Vaccines

Vaccines

1. Dr. P. Saranraj
Head
Department of Microbiology
Sacred Heart College (Autonomous)
Tirupattur –635 601
Tamil Nadu, India
Mobile: [phone]; E.mail:
[email protected]
VACCINES

2. VACCINES
Vaccine,isasuspensionofweakened,killed,or
fragmented microbes ortoxinsor
ofantibodiesorlymphocytesthatis
administeredprimarilytopreventdisease.
AvaccinecanconferActiveimmunity
(Artificialactiveimmunity)againstaspecific
harmfulagentbystimulatingtheImmune
systemtoattacktheagent.
Theterm''vaccine''wasderivedin1796fromthe
EdwardJenner'suseoftheterm''Cowpox''
(Latin'‘variolaevaccinia'').
EdwardJennerwasthepioneerofusingCow
poxpustulestopreventsmallpoxinfections
(Variolation).

3. VaccinescanbeProphylactic(example:to
preventoramelioratetheeffectsofa
futureinfectionbyanaturalor
"wild" pathogen),
orTherapeutic(e.g.,vaccinesagainst
cancerarebeinginvestigated).
Theadministrationofvaccinesis
calledVaccination.Vaccinationisthemost
effectivemethodofpreventinginfectious
diseases.
Vaccinationgivenduringchildhoodis
generallysafe.
Adverseeffectsifanyaregenerallymild.
Somecommonsideeffectsincludefever,

4. LIVE ATTENUATED VACCINES
LiveAttenuatedVaccine(LAV)-Avaccine
preparedfromlivingmicroorganismsthathavebeen
weakenedunderlaboratoryconditions(Tissue
culture,EmbryonatedeggsandLiveanimals).They
willgrowandreplicateinavaccinated
individual,butbecausetheyareweak,theywill
causenoorverymilddisease.
Examples-Viral:Measles,Mumps&Rubella
(MMR)(Combinedvaccine)vaccine,Influenza
vaccine (nasalspray),Chicken pox
vaccine,Smallpoxvaccine,OralAdenovirus
vaccine,OralPoliovaccine(Sabin),Rotavirus
vaccine,ShinglesvaccineandYellowfevervaccine.
Bacterial:BacillusCalmette–Guerin(BCG)
vaccine (forTuberculosis)(Attenuated

5. Administration of Attenuated Vaccines
InanAttenuatedvaccine,livevirusparticles
withverylowvirulenceareadministered.
Theywillreproduce,butveryslowly.Sincethey
doreproduceandcontinuetopresentantigen
beyondtheinitialvaccination,boostersare
requiredlessoften(Adjuvants).
Thesevaccinesareproducedbygrowingthe
virusinTissueculturesthatwillselectforless
virulentstrains,orbyMutagenesisorTargeted
deletionsingenesrequiredforvirulence.There
isasmallriskofreversiontovirulence;this
riskissmallerinvaccineswithdeletions.
Attenuatedvaccinesalsocannotbeused
byImmunocompromised individuals.

6. Advantages of Attenuated Vaccines
ActivatesallphasesoftheImmunesystem(for
instanceIgAlocalantibodiesareproduced).
Providesmoredurableimmunity;boostersare
requiredlessfrequently(exceptOPV).
LowcostandQuickimmunity.
Easy to administer (for
instanceOPVforPoliocanbetakenorally,
ratherthanrequiringasterileinjectionbya
trainedhealthworker,astheinactivatedformIPV
dose).
VaccineshavestrongbeneficialNon-specific
effects(Theeffectswhichgobeyondthe
specificprotectiveeffectsagainstthetargeted
diseases).

7. Disadvantages of Attenuated Vaccines
Secondarymutationcancauseareversionto
virulence.Forthisreason,OPVisnolongerused
intheUnitedStates,andhasbeenreplacedon
theRecommended ChildhoodImmunization
SchedulebytheInactivatedpoliovaccine(IPV).
Severe complications
inImmunocompromised patients.
Somecanbedifficulttotransportdueto
requirement to maintain conditions
(e.g.temperature)

8. INACTIVATED OR KILLED VACCINES
Vaccinesofthistypearecreatedby
inactivatingapathogen,typicallyusing
heatorchemicalssuchasformaldehyde
orformalin.Thisdestroysthepathogen’s
abilitytoreplicate,butkeepsit“intact”so
thattheimmunesystemcanstillrecognize
it.
Example–Virus:Poliovaccine(Salk
vaccine),HepatitisAvaccine,Rabies
vaccine,JapaneseEncephalitisvaccineand
Influenzavaccine.Bacteria:Inactivated
Typhoidvaccine,InactivatedCholera
vaccine,PlaguevaccineandDiptheria,

