Medical Microbiology

32 1 GeneralAspectsofMedicalMicrobiology

Table 1. 12 VaccineGroupsUsedinActiveImmunization

Vaccinegroup Remarks

Killedpathogens Vaccinationprotectionoftennotoptimum,vaccination

hastoberepeatedseveraltimes

Livingpathogenswith

reducedvirulence

(attenuated)

Optimumvaccinationprotection;asingleapplication

oftensuffices,sincethemicroorganismsreproducein

thevaccinatedperson,providingverygoodstimulation

oftheimmunesystem;donotuseinimmunocompro-

misedpersonsandduringpregnancy(someexceptions)

Purifiedmicrobial

immunogens

• Proteins Oftenrecombinantantigens,i.e.,geneticallyengineered
  proteins;well-knownexample:hepatitisBsurface(HBs)
  antigen


• Polysaccharides Chemicallypurifiedcapsularpolysaccharidesofpneu-
  mococci,meningococci,andHaemophilusinfluenzaese-
  rotypeb;problem:theseareTcell-independentantigens
  thatdonotstimulateantibodyproductioninchildren
  youngerthantwoyearsofage


• Conjugatevaccines Couplingofbacterialcapsularpolysaccharideepitopesto
  proteins,e.g.,totetanustoxoid,diphtheriatoxoid,or
  proteinsoftheoutermembranesofmeningococci;chil-
  drenbetweentheagesoftwomonthsandtwoyears
  canalsobevaccinatedagainstpolysaccharideepitopes
  Toxoids Bacterialtoxinsdetoxifiedbyformaldehydetreatment
  thatstillretaintheirimmunogenfunction
  Experimentalvaccines DNAvaccines.PurifiedDNAthatcodesfortheviral
  antigens(proteins)andisintegratedinplasmidDNAor
  nonreplicatingviralvectorDNA.Thevectormusthave
  geneticelements—forexampleatranscriptionalpromo-
  terandRNA-processingelements—thatenableexpres-
  sionoftheinsertinthecellsofvarioustissues(epider-
  mis,musclecells)
  Anti-idiotype-specificmonoclonalantibodies
  Vacciniavirusesascarriersofforeigngenesthatcodefor
  immunogens

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Kayser, Medical Microbiology © 2005 Thieme