memoryBCells–becausetheyrememberthepathogen).Bacteriaandimmunesystemvideos

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SummaryoftheImmuneResponse:

InnateImmuneSystem AcquiredImmuneSystem

Non-specific Pathogenandantigenspecific

Exposureleadstoimmediateresponse Lagtimebetweenexposureandresponse

Nomemory Exposureleadstoimmunologicalmemory

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BloodAntibodiesareproducedbytheimmunesystemtolabelinvadersfordestruction.Antibodiesareveryspecifictowhattheyattachthemselvesto.ThestructurethatanAntibodyattachestoiscalledanAntigen.Antigensarealsowhathelpstheimmunesystemdistinguishbetweenselfandnon-self.Sowhentheimmunesystemcomesincontactwithanunknownantigenthatisnon-self,itwilllabelthatantigenfordestructionwithanantibodyspecifictoonlythatantigen.Thisprocessisimportanttorememberwhentransfusingbloodproductstoapatient,becausebloodthatisnotcompatiblewiththeimmunesystemofthepatientcouldhavedisastrousresults.

Oneg Oneg

Opos Opos Oneg

Aneg Oneg Aneg

Apos Opos Oneg Apos Aneg

Bneg Oneg Bneg

Bpos Opos Oneg Bpos Bneg

ABneg Oneg Aneg Bneg ABneg

ABpos Opos Oneg Apos Aneg Bpos Bneg ABpos ABneg

Unknown Oneg Opos*

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VisualizingtheImmuneSystemReadthefollowingstatements.Thenuseagraphicorganizerinthespacebelowtorepresentyourunderstandingofhowthesestatementsfittogether.

• Theimmunesystemfightsoffinvaderssuchaspathogensandantigens.

• Theskinandtheliningoftheinternalbodysystemsstopmanypathogens.

• Whitebloodcellsdefendthebody.

• Phagocyteseatinvadercells.

• HelperTcellscontrolTandBcells.

• KillerTcellsdestroyinfectedcells.

• Bcellsmakeantibodies.

Your Immune System: Natural Born Killer – Crash Course Biology #32 - 15 minutes. • https://www.youtube.com/watch?v=CeVtPDjJBPU

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TheImmuneSystemOverviewIntroduction

Theimmunesystemprotectsusagainstbillionsofbacteria,viruses,andotherparasites.Mostofusneverreflectuponthefactthatwhilewehangoutwithourfriends,watchTV,orgotoschool,insideourbodies,ourimmunesystemisconstantlyonthealert,attackingatthefirstsignofaninvasionbyharmfulorganisms.

Theimmunesystemisverycomplex.It'smadeupofseveraltypesofcellsandproteinsthathavedifferentjobstodoinfightingforeigninvaders.Inthissection,we'lltakealookatthepartsoftheimmunesysteminsomedetail.

Wearesurroundedbybillionsofbacteriaandviruses.Tomanyofthem,ahumanbeingislikeawalkingsmorgasbord,offeringnearlylimitlessresourcesthattheycanuseforenergyandreproduction.Luckilyforus,gettingintothehumanbodyisnotaneasytask!Fromthepointofviewofthesetinyorganisms,ahumanisabitlikeafortress.Theskinisthickandveryhardtopenetrate.Inaddition,theskinalsoproducesavarietyofsubstancesthatareharmfultoinvaders.Openingssuchastheeyes,nose,andmouthareprotectedbyfluidsorstickymucusthatcaptureharmfulattackers.

Therespiratorytractalsohasmechanicaldefensesintheformofcilia,tinyhairsthatremoveparticles.Intrudersthatgetasfarasthestomachareupagainstaseaofstomachacidthatkillsmostofthem.

Butinspiteofourfantasticdefenses,hostileinvadersstillmanagetogetthrough.Someenteralongwithourfood,whileothersmaysneakinviathenose.And,asweallknow,manythingscanbreakthroughourskin.Ineverydaylifeweoftenreceivecutsorscrapes,andeverytimethishappenswefacetheriskofafull-scaleinvasionfrombacteriaorviruses.Whatisthemagic,then,thatkeepsushealthymostofthetime?

Whenwereceiveacut,andwheninvadersenterthebody,cellsaredestroyed.Thedyingcellstriggeranautomaticresponsecalledinflammation,whichincludesdilatedbloodvesselsandincreasedbloodflow.Aninflammationisthebody'sequivalenttoaburglaralarm.Onceitgoesoff,itdrawsdefensivecellstothedamagedareaingreatnumbers.Increasedbloodflowhelpsdefensivecellsreachtheplacewherethey'reneeded.Italsoaccountsfortherednessandswellingthatoccur.

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ImmuneCells:TheDefense

Thedefensivecellsaremorecommonlyknownasimmunecells.Theyarepartofahighlyeffectivedefenseforcecalledtheimmunesystem.Thecellsoftheimmunesystemworktogetherwithdifferentproteinstoseekoutanddestroyanythingforeignordangerousthatentersourbody.Ittakessometimefortheimmunecellstobeactivated-butoncethey'reoperatingatfullstrength,thereareveryfewhostileorganismsthatstandachance.

Immunecellsarewhitebloodcellsproducedinhugequantitiesinthebonemarrow.Thereareawidevarietyofimmunecells,eachwithitsownstrengthsandweaknesses.Someseekoutanddevourinvadingorganisms,whileothersdestroyinfectedormutatedbodycells.Yetanothertypehastheabilitytoreleasespecialproteinscalledantibodiesthatmarkintrudersfordestructionbyothercells.

Butthereallycoolthingabouttheimmunesystemisthatithastheabilityto"remember"enemiesthatithasfoughtinthepast.Iftheimmunesystemdetectsa"registered"invader,itwillstrikemuchmorequicklyandmorefiercelyagainstit.Asaresult,aninvaderthattriestoattackthebodyasecondtimewillmostlikelybewipedoutbeforethereareanysymptomsofdisease.Whenthishappens,wesaythatthebodyhasbecomeimmune.

BacteriaandViruses:OurMainEnemies

Bacteriaandvirusesaretheorganismsmostoftenresponsibleforattackingourbodies.Mostbacteriaarefreeliving,whileothersliveinoronotherorganisms,includinghumans.Unfortunately,manybacteriathathavehumanhostsproducetoxins(poisons)thatdamagethebody.Notallbacteriaareharmful,though.Someareneutralandmanyareevendesirableastheyfulfillimportantfunctionsinthebody.

Bacteriaarecompleteorganismsthatreproducebycelldivision.Viruses,ontheotherhand,cannotreproduceontheirown.Theyneedahostcell.Theyhijackbodycellsofhumansorotherspecies,andtrickthemintoproducingnewvirusesthatcantheninvadeothercells.Frequently,thehostcellisdestroyedduringtheprocess.