9. Inactivatedvaccinesarefurtherclassified
dependingonthemethodusedto
inactivatethevirus.Theyare(i)Whole
virusandvaccines,(ii)Splitvirusvaccines.
(i)Wholevirusvaccinesusetheentire
virusparticle,fullydestroyedusingheat,
chemicals,orradiation.
(ii)Splitvirusvaccinesareproducedby
usingadetergenttodisruptthevirus.

10. SUBUNIT VACCINE
Subunitvaccinesarevaccinesthatuseonly
partofthedisease-causingvirus.
Onepartofthevirusisresponsiblefor
creatingdisease.Thepartresponsiblefor
creatingdiseaseisaprotein,whichwecall
theantigen.Subunitvaccinescancontainfrom
1to20antigens,thatareeithertakendirectly
fromthevirus,orgrowninthelabusingthevirus
DNA.
SomeofthecommonlyusedSubunitvaccines–
Bacteria:AcellularPertussisvaccine.Virus:
HepatitisBVaccineandHumanPapilomaVirus
(HPV)vaccine.
Vaccinesmadeusingantigensgrowninthelab

11. AnexampleoftheRecombinantsubunitvaccine
istheHepatitisBvirusvaccine.TheHepatitis
Bgenesthatcodefortheantigenswereinserted
intocommonBaker’syeast.Thatyeastgrewand
expressedthegenesandproducedtheantigen
protein.Scientistswerethenabletocollectand
purifytheproteinantigen,whichwasusedforthe
vaccine.
Vicapsularpolysaccharidevaccine(ViCPS)is
another Subunit vaccine (contains
polysaccharidelinkedtotheVicapsularantigen),
inthiscase,againstTyphoidcausedbytheTyphi
serotypeofSalmonella.Itisalsocalleda
Conjugatevaccine,inwhichapolysaccharide
antigenhasbeencovalentlyattachedtoa

12. Advantages of Subunit Vaccines
Subunitvaccinescanbegiventopeople
withweakenedimmunesystems.
Thesevaccinesappeartogivelong-lived
immunity.
Sinceonlypartsofthevirusareusedforthese
vaccines,therisksofreactionsareverylow.
DisadvantagesofSubunitVaccines
Severaldosesmustbegivenforproperlife-long
immunity

13. DNA VACCINE
DNAvaccinationisatechniqueforprotecting
againstdiseasebyinjectionwithgenetically
engineeredDNA(PlasmidDNA)socellsdirectly
produce an antigen,producing a
protectiveimmunologicalresponse.
MusclecellstakeuptheDNAandtheencoded
proteinantigenisexpressed,leadingtobotha
HumoralantibodyresponseandaCell-mediated
response.
SeveralDNA vaccinesareavailable
forVeterinaryuse.CurrentlynoDNAvaccines
havebeenapprovedforhumanuse.
A veterinary DNA vaccine to
protecthorsesfromWestNilevirus(ssRNA

14. Animprovedmethodforadministeringthese
vaccinesentailscoatingmicroscopicgoldbeads
withtheplasmidDNAandthendeliveringthe
coatedparticlesthroughtheskinintothe
underlyingmusclewithanairgun(calledaGene
gun).Thiswillallowrapiddeliveryofavaccineto
largepopulationswithouttherequirementfor
hugesuppliesofneedlesandsyringes.
ResearchofDNAVaccineisunderway
forviral,bacterialandparasiticdiseasesin
humans,aswellasforseveralcancers.

15. Advantages of DNA Vaccines
Noriskforinfection
AntigenpresentationbybothMHCmolecules
Easeofdevelopmentandproduction
Stabilityforstorageandshipping
Long-termpersistenceofimmunogen
Encodedproteinisexpressedinthehostinitsnatural
form-thereisnodenaturationormodification.
Refrigerationisnotrequiredforthehandlingandstorage
oftheplasmidDNA,afeaturethatgreatlylowersthecost
andcomplexityofdelivery.
DNAvaccinesalsoinducebothHumoralandCell-
mediatedimmunity.
DNAvaccinescauseprolongedexpressionofthe
antigen,whichgeneratessignificantimmunological
memory.

