P gingivalis

p gingivalis seminar

1. P GINGIVALIS
Drpmikitha
Iimds
Deptofperiodontology
Aecsmaaruticollegeofdentalsciencesandresearchcentre

2. Session 1
CONTENTS
Introduction
Taxonomy
Biochemicalcharacteristics
Bacterialstructureofp.gingivalis
Microbiologicaltests
Oralecology
Transmission
P.gingivalisinhumanperiodontaldisease:occurrence&treatment
Virulencefactors

3. INTRODUCTION
Periodontaldiseasescompriseagroupofinfectionsinvolvingthe
supportingtissuesoftheteeth,theserangeinseverityfrommildand
reversibleinflammationofthegingivatochronicdestructionof
periodontaltissueswitheventualexfoliationofteeth.
Thebacterialetiologyiscomplex,withavarietyoforganismsresponsible
fortheinitiationandprogressionofdisease.
Theclassificationofthevariousmanifestationsofperiodontaldiseasesis
continuallychanging.
Thenatureofthepathogenicagentsvariesamongthesediseaseentities,
aswellasamongpatientsandevenbetweendifferentdiseasesiteswithin
apatient.

4. TAXONOMY
Family Bacteroidaceae
genera Bacteriods
Fusobacterium
Leptotrichia
Emergence of the genus Porphyromonas and taxonomic position of
P. gingivalis
HowKHetal.Lifebelowthegumline:PathogenicmechanismsofPg.MicrobiologyandMolecularBiologyReviews,December1998,1244-1263.

6. BIOCHEMICAL PROPERTIES
Asaccharyolytic&anaerobic
Salivaandmucousmembranes–temporarytransitionphase
Subgingivalecosystemisideal
Nutrients- Redoxpotential
Peptides&aa
VitK,VitB12&heme
HowKHetal.Lifebelowthegumline:PathogenicmechanismsofPg.MicrobiologyandMolecularBiologyReviews,December1998,1244-1263.

7. Structure of P Gingivalis

8. MICROBIOLOGICAL TESTS

9. Sampling techniques
Subgingivalplaque-
Mombellietal(1991)showedthat4individualsubgingival
specimens,eachfromthedeepestperiodontalpocketineach
quadrant,shouldbeincludedtodetectPg
Christerssonetal(1992)alsoshowedthatsampling3pocketswith5
mmorgreaterpocketdepthprovidedaprobabilityof95%of
detectingPg
Wholesalivasampleseemstobeareasonablygoodsubstitutefor
subgingivalsamples
HowKHetal.Lifebelowthegumline:PathogenicmechanismsofPg.MicrobiologyandMolecularBiologyReviews,December1998,1244-1263.

10. Current methods for detection
Method Molecular targetDetection limit
Culture 0.1-0.2% of total viable
count
Immunodiagnostic
Indirect immunofluorescencePolyclonal
antibodies to
whole-cell
antigens
500 cells/ml
HowKHetal.Lifebelowthegumline:PathogenicmechanismsofPg.MicrobiologyandMolecularBiologyReviews,December1998,1244-1263.

11. Flow cytometry
Evalusite
Bacterial
concentration flow
cytometry
Monoclonal
antibodies to
LPS
Polyclonal
antibodies to
serotype
antigens
Monoclonal
antibodies to
whole-cell
antigens
100 cells/ml
10
6
cells
10
4
cells
HowKHetal.Lifebelowthegumline:PathogenicmechanismsofPg.MicrobiologyandMolecularBiologyReviews,December1998,1244-1263.

12. Nucleic acid probe
Digoxigenin-labled
whole genomic probeGenomic DNA 10
3
cells
DMDx Genomic DNA
Radiolabeled
oligonucleotide
16SrRNA genes 10
3
cells
PCR 16SrRNA genes 25-100 cells
Nested PCR Space region bw
16SrRNA & 23rRNA
genes
10 cells
HowKHetal.Lifebelowthegumline:PathogenicmechanismsofPg.MicrobiologyandMolecularBiologyReviews,December1998,1244-1263.