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PathogensandAntigens

Indailylifewemightspeakofviruses,bacteria,andtoxins.However,whenreadingabouttheimmunesystemyouwilloftencomeacrossthewordsantigenandpathogen.Anantigenisaforeignsubstancethattriggersareactionfromtheimmunesystem.Antigensareoftenfoundonthesurfacesofbacteriaandviruses.Apathogenisamicroscopicorganismthatcausessickness.Hostilebacteriaandvirusesareexamplesofpathogens.

TheImmuneResponse

TheComplementSystem

Thefirstpartoftheimmunesystemthatmeetsinvaderssuchasbacteriaisagroupofproteinscalledthecomplementsystem.Theseproteinsflowfreelyinthebloodandcanquicklyreachthesiteofaninvasionwheretheycanreactdirectlywithantigens-moleculesthatthebodyrecognizesasforeignsubstances.Whenactivated,thecomplementproteinscan

o triggerinflammation:o attracteatercellssuchasmacrophagestotheareao coatintruderssothateatercellsaremorelikelytodevourthemo killintruders

PhagocytesThisisagroupofimmunecellsspecializedinfindingand"eating"bacteria,viruses,anddeadorinjuredbodycells.Therearethreemaintypes,thegranulocyte,themacrophage,andthedendriticcell.

Thegranulocytesoftentakethefirststandduringaninfection.Theyattackanyinvadersinlargenumbers,and"eat"untiltheydie.Thepusinaninfectedwoundconsistschieflyofdeadgranulocytes.Asmallpartofthegranulocytecommunityisspecializedinattackinglargerparasitessuchasworms.

Themacrophages("bigeaters")areslowertorespondtoinvadersthanthegranulocytes,buttheyarelarger,livelonger,andhavefargreatercapacities.Macrophagesalsoplayakeypartinalertingtherestoftheimmunesystemofinvaders.Macrophagesstartoutaswhitebloodcellscalledmonocytes.Monocytesthatleavethebloodstreamturnintomacrophages.

Thedendriticcellsare"eater"cellsanddevourintruders,likethegranulocytes andthemacrophages.Andlikethemacrophages,thedendriticcellshelpwiththe activationoftherestoftheimmunesystem.Theyarealsocapableoffilteringbodyfluidstoclear themofforeignorganismsandparticles.

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Lymphocytes-TcellsandBcells

Whitebloodcellscalledlymphocytesoriginateinthebonemarrowbutmigratetopartsofthelymphaticsystemsuchasthelymphnodes,spleen,andthymus.Therearetwomaintypesoflymphaticcells,TcellsandBcells.Thelymphaticsystemalsoinvolvesatransportationsystem-lymphvessels-fortransportationandstorageoflymphocytecellswithinthebody.Thelymphaticsystemfeedscellsintothebodyandfiltersoutdeadcellsandinvadingorganismssuchasbacteria.

Onthesurfaceofeachlymphaticcellarereceptorsthatenablethemtorecognizeforeignsubstances.Thesereceptorsareveryspecialized-eachcanmatchonlyonespecificantigen.

Tounderstandthereceptors,thinkofahandthatcanonlygrabonespecificitem.Imaginethatyourhandscouldonlypickupapples.Youwouldbeatrueapple-pickingchampion-butyouwouldn'tbeabletopickupanythingelse.

Inyourbody,eachsinglereceptorequalsahandinsearchofits"apple."Thelymphocytecellstravelthroughyourbodyuntiltheyfindanantigenoftherightsizeandshapetomatchtheirspecificreceptors.Itmightseemlimitingthatthereceptorsofeachlymphocytecellcanonlymatchonespecifictypeofantigen,butthebodymakesupforthisbyproducingsomanydifferentlymphocytecellsthattheimmunesystemcanrecognizenearlyallinvaders.

Tcells

Tcellscomeintwodifferenttypes,helpercellsandkillercells.TheyarenamedTcellsafterthethymus,anorgansituatedunderthebreastbone.Tcellsareproducedinthebonemarrowandlatermovetothethymuswheretheymature.

HelperTcellsarethemajordrivingforceandthemainregulatorsoftheimmunedefense.TheirprimarytaskistoactivateBcellsandkillerTcells.However,thehelperTcellsthemselvesmustbeactivated.Thishappenswhenamacrophageordendriticcell,whichhaseatenaninvader,travelstothenearestlymphnodetopresentinformationaboutthecapturedpathogen.Thephagocytedisplaysanantigenfragmentfromtheinvaderonitsownsurface,aprocesscalledantigenpresentation.WhenthereceptorofahelperTcellrecognizestheantigen,theTcellisactivated.Onceactivated,helperTcellsstarttodivideandtoproduceproteinsthatactivateBandTcellsaswellasotherimmunecells.

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ThekillerTcellisspecializedinattacking

cellsofthebodyinfectedbyvirusesandsometimesalsobybacteria.Itcanalsoattackcancercells.ThekillerTcellhasreceptorsthatareusedtosearcheachcellthatitmeets.Ifacellisinfected,itisswiftlykilled.Infectedcellsarerecognizedbecausetinytracesoftheintruder,antigen,canbefoundontheirsurface.

BCells

TheBlymphocytecellsearchesforantigenmatchingitsreceptors.Ifitfindssuchantigenitconnectstoit,andinsidetheBcellatriggeringsignalissetoff.TheBcellnowneedsproteinsproducedbyhelperTcellstobecomefullyactivated.Whenthishappens,theBcellstartstodividetoproduceclonesofitself.Duringthisprocess,twonewcelltypesarecreated,plasmacellsandBmemorycells.

Theplasmacellisspecializedinproducingaspecificprotein,calledanantibody,thatwillrespondtothesameantigenthatmatchedtheBcellreceptor.Antibodiesarereleasedfromtheplasmacellsothattheycanseekoutintrudersandhelpdestroythem.Plasmacellsproduceantibodiesatanamazingrateandcanreleasetensofthousandsofantibodiespersecond.

WhentheY-shapedantibodyfindsamatchingantigen,itattachestoit.Theattachedantibodiesserveasanappetizingcoatingforeatercellssuchasthemacrophage.Antibodiesalsoneutralizetoxinsandincapacitateviruses,preventingthemfrominfectingnewcells.EachbranchoftheY-shapedantibodycanbindtoadifferentantigen,sowhileonebranchbindstoanantigenononecell,theotherbranchcouldbindtoanothercell-inthiswaypathogensaregatheredintolargergroupsthatareeasierforphagocytecellstodevour.Bacteriaandotherpathogenscoveredwithantibodiesarealsomorelikelytobeattackedbytheproteinsfromthecomplementsystem.

TheMemoryCellsarethesecondcelltypeproducedbythedivisionofBcells.Thesecellshaveaprolongedlifespanandcanthereby"remember"specificintruders.Tcellscanalsoproducememorycellswithanevenlongerlife

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spanthanBmemorycells.Thesecondtimeanintrudertriestoinvadethebody,BandTmemorycellshelptheimmunesystemtoactivatemuchfaster.Theinvadersarewipedoutbeforetheinfectedhumanfeelsanysymptoms.Thebodyhasachievedimmunityagainsttheinvader.

Conclusion

Althoughratherlongandcomplex,ourpresentationisjustaglimpseoftheimmunesystemandtheintricatewaysinwhichitsvariouspartsinteract.Immunityisafascinatingsubjectthatstillconcealsmanysecrets.Whentheimmunesystemisfullyunderstood,itwillmostlikelyholdthekeytoriddinghumankindofmanyofitsmostfeareddiseases.

http://ed.ted.com/lessons/how-pandemics-spread#watchhttps://www.youtube.com/watch?v=WimZ3oRkbFQ

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1. About150yearsagoascientisthadtheideatosterilizemedicalequipmentbeforesurgery.Theidea

wasthatinvisibleorganisms(germs)wereresponsibleforcausinginfections.Thenameofthisscientistwas

A. TheodoreSchwannB. EdwardJennerC. JosephListerD. MaryMontagu

2. Whichofthefollowingwouldnotbeconsidereda"firstlineofdefense"ofyourbodyagainst

pathogensA. Stomachaciddestroysaforeigninvaderthatenteredwithsomefoodyouate.B. MucusinyournasalcavitycatchesagermandstopsitfromenteringyourlungsC. Yourskinstopsapathogenfromenteringyourbody.D. Aphagocyteconsumesaforeigninvaderinthebloodstream

3. Theinnateimmuneresponse

A. InvolvestheproductionofantibodiesB. Isanon-specificresponsetoaninvadingpathogenC. OccursinthestomachwhereaciddestroysgermsD. CausesthecreationofhelperTcells

4. Partofyourimmunesystem’sresponsetoaninvadingpathogenisBcellsproducing

A. AntibodiesB. PhagocytesC. TcellsD. Antigens

3.1ImmuneSystemQuiz Name:____________________

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Thefollowingdiagramrepresentsthefourstepsintheacquiredimmuneresponse.

5.WhichofthefollowingtermsisthecorrectlabelforstepAinthediagram?

E. DisposalF. ImmunityG. MobilizationH. Recognition

6.WhichofthefollowingtermsisthecorrectlabelforstepBinthediagram?

A. DisposalB. ImmunityC. MobilizationD. Recognition

7.WhatisoccurringduringstepCoftheimmuneresponseasindicatedinthediagram?

A. AntibodiesaredestroyingpathogensB. PathogensaredestroyingantigensC. AntigensaredestroyinggermsD. Pathogensaredestroyingantibodies

8. ThelaststepoftheimmuneasindicatedbylabelDinthediagram,createsaspecialtypeofBcell

knownasa

A. AntibodyBcellB. KillerBcellC. AntigenBcellD. MemoryBcell

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Answers

1. C2. D3. B4. A5. D6. B7. A8. D

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3.2FactorsAffectingtheImmuneSystemHowVaccinesPreventDiseases–CDC(CentresforDiseaseControlandPrevention)

Thediseasesthatvaccinespreventcanbedangerous,orevendeadly.Vaccinesreducetheriskofinfectionbyworkingwiththebody’snaturaldefensestohelpitsafelydevelopimmunitytodisease.

Whengerms,suchasbacteriaorviruses,invadethebody,theyattackandmultiply.Thisinvasioniscalledaninfection,andtheinfectioniswhatcausesillness.Theimmunesystemthenhastofighttheinfection.Onceitfightsofftheinfection,thebodyisleftwithasupplyofcellsthathelprecognizeandfightthatdiseaseinthefuture.

Vaccineshelpdevelopimmunitybyimitatinganinfection,butthis“imitation”infectiondoesnotcauseillness.Itdoes,however,causetheimmunesystemtodevelopthesameresponseasitdoestoarealinfectionsothebodycanrecognizeandfightthevaccine-preventablediseaseinthefuture.Sometimes,aftergettingavaccine,theimitationinfectioncancauseminorsymptoms,suchasfever.Suchminorsymptomsarenormalandshouldbeexpectedasthebodybuildsimmunity.

https://www.canada.ca/content/dam/phac-aspc/documents/services/publications/healthy-living/parent-guide-vaccination/pgi-gpv-eng.pdf

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TheHistoryofVaccinesActivityUSINGHISTORYOFVACCINEINTHECLASSROOMhttps://www.historyofvaccines.org/content/educatorsPartB:Two50-minuteclassperiodsLearningObjectives-AftercompletingPartBofthislesson,studentswillbeableto:

•explainhowvaccineswork

•describedifferentvaccinesandthediseasestheyprevent

•describeseveralimmunizationpioneersandthecontributionstheymade

•describehowthescientificmethodisemployedintheinvestigationofadiseaseoutbreak

•listfactorsthatcontributetoasociety’sabilitytocreateandusevaccines

•explainhowpublichealthandvaccinationstrategiescanlimitthespreadofadisease

•describesomeofthelimitationsofpublichealthmeasuresincontrollingdiseasespread

TeacherPreparation:

•PlantohavethestudentsusetheInternetduringclass.•Makecopiesoftherecordingsheets,onepergroup.Thereproduciblesarefoundattheendofthisdocument.

OpeningActivityIntroduceDiseaseandVaccinationTime:5minutes1. Introducethetopicofinfectiousdiseaseandvaccinationbyleadingaclassdiscussion.Askthe

studentstodescribeexperiencestheyhavehadwithinfectiousdiseaseandvaccination.

2. Askstudents,Whydowevaccinate?Whatdoyouthinkwouldhappeniftherewereaproblemwithvaccinesupply,andwecouldnolongervaccinateformeasles?Studentsmaynotrealizethatmeaslesisahighlyinfectious(easilyspreaddisease)andthatwhilemostmeaslescasesaremild,inthepre-vaccineera,about1in1,000childrenwhocaughtmeaslesdiedfromit.

3. Invitestudentstotellyouwhattheyknowaboutthehistoryofvaccines.Askthem,whatwasthe

firstvaccinefor?Whodevelopedit?SomestudentsmayknowthatthefirstvaccinewasdevelopedbyEnglishphysicianEdwardJenner,whousedmattertakenfromcowpoxsorestoprotectpeoplefromsmallpox.TellstudentsthatJennerdevelopedhisvaccinebeforepeopleknewthatinfectiousdiseaseswerespreadbymicrobes.

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PartB:UsingtheHistoryofVaccinesWebsitehttps://www.historyofvaccines.org/Time:75-90minutes1. Tellthestudentsthattheywillbeexploringwebresourcesrelatedtothehistoryofvaccine

development.Telleachgroupofstudentsthattheyareresponsibleforgatheringinformationabouttwodiseases/vaccinesandtwopioneersofimmunization.(Optionsfordiseasesareyellowfever,smallpox,measles,polio,anddiphtheria.OptionsforpioneersareMauriceHilleman,LouisPasteur,andEdwardJenner.)

Theyarealsoresponsibleforcompletingoneofthefollowinglearningactivities:• ScientificMethodactivity• HowVaccinesWorkactivity

2. Giveeachgrouptheappropriaterecordingsheets.Letthemknowthattheyareresponsiblefor

gatheringinformationandreportingtotheclasswhattheyhavelearned.

3. HavestudentsaccessthespecificsectionoftheHistoryofVaccinestowhichtheyhavebeenassigned.(ActivitiescanbefoundbyclickingACTIVITIESonthemainnavigationbar.)

Circulateamongthegroupsastheywork,ensuringthattheystayontaskandarefindingtheresourcestheyneed.GivestudentsabouthalftheallottedtimetoexploretheresourcesassignedinStep1.4. Next,tellstudentsthattheyhavegatheredenoughinformationaboutvaccinesandinfectious

diseasetocompletethegameAgeofDisease(again,foundbyclickingACTIVITIESonthemainnavigationbar.).

Ifclasstimeisrunningshort,youmayassignthegameasahomeworkassignment.5. Tellstudentsthatthegameisdesignedtosimulateadiseaseepidemic,includingthespreadof

disease,howvaccinationworkstocontroldiseasespread,andhowpublichealthmeasurescanaffecttheoutcomeofanepidemic.

6. Oncethestudentshavecompletedthegame,haveaclassdiscussionabouttheresultsofthesimulation

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Top20QuestionsaboutVaccination

1. Howdovaccineswork?Dotheyworkagainstvirusesandbacteria?

Vaccinesworktoprimeyourimmunesystemagainstfuture“attacks”byaparticulardisease.Therearevaccinesagainstbothviralandbacterialpathogens,ordisease-causingagents.

Whenapathogenentersyourbody,yourimmunesystemgeneratesantibodiestotrytofightitoff.Dependingonthestrengthofyourimmuneresponseandhoweffectivelytheantibodiesfightoffthepathogen,youmayormaynotgetsick.

Ifyoudofallill,however,someoftheantibodiesthatarecreatedwillremaininyourbodyplayingwatchdogafteryou’renolongersick.Ifyou’reexposedtothesamepathogeninthefuture,theantibodieswill”recognize”itandfightitoff.

Vaccinesworkbecauseofthisfunctionoftheimmunesystem.They’remadefromakilled,weakened,orpartialversionofapathogen.Whenyougetavaccine,whateverversionofthepathogenitcontainsisn’tstrongorplentifulenoughtomakeyousick,butit’senoughforyourimmunesystemtogenerateantibodiesagainstit.Asaresult,yougainfutureimmunityagainstthediseasewithouthavinggottensick:ifyou’reexposedtothepathogenagain,yourimmunesystemwillrecognizeitandbeabletofightitoff.

Somevaccinesagainstbacteriaaremadewithaformofthebacteriaitself.Inothercases,theymaybemadewithamodifiedformofatoxingeneratedbythebacteria.Tetanus,forexample,isnotdirectlycausedbytheClostridiumtetanibacteria.Instead,itssymptomsareprimarilycausedbytetanospasmin,atoxingeneratedbythatbacterium.Somebacterialvaccinesarethereforemadewithaweakenedorinactivatedversionofthetoxinthatactuallyproducessymptomsofillness.Thisweakenedorinactivatedtoxiniscalledatoxoid.Atetanusimmunization,forexample,ismadewithtetanospasmintoxoid.

2. Whyaren’tallvaccines100%effective?

Vaccinesaredesignedtogenerateanimmuneresponsethatwillprotectthevaccinatedindividualduringfutureexposurestothedisease.Individualimmunesystems,however,aredifferentenoughthatinsomecases,aperson’simmunesystemwillnotgenerateanadequateresponse.Asaresult,heorshewillnotbeeffectivelyprotectedafterimmunization.

Thatsaid,theeffectivenessofmostvaccinesishigh.AfterreceivingtheseconddoseoftheMMRvaccine(measles,mumpsandrubella)orthestandalonemeaslesvaccine,99.7%ofvaccinatedindividualsareimmunetomeasles.Theinactivatedpoliovaccineoffers99%effectivenessafterthreedoses.Thevaricella(chickenpox)vaccineisbetween85%and90%effectiveinpreventingallvaricellainfections,but100%effectiveinpreventingmoderateandseverechickenpox.

3. Whyaretheresomanyvaccines?

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Currently,theU.S.childhoodvaccinationscheduleforchildrenbetweenbirthandsixyearsofagerecommendsimmunizationsfor14differentdiseases.Someparentsworrythatthisnumberseemshigh,particularlysincesomeofthediseasesbeingvaccinatedagainstarenowextremelyrareintheUnitedStates.

Eachdiseaseforwhichvaccinationsarerecommended,however,cancausesseriousillnessordeathinunvaccinatedpopulations,andmightquicklybegintoappearagainifvaccinationratesdropped.TheUnitedStateshasseenmumpsoutbreaksinrecentyearssincevaccinationrateshavedropped,withseverecomplicationsandhospitalizationsrequiredforsomepatients.AndbeforetheintroductionoftheHib(HaemophilusInfluenzaeTypeb)vaccine,Hibmeningitisaffectedmorethan12,000Americanchildrenannually,killing600andleavingmanyotherswithseizures,deafness,anddevelopmentaldisabilities.Afterintroductionofthevaccine,thenumberofdeathsfromHibdroppedtofewerthan10peryear.

Eachvaccineontheschedulecontinuestoberecommendedbecauseoftherisksposedbywildinfection.

4. Isnaturalimmunitybetterthanvaccine-acquiredimmunity?

Insomecases,naturalimmunityislonger-lastingthantheimmunitygainedfromvaccination.Therisksofnaturalinfection,however,outweightherisksofimmunizationforeveryrecommendedvaccine.Forexample,wildmeaslesinfectioncausesencephalitis(inflammationofthebrain)foronein1,000infectedindividuals.Overall,measlesinfectionkillstwoofevery1,000infectedindividuals.Incontrast,thecombinationMMR(measles,mumpsandrubella)vaccineresultsinasevereallergicreactiononlyonceineverymillionvaccinatedindividuals,whilepreventingmeaslesinfection.Thebenefitsofvaccine-acquiredimmunityextraordinarilyoutweightheseriousrisksofnaturalinfection.(Formoreonthistopic,seeourUnderstandingRisksactivity.)

Additionally,theHib(Haemophilusinfluenzaetypeb)andtetanusvaccinesactuallyprovidemoreeffectiveimmunitythannaturalinfection.

5. Whydosomevaccinesrequireboosters?

It’snotcompletelyunderstoodwhythelengthofacquiredimmunityvarieswithdifferentvaccines.Someofferlifelongimmunitywithonlyonedose,whileothersrequireboostersinordertomaintainimmunity.Recentresearchhassuggestedthatthepersistenceofimmunityagainstaparticulardiseasemaydependonthespeedwithwhichthatdiseasetypicallyprogressesthroughthebody.Ifadiseaseprogressesveryrapidly,theimmunesystem’smemoryresponse(thatis,the“watchdogantibodies”generatedafterapreviousinfectionorvaccination)maynotbeabletorespondquicklyenoughtopreventinfection—unlessthey’vebeen“reminded”aboutthediseasefairlyrecentlyandarealreadywatchingforit.Boostersserveasa“reminder”toyourimmunesystem.

Researchiscontinuingonthepersistenceofimmunitygeneratedbyvaccines.

6. Mychildwasinvitedtoachickenpoxparty.Woulditbebetterformychildtogetthechickenpoxthisway?Whydowevaccinateagainstamilddiseaselikechickenpox?

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Theideaof“poxparties”isgenerallytiedtotheperceptionofchickenpoxasaharmlessillness.Beforethevaricellavaccinebecameavailable,however,chickenpoxinfectionsrequired10,000hospitalizationsandcausedmorethan100deathseachyearintheUnitedStates.Exposingachildtowildchickenpoxputshimatriskforaseverecaseofthedisease.

Evenuncomplicatedcasesofchickenpoxcausechildrentomissaweekormoreofschool,withacaregivermissingworktocareforthesickchild.[1]Naturalinfectionalsomeansariskofinfectingothers:whilesuccessfulvaccinationprotectsachildagainstchickenpoxwithoutthisrisk,childrenwhoareinfectedwithchickenpoxnaturallyarecontagious.Theycanspreadthediseasetootherpeople—notjustotherchildren,butalsoadults,whohaveahigherriskofcomplicationsfromthedisease.

Meanwhile,vaccinationforchickenpoxtypicallypreventsfutureinfectionwiththedisease.Intherarecaseswhereindividualsdonotdevelopadequateprotectionfromvaccinationtopreventfutureinfection,chickenpoxinfectionistypicallymild,resultsinfewersymptoms,andendsmorequicklythannaturalinfection.(Peoplewiththismildformarecontagious,however,andshouldtakecarenottoexposeotherstothevirus.)

7. Canyougetadiseasefromthevaccinethat’ssupposedtopreventit?Andwhydosomevaccineshavelivepathogensbutothershavekilledpathogens?

Vaccinesthataremadewithkilledversionsofpathogens—orwithonlyapartofthepathogen—arenotabletocauseillness.Whenapersonreceivesthesevaccines,itisimpossibleforhimorhertobecomeillwiththedisease.

Live,attenuated(orweakened)vaccinesaretheoreticallycapableofcausingillness:becausetheycanstillreplicate(thoughnotwell),mutationispossible,whichcanresultinavirulentformofthepathogen.However,theyaredesignedwiththisinmind,andattenuatedtominimizethispossibility.Reversiontovirulentformisaproblemwithsomeformsoftheoralpoliovaccine(OPV),whichiswhyonlytheinactivatedform(IPV)isnowusedintheUnitedStates.

Itisimportanttonotethatattenuatedvaccinescancauseseriousproblemsforindividualswithweakenedimmunesystems,suchascancerpatients.Theseindividualsmayreceiveakilledformofthevaccineifoneisavailable.Ifnot,theirdoctorsmayrecommendagainstvaccination.Insuchcases,individualsrelyonherdimmunityforprotection.

Astowhysomevaccinescontainlivepathogensandotherscontainkilledpathogens,thereasonsvarybyillness.However,generallyspeaking,live,attenuatedvaccinesgeneratelonger-lastingimmunitythankilledvaccines.Thus,killedvaccinesaremorelikelytorequireboosterstomaintainimmunity.Killedvaccines,however,alsotendtobemorestableforstoragepurposes,andcan’tcauseillness.Themedicalcommunitymustweighthesetrade-offsindecidingwhichapproachtouseagainstaparticulardisease.

8. Canbabies’immunesystemshandlesomanyvaccines?

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Yes.Studiesdemonstratethatinfants’immunesystemscanhandlereceivingmanyvaccinesatonce—morethanthenumbercurrentlyrecommended.Theimmunizationscheduleisbasedoninfants’abilitytogenerateimmuneresponses,aswellaswhentheyareatriskofcertainillnesses.Forexample,theimmunitypassedfrommothertochildatbirthisonlytemporary,andtypicallydoesnotincludeimmunityagainstpolio,hepatitisB,Haemophilusinfluenzaetypeb,andotherdiseasesthatcanbepreventedbyvaccination.

9. Whyisthereanewfluvaccineeveryyear?

Unlikemostvaccines,whichcontainthemostcommonstrainsofagivenpathogen(ifmorethanoneexists)andarerarelychanged,theseasonalfluvaccinechangesfrequently,thoughoneormoreoftheflustrainsinthevaccinemayberetainedfromoneyeartothenext.Thisisbecausethestrainsofinfluenzavirusesthatcirculateareconstantlychanging.Eachyear,researcherschoosevirusesforthevaccinebasedonwhichonesarelikelytobecirculatingoverthecourseofthecomingfluseason,thusprovidingprotectionagainstthemostprevalentstrains.Sowhenyougetaseasonalfluvaccine,you’reusuallynotgettinganother“dose”ofthesamefluvaccineyouweregivenbefore.Instead,you’reusuallygettingprotectionagainstawholenewbatchoffluviruses.

10. Whatisherdimmunity?Isitreal?Doesitwork?

Herdimmunity,alsoknownascommunityimmunity,referstotheprotectionofferedtoeveryoneinacommunitybyhighvaccinationrates.Withenoughpeopleimmunizedagainstagivendisease,it’sdifficultforthediseasetogainafootholdinthecommunity.Thisofferssomeprotectiontothosewhoareunabletoreceivevaccinations—includingnewbornsandindividualswithchronicillnesses—byreducingthelikelihoodofanoutbreakthatcouldexposethemtothedisease.

11. Whyisallergytoeggsacontraindicationtogettingsomevaccines?

Somevaccines,includingthemajorityofvaccinesagainstinfluenza,areculturedinchickeneggs.Duringtheprocessofcreatingthevaccine,themajorityoftheeggproteinisremoved,butthereissomeconcernthatthesevaccinesmightgenerateanallergicreactioninindividualswithaneggallergy.

Arecentreportfoundthatthemajorityofchildrenwitheggallergieswhoweregivenaflushothadnoadversereactions;about5%ofchildreninthestudiedgroupdevelopedrelativelyminorreactionssuchashives,themajorityofwhichresolvedwithouttreatment.[2]Additionalresearchisunderwaytostudythisissuefurther.

Inmostcases,onlypeoplewithasevere(life-threatening)allergytoeggsarerecommendedagainstreceivingegg-basedvaccines.Yourdoctorcanprovidespecificinformation.

12. Dovaccinescauseautism?

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No.Vaccinesdonotcauseautism.Thispossibilitywaspublicizedaftera1998paperbyaBritishphysicianwhoclaimedtohavefoundevidencethattheMMR(measles,mumpsandrubella)vaccinewaslinkedtoautism.Thepotentiallinkhasbeenthoroughlyexplored;studyafterstudyhasfoundnosuchlink,andtheoriginal1998studyhasbeenformallywithdrawnbyTheLancet,whichhadoriginallypublishedit.Studieswerealsodoneregardingthepossibilityofalinkbetweenthepreservativethimerosal,whichisusedinsomevaccines,andautism;again,nosuchlinkwasfound.

It’slikelythatthismisconceptionpersistsbecauseofthecoincidenceoftimingbetweenearlychildhoodvaccinationsandthefirstappearanceofsymptomsofautism.

13. Peoplesaythatvaccinesarelinkedtolong-termhealthproblemssuchasmultiplesclerosis,diabetes,andautism.Isthattrue?

Allvaccineshavepossiblesideeffects.Most,however,aremildandtemporary.Adverseeffectsfromvaccinesaremonitoredthoroughlyviamultiplereportingsystems,andthereisnoevidencefromthesesystemstosupporttheseclaims.

14. Thevaccineinformationsheetformychild’srecentvaccinationlistedlotsofpotentialsideeffects.Whyisvaccinationrecommendedifitcancauseallofthesesideeffects?

Everyvaccinehaspotentialsideeffects.Typicallytheyareverymild:sorenessattheinjectionsite(foravaccinedeliveredviaashot),headaches,andlow-gradefeversareexamplesofcommonvaccinesideeffects.Serioussideeffectsarepossible,however,includingsevereallergicreactions.However,theoccurrenceofthesesideeffectsisextremelyrare.(Yourdoctorcanexplaintherisksforindividualvaccinesindetail;moreinformationisalsoavailablefromtheCentersforDiseaseControlandPrevention.)

Whenconsideringpossiblesideeffectsfromvaccination,it’simportanttodosoincontext.Whilesomepossiblesideeffectsareserious,theyareextremelyrare.It’simportanttorememberisthatchoosingnottovaccinatealsohasseriousrisks.Vaccinesprotectagainstpotentiallyfatalinfectiousdiseases;avoidingvaccinationraisestheriskofcontractingthosediseasesandspreadingthemtoothers.

15. Dowedoenoughsafetytestingwithvaccines?

Vaccinesaretestedrepeatedlybeforebeingapproved,andcontinuetobemonitoredforadversereactionsaftertheirrelease.Seeourarticleonvaccinetestingandsafetyformoreinformationanddetailsaboutthistopic.

16. Dovaccineshaveabortedfetaltissue?

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No.TherubellavaccinevirusthatisincludedintheMMR(measles,mumpsandrubella)shotisculturedusinghumancelllines.Thevaccinematerialiscarefullyseparatedfromthecellsinwhichiswasgrownbeforebeingused.

Someofthesecelllinesweregeneratedfromfetaltissuethatwasobtainedinthe1960sfromlegalabortions.Nonewfetalissueisrequiredtogeneraterubellavaccine.

17. Isn’tittruethatbetterhygieneandnutritionwereresponsiblefordecreasesindeathsanddiseaserates,ratherthanvaccines?

Improvedhygieneandnutrition,amongotherfactors,cancertainlylowertheincidenceofsomediseases.Datadocumentingthenumberofcasesofadiseasebeforeandaftertheintroductionofavaccine,however,demonstratethatvaccinesareoverwhelminglyresponsibleforthelargestdropsindiseaserates.Measlescases,forexample,numberedanywherefrom300,000to800,000ayearintheUnitedStatesbetween1950and1963,whenanewlylicensedmeaslesvaccinewentintowidespreaduse.By1965,U.S.measlescaseswerebeginningadramaticdrop.In1968about22,000caseswerereported(adropof97.25%fromtheheightof800,000casesinjustthreeyears);by1998,thenumberofcasesaveragedabout100peryearorless.Asimilarpost-vaccinationdropoccurredwithmostdiseasesforwhichvaccinesareavailable.

Perhapsthebestevidencethatvaccines,andnothygieneandnutrition,areresponsibleforthesharpdropindiseaseanddeathratesischickenpox.Ifhygieneandnutritionalonewereenoughtopreventinfectiousdiseases,chickenpoxrateswouldhavedroppedlongbeforetheintroductionofthevaricellavaccine,whichwasnotavailableuntilthemid-1990s.Instead,thenumberofchickenpoxcasesintheUnitedStatesintheearly1990s,beforethevaccinewasintroducedin1995,wasaboutfourmillionayear.By2004,thediseaseincidencehaddroppedbyabout85%.

18. Whycan’tweeradicateotherdiseases,aswedidwithsmallpox?

Intheory,nearlyanyinfectiousdiseaseforwhichaneffectivevaccineexistsshouldbeeradicable.Withsufficientvaccinationlevelsandcoordinationbetweenpublichealthorganizations,adiseasecanbepreventedfromgainingafootholdanywhere;eventually,withoutanyonetoinfect,itmustdieoff.(Anotableexceptionistetanus,whichisinfectiousbutnotcontagious:it’scausedbyabacteriumcommonlyfoundinanimalfeces,amongotherplaces.Thus,tetanuscouldnotbeeradicatedwithoutcompletelyremovingtheClostridiumtetanibacteriumfromtheplanet.)

Smallpoxisunusual,however,inthesetofcharacteristicsthatmadeitsusceptibletoeradication.Unlikemanyotherinfectiousdiseases,smallpoxhasnoanimalreservoir.Thatis,itcan’t“hide”inananimalpopulationandre-emergetoinfecthumans,whilesomediseasescandojustthat(yellowfever,forexample,caninfectsomeprimates;ifamosquitothenbitesaninfectedprimate,itcantransmitthevirusbacktohumans).

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Anotherobstacletoeradicationformanyinfectiousdiseasesisvisibility.Peoplewithsmallpoxwerehighlyvisible:thesmallpoxrashwaseasilyrecognizable,sothatnewcasescouldbedetectedquickly.Vaccinationeffortscouldbefocusedbasedonthelocationofthecasesandpotentialexposuretootherindividuals.Polio,bycontrast,causesnovisiblesymptomsinabout90%ofthepeopleitinfects.Asaresult,trackingthespreadofthepoliovirusisextremelydifficult,whichmakesitadifficulteradicationtarget.

Perhapsmostimportantly,smallpoxpatientsgenerallydidnotreachtheirhighestlevelofinfectivity(thatis,theirabilitytoinfectothers)untilaftertheappearanceofthesmallpoxrash.Asaresult,quickactiontoquarantineinfectedindividualsupontheeruptionoftherashusuallyleftenoughtimetovaccinateanyonewhohadalreadybeenexposed,andpreventadditionalexposures.Manyinfectiousdiseasesdonotallowforthiskindofreactiontime.Measlespatients,forexample,canbecomeinfectiousuptofourdaysbeforetheappearanceofthemeaslesrash.Asaresult,theycanpassthevirusontomany,manyotherpeoplebeforeanyoneevenknowsthattheyareinfected.

Manypeoplestillthinkeradicationispossibleforcertaindiseases.EffortsareongoingtoeradicatepolioandGuineawormdisease(Dracunculiasis),withbothhavingbeeneliminatedinmanyregions,butremainingendemicinseveralcountries.Meanwhile,theCarterCenterInternationalTaskForceforDiseaseEradicationhasdeclaredadditionaldiseasesaspotentiallyeradicable:lymphaticfilariasis(Elephantiasis),mumps,porktapeworm,andyaws.[3]

[Formoreaboutthistopic,seeourarticleondiseaseeradication.]

19. IsthepoliovaccinelinkedtoHIV?

Inthe1990s,certaincriticsbegantoblamethetestingofalive,weakenedpoliovaccineinAfricainthe1950sforthespreadofacquiredimmunedeficiencysyndrome(AIDS).Thosebehindtheaccusationarguedthatchimpanzeecellswereusedtocreatethevaccine,andthatthosecellshadbeencontaminatedwithavirusthatsometimesaffectschimps:simianimmunodeficiencyvirus,orSIV.WhenthevaccinewasgiventochildreninAfrica,theyargued,SIVmutatedtobecomehumanimmunodeficiencyvirus,orHIV,whichcausesAIDS.

Theaccusations,however,weredemonstrablyfalseforavarietyofreasons.Mostnotably,theweakenedpoliovaccinewasnotmadewithchimpanzeecells,butwithmonkeycells.ThevaccinewaslatertestedusingatechniquethatcandetectviralDNA(thePCRtechnique,orpolymerasechainreaction);itdidnotcontainSIVorHIV.

ResearchersattheUniversityofBirminghaminAlabamademonstratedin2006thatwhileHIVwasinfactaderivativeofSIV,chimpanzeesinCameroonthathadbeeninfectedwithSIVinthe1930swerethemostlikelysourceoftheAIDSepidemic—decadesbeforetheweakenedpoliovaccinewastestedinAfrica.

20. Isthepoliovaccinelinkedwithcancer?

ThepoliovaccinesdevelopedbyJonasSalkandAlbertSabininthemid-20thcenturyweremadewithmonkeycells.Yearslater,microbiologistMauriceHillemanfoundamonkeyvirusinbothvaccines—the40thmonkeyvirustobediscovered,whichhecalledSimianVirus40(SV40).(Salk’skilledvaccine,whichhadbeentreatedwithformaldehyde,hadverysmallamountsofthevirus;

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Sabin’slivevaccinewasheavilycontaminated.)Worriedaboutthepotentialeffectstheviruscouldhaveonhumans,Hillemaninjecteditintohamsters,findingthatnearlyallofthemdevelopedmassivecanceroustumors.Buttheinitialpanicthiscausedgavewayinthefaceoffuturestudies.

First,hamstersthatingestedSV40insteadofbeinginjectedwithitdidn’tgetcancer.Sabin’slivevaccine(whichcontainedmoreSV40thanSalk’s)wasgivenorally.AdditionalstudiesshowedthatchildrenwhoweregivenSabin’svaccinedidnotdevelopantibodiestoSV40;itsimplypassedthroughtheirdigestivesystem,nevercausinginfection.

ThatleftonlySalk’svaccine,whichcontainedverylittleSV40,butwasgivenbyinjection.Studiesperformedeightyears,fifteenyears,andthirtyyearsafterSV40-contaminatedvaccineshadbeengiventochildrenfoundthattheyhadthesamecancerincidenceasunvaccinatedgroups.NocredibleevidencesuggeststhatSV40hasevercausedcancerinhumans.

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Cellvsvirushttps://www.youtube.com/watch?v=oqGuJhOeMekWhatcausesantibioticresistance?https://www.youtube.com/watch?v=znnp-Ivj2ek

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Pg.117CheckingConceptsSelectAnswers 1. When Montagu was travelling through Turkey, she noticed women making a small scratch on their children’s arms, then adding a small droplet of pus from a patient who had a mild case of smallpox. This procedure seemed to protect the children from the more extreme symptoms of the disease. 2. The symptoms of an allergy can range from a runny nose to anaphylactic shock.

3. A vaccine is a special version of an antigen that gives you immunity against the disease. 6. Booster shots are given to prolong immunity. 7. Antihistamines reduce the symptoms caused by histamines. These symptoms include a runny nose and watery eyes. 8. An allergy is an unusually high sensitivity to some substance. An allergen is any substance that causes an allergic reaction. 10. HIV is the virus that attacks the immune system by infecting helper T cells. Since the immune system is compromised, infected individuals are susceptible to a variety of secondary infections. Once the immune system has been compromised, the individual is said to have AIDS. HIV is the cause of AIDS. 11. (a) Eat a well-balanced diet. (b) Wash your hands frequently. (c) Keep your home clean 12. Students’ answers may vary but could include the following: (a) You could increase your daily intake of vegetables while reducing the amount of fast food that you eat. (b) Wash your hands for at least 20 seconds to ensure that they are clean. Wash your hands before eating. (c) Vacuum your house frequently. Wash surfaces in the washroom with disinfectants more often. (d) Avoid second-hand smoke by avoiding areas where people are likely to smoke. Ask people around you not to smoke if you have to work in that area. (e) Exercise 5 days a week and get 8 hours of sleep a night. (f) Keep aware of new vaccinations. (Vaccines for chicken pox and hepatitis A/B are fairly recent.) Remain aware of the vaccines you should be taking if you should go travelling in other countries. (g) Don’t share drinks or food with friends.

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Understanding Key Ideas 14. (a) Jenner and Montagu both observed that by infecting people with less virulent variants of smallpox, they could protect them against the deadly disease. b) A vaccine is a special form of the antigen that allows your immune system to develop resistance to the disease. (c) An allergy is an immune response an individual has to a substance called an allergen. The allergen does not stimulate the immune system of most people. (d) HIV is the virus that results in AIDS. The virus attacks helper T cells, seriously compromising the immune system. People with AIDS suffer and may die from secondary infections such as pneumonia. 15. Vaccines will result in the production of memory B cells. These cells may have a limited life span in your body. A booster shot would cause more of these memory B cells to be produced and extend your immunity to the disease. 16. HIV invades helper T cells. Helper T cells activate B cells that produce infection fighting antibodies. Without helper T cells, the defence offered by the B cells is seriously compromised. Pathogens normally attacked by antibodies can now infect AIDS patients with little interference.

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Chapter3–ImmuneSystemReviewName:

A. Withyourpartner,createashort,pointformsummaryofthekeyideasfromthischapter.1.Transmissionofinfectiousdiseases 2.Firstlineofdefense

3.Secondlineofdefense–Innateresponse 4.Secondlineofdefense–Acquiredresponse

5.Vaccines 6.Disordersoftheimmunesystem

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B. Answerthefollowingquestions:

1. HowdidJosephLister’shypothesiseventuallyhelptoreducethenumberofdeathsaftersurgery?2. Intermsofinfectiousdiseases,whyisitagoodideatocoveryourmouthwhenyoucough?3. Ifbacteriagetintothestomachofahuman,whatfirstlineofdefenceoftheimmunesystemwill

potentiallystopthebacteria?4. Whyisthepresenceofphagocytesanindicationofaninfectionbyapathogen?5. Arrangethefollowingstatementsinthecorrectordertodescribetheacquiredimmuneresponseof

theimmunesystemtoapathogen.

a) Antibodiesdestroypathogenb) Bcellsmobilizetoproduceantibodiesc) Someimmunityremainsforfutureused) Pathogenisrecognized

6. WhatarethedifferencesbetweenaBcellandamemoryBcell?

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7. HowisthefunctionofakillerTcelldifferentfromthatofahelperTcell?8. WhatpartoftheimmunesystemdoesHIVattack?9. Afterapersonreceivesavaccination,thebodyproducesantibodiesfortheantigensofaparticular

disease.Howdoestheimmunesystemreactifthevaccinatedpersonbecomesinfectedwiththatdisease?

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Chapter3–ImmuneSystemReviewName:KEY1.Transmissionofinfectiousdiseases•Infectiousdiseasesarecausedbypathogens.•Infectiousdiseasecanbetransmittedbydirectcontact,indirectcontact,contaminatedwaterandfood,andanimalbites.

2.Firstlineofdefense•Theimmunesystemattacksanddestroysinvaderssuchaspathogensandantigensthatenterthebody.•Theimmunesystem’sfirstlineofdefenceistheskinandliningsofthebody’sinternalsystems.

3.Secondlineofdefense–Innateresponse•Theimmunesystem’ssecondlineofdefencemaybeaninnateimmuneresponse,whichisaresponsethatisgeneralandnon-specific.•Thefirstactionoftheinnateimmuneresponseisinflammation.•Whitebloodcellsfightinfectionbyconsuminginvadingpathogens.

4.Secondlineofdefense–Acquiredresponse•Theacquiredimmuneresponseinvolvesfoursteps;recognition,mobilization,disposal,andimmunity.•Bcellsrecognizeantigensandproduceantibodiesinresponse.Antibodiesattachtoantigensandsignalwhitebloodcellstodestroytheantigen.•Antibodiesremaininthebodytoprotectagainstfutureinfections,forming

5.Vaccines•Vaccinesareweakenedversionsofadiseasepathogen.•Vaccinesstimulatetheimmunesystemtocreateantibodies,providingthebodywithimmunityagainstthedisease.

6.Disordersoftheimmunesystem•Immunesystemdisordersoccurwhentheimmunesystemmalfunctionsandworksagainstthebodyitissupposedtoprotect.•Allergiesareanunusuallyhighsensitivitytoasubstance.•AIDSisaninfectionoftheimmunesystemcausedbyHIV.HIVdestroystheimmunesystem,leavingapersonvulnerabletootherdiseases.

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(Q’sfromChaptercheckonpg.118)1. HowdidJosephLister’shypothesiseventuallyhelptoreducethenumberofdeathsaftersurgery?Surgeonsstartedsterilizingequipmentbeforeandaftersurgeryleadingtolessinfectionsandlessdeaths.2. Intermsofinfectiousdiseases,whyisitagoodideatocoveryourmouthwhenyoucough?Pathogens can be spread over 5 m by a cough or a sneeze. By covering your mouth, you reduce the distance the pathogen can travel 3. Ifbacteriagetintothestomachofahuman,whatfirstlineofdefenceoftheimmunesystemwill

potentiallystopthebacteria?The stomach produces gastric juice, which is very acidic and can destroy bacteria. 4. Whyisthepresenceofphagocytesanindicationofaninfectionbyapathogen?Phagocytes are present throughout the body, and they will congregate in areas of infection. When these areas are sampled, the white blood cell count will be elevated. 5. Arrangethefollowingstatementsinthecorrectordertodescribetheacquiredimmuneresponseof

theimmunesystemtoapathogen.

a) Antibodiesdestroypathogenb) Bcellsmobilizetoproduceantibodiesc) Someimmunityremainsforfutureused) Pathogenisrecognized

(d) Pathogen is recognized. (b) B cells mobilize to produce antibodies. (a) Antibodies destroy pathogens. (c) Some immunity remains for future use. 6. WhatarethedifferencesbetweenaBcellandamemoryBcell?B cells actively produce antibodies when fighting an infection, while memory cells are not involved with fighting the pathogen. Memory cells remain after the pathogen has been destroyed so that the body has long term immunity against the pathogen

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7. HowisthefunctionofakillerTcelldifferentfromthatofahelperTcell?Helper T cells activate the B cells, which then produce antibodies that attack the pathogen directly. Killer T cells kill body cells that have become invaded by the pathogen. Killer T cells can also kill cancer cells. 8. WhatpartoftheimmunesystemdoesHIVattack?HIV attacks helper T cells. This means that B cells and killer T cells will not be activated and will therefore not be available to fight secondary infections such as pneumonia. 9. Afterapersonreceivesavaccination,thebodyproducesantibodiesfortheantigensofaparticular

disease.Howdoestheimmunesystemreactifthevaccinatedpersonbecomesinfectedwiththatdisease?

Your immune system has memory B cells that divide, producing many antibody-producing B cells. The antibody-producing B cells release their antibodies, destroying the pathogen.

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Project…Chooseanantibiotic:Whatinfectiondoesthiskill?Doesitkillorpreventthebacteriafromgrowingorreproducing.Whenwasitdiscovered?Whodiscoveredit?Antibioticresistantbacteria..