16. Disadvantages of DNA Vaccines
Limitedtoproteinimmunogens(notusefulfor
non-proteinbasedantigenssuchasbacterial
polysaccharides)
Riskofaffectinggenescontrollingcellgrowth
Possibilityofinducingantibodyproduction
againstDNA
Possibilityoftolerancetotheantigen(protein)
produced
Potentialforatypicalprocessingofbacterialand
parasiteproteins

17. SYNTHETIC PEPTIDE VACCINE
Synthetic peptide vaccine is
avaccineconsistingmainlyof20to30
syntheticpeptides.
Syntheticpeptidevaccineareusuallyconsidered
tobesaferthanvaccinesfrommicrobialcultures.
Creatingvaccinessyntheticallyhastheabilityto
increasethespeedofproduction.Thisis
especiallyimportantintheeventofapandemic.
Theworld'sfirstsyntheticvaccinewascreatedin
1982fromDiphtheriatoxinbyLouisChedid
(scientist)fromthePasteurInstitute(Paris,
France)andMichaelSelafromtheWeizmann
Institute(Rehovot,Israel).
In1986,ManuelElkinPatarroyocreated

18. Advantages of Synthetic peptide Vaccines
Antigensarepreciselydefinedandfreefrom
unnecessarycomponentswhichmaybe
associatedwithsideeffects.
Stableandrelativelycheaptomanufacture.
Lessqualityassuranceisrequired.
Changesduetonaturalvariationoftheviruscan
bereadilyaccommodated,whichwouldbea
greatadvantageforunstablevirusessuchas
influenza.
Lesstoxic.
Productionandqualitycontrolisverysimple.

19. Disadvantages of Synthetic Peptide Vaccines
SyntheticpeptidesdonotreadilystimulateT
cells.
Syntheticpeptidesarenotapplicabletoall
viruses.
Maybelessimmunogenicthanconventional
inactivatedwhole-virusvaccines.
RequiresAdjuvant
FailstoelicitCellMediatedImmunity

20. ANTI-IDIOTYPE VACCINE
Avaccinemadeofantibodiesthatseeother
antibodiesastheantigenandbindtoit.
Anti-idiotypevaccinescanstimulatethebodyto
produceantibodiesagainsttumorcells.
Anti-idiotypeantibody(AId)istheanti-antibody
aimingatgroup-specificantigenEpitopeoftheV
regionoftheantibodymolecule.
Anti-idiotypic
vaccinescompriseantibodiesthathave3D
immunogenicregions,designatedidiotopes,that
consistofproteinsequencesthatbindtocell
receptors. Idiotopesare aggregated
intoidiotypesspecificoftheirtargetantigen.An
example of anti-idiotype antibody

21. Anti-idiotypeantibodyvaccineisanewtypeof
immunebiologicswhichwasdevelopedinthe
late1970s.Itdevelopedtowardspracticalareas
andithadabigthroughinitsproductionof
vaccines,treatmentofcancerandsoon.
Anti-idiotypeshavemanypotentialusesasviral
vaccines,particularlywhentheantigenisdifficult
togroworhazardous.Theyhavebeenusedto
induceimmunityagainstawiderangeofviruses,
includingHepatitis–B,Rabies,Newcastle
diseasevirusandReovirusesandPolioviruses.

22. VACCINATION SCHEDULE

23. TOXOIDS
Toxoidvaccinesarevaccinesthataremade
fromthetoxins(harmfulchemicals)from
bacteria.
Somebacteriathatcausediseasethrough
releasingaproteincalledatoxin.Scientists
caninactivatethesetoxinsinthelabusinga
chemicalcalledformalinandsterilizedwater,
whicharecompletelysafetouseinsmall
quantitiesinthehumanbody.
Oncethetoxinisinactivated,it’scalleda
toxoid,anditcannolongercauseharm.The
bodylearnshowtofightoffthebacteria’snatural
toxinonceexposedtothetoxoidthrough
producingantibodiesthatbindintothetoxinlike

24. Ininternationalmedicalliterature,theToxoid
preparation also is known
asAnatoxinorAnatoxine.
ExampleforToxoidsorToxoidvaccines-
Diphtheria toxoid, Tetanus
toxoidandBotulismtoxoid.
Toxoidscanactuallybeconsideredkilledor
inactivatedvaccines,butaresometimesgiven
theirowncategorytohighlightthefactthatthey
containaninactivatedtoxin,andnotan
inactivatedformofbacteria.