13. Multiplex PCR 16SrRNA genes 5-50 cells
Immunodiagnostic Specific Pg DNA
region of unknown
functions
16 cells
HowKHetal.Lifebelowthegumline:PathogenicmechanismsofPg.MicrobiologyandMolecularBiologyReviews,December1998,1244-1263.

14. CULTURE
Nonselective
Selective
Growinculturemediaformingconvex,smoothglossycoloniesof1-
2mmdiameter,whichdemonstrateaprogressivedarkeninginthe
center,becauseofproductionofprotoheme,thesubstance
responsibleforthetypicalcolorofthesecolonies
HowKHetal.Lifebelowthegumline:PathogenicmechanismsofPg.MicrobiologyandMolecularBiologyReviews,December1998,1244-1263.

16. BANA
Tf,Pg,Tdandcapnocytophagaspecieshaveatrypsin-likeenzymein
common
Activityoftheenzymecanbemeasuredwiththehydrolysisofthe
colorlesssubstrateBANA
Diagnostickit–Perioscan
Loescheetal(1992)andBecketal(1990)usedthisassayintheirstudy
HowKHetal.Lifebelowthegumline:PathogenicmechanismsofPg.MicrobiologyandMolecularBiologyReviews,December1998,1244-1263.

17. Real-timePCRtechnologyhasdemonstratedahighdegreeofsensitivityand
specificity
Culture,checkerboardanalysisandreal-timequantitativePCRrequire
sophisticatedlabfacilities,laborintensiveandexpensive
Onlycultureenablestostudyofantibacterialsusceptibilitiesanddetectionof
unexpectedbacteria
Todate,thereisnoidealmicrobialdiagnosticforadjunctiveclinicalusein
periodontics
HowKHetal.Lifebelowthegumline:PathogenicmechanismsofPg.MicrobiologyandMolecularBiologyReviews,December1998,1244-1263.

18. ORAL ECOLOGY
&
PERSON-TO-PERSON TRANSMISSION

19. The natural habitat
Noevidencethattheylivefreeinnature
Humanisolatesphenotypicallydifferentfromthoseofothermammals
Occursinpockets&mucosalsurfaces
Notfoundinedentulousbabies&elderlypeople
Donotbelongtotheindigenousmicrobiotaofanyotherbodysite
Cancausenonoralinfections
HowKHetal.Lifebelowthegumline:PathogenicmechanismsofPg.MicrobiologyandMolecularBiologyReviews,December1998,1244-1263.

20. Initial colonization on the tooth surfaces
Doesnotseemtocolonizecleantoothsurface
Preferssitesshowinginflammation,poorOH,&sitesharboringG+
bacteria
Absent/infrequentinprimarydentitionofprimaryteethinhealthy
children
Efficientlyequippedtocolonizesupragingivaltoothsurfaces,
probablyatanyareaofthedentition
HowKHetal.Lifebelowthegumline:PathogenicmechanismsofPg.MicrobiologyandMolecularBiologyReviews,December1998,1244-1263.

21. Distribution pattern within individuals
Widelydistributed,whichmightberelatedtothelackofefficacyinthe
antibodyresponse
OccurrenceofPg+vepatientsincreaseswithage
Thenoteddistributionmayberelatedtotheefficacyofantibody
responseagainstthein.org.IthasbeensuggestedthattheIgGresponse
toAaisprotectandabletolimitinfectionaroundedafewteeth,
whereaselevatedantibodytiterstoPgarenotcapableofcontrollingit,
whichmayleadtogeneralizedperiodontaldestruction
HowKHetal.Lifebelowthegumline:PathogenicmechanismsofPg.MicrobiologyandMolecularBiologyReviews,December1998,1244-1263.

22. Proportionsofflora,balance-imbalance
Inperiodontalhealthysites,presentinverylowproportions
Highproportionsindisease-breakdowninhomeostasis
DifferencebwAa&PgcolonizationwasdemonstratedbyTorkko&
Asikainen(1996)andRamsetal(1997)inAPpatients.Aa-4%inboth,
whereasPg16%&23%respectively
HowKHetal.Lifebelowthegumline:PathogenicmechanismsofPg.MicrobiologyandMolecularBiologyReviews,December1998,1244-1263.

23. Genetic diversity of Pg in nature
Thepopulationgeneticstudyofbacteriaarosefrominterestinevolutionary
processesoforganisms,buthasalsoprovidedimportantinsightintobacterial
pathogenesis
Studiesonpathogenicbacteriahavesuggestedthatmany,butnotall,
bacterialpathogensexistasdiscreteclonesinnature:thatis,thegenetic
changesduetorecombinationoccursoinfrequentlythatthegenotypesof
bacteriaremainstableoversignificantlylongperiodsoftime.Moreover,
specificclonesmayberesponsibleforamajorityofinfectiousdiseases
ascribedtoapathogen
HowKHetal.Lifebelowthegumline:PathogenicmechanismsofPg.MicrobiologyandMolecularBiologyReviews,December1998,1244-1263.

24. Loosetal.(1993)examinedthepopulationgeneticstructureofPgbyusing
multilocusenzymeelectrophoresison88humanPgstrains.
MoststrainsoriginatedinthesubgingivalsitesofAPorotheroralinfections
andonlytwoisolatesinnon-periodontitisindividuals.
TheresultssuggestedthatthepopulationstructureofPgisclonal,with
certainclonesbeingwidespreadingeographicallydiverseregions.No
associationwasfoundbetweenspecificclustersanddiseasetypes
(periodontaldiseases,endodonticinfectionsorotheroralinfections)orthe
abilityofthestrainstocausespreadingorlocalizedinfectionsinthemouse
model.
HowKHetal.Lifebelowthegumline:PathogenicmechanismsofPg.MicrobiologyandMolecularBiologyReviews,December1998,1244-1263.

25. GeneticdiversityofPgwithinindividuals
StudiesonPgshowthatmostindividualsareinfectedwithasingle
cloneofthisspecies
HowKHetal.Lifebelowthegumline:PathogenicmechanismsofPg.MicrobiologyandMolecularBiologyReviews,December1998,1244-1263.

26. Transmission
Thebehaviourofapathogenicmicroorganismdependsuponthe
interactionbetweenthehost,thepathogenandtheenvironment.
Changesinanyofthesefactorswillaffectthelikelihoodof
transmission
Hostfactorsinclude,amongothers,sexualbehaviour,hygiene,
occupation,nutrition,immunityandgeneralhealth.
Microbialfactorsincludeinfectiousness,pathogenicity,virulenceand
survivalinhumanandanimalhosts,includingresistancetowards
immuneresponsesanddrugs.
VanWinkelhoff,A.J.,&Boutaga,K.Transmissionofperiodontalbacteriaandmodelsofinfection.JournalofClinicalPeriodontology.2005;
32(s6),16–27.

27. Environmentalfactorssuchastemperature,humidityandoxygen
tensionaredeterminantsofthesurvivalofmicrobesoutsidethehost.
Whentransmissionisdirectlyfromparentstooffspring(viaovum,
placenta,milk,blood,saliva)itisreferredtoasvertical.
Transmissioniscalledhorizontalwhenanindividualinfects
unrelatedindividualsbycontact,respiratoryorfaecal–oralspread.
VanWinkelhoff,A.J.,&Boutaga,K.Transmissionofperiodontalbacteriaandmodelsofinfection.JournalofClinicalPeriodontology.2005;
32(s6),16–27.

28. Vertical transmission
VerticaltransmissionofP.gingivalismayoccurbuthasonlyrarelybeen
observedbasedongenotypingoftheisolatesfromparentsandchildren.The
Tuite-McDonnelletal.’s(1997)studyhassuggestedthatvertical
transmissionofP.gingivaliscanoccur,butthisstudydoesnotprovide
conclusiveevidenceasgenotypinghasnotbeenperformed.
AstudyconductedbyTiute-McDonnelletal(1997)usedPCRassayto
detectoralPgfrommembersof104randomlyselectedmultigeneration
families.Resultsshowedthatfindinganinfectedfamilymember
substantially,increasedtherelativeriskofdetectingPgfromotherfamily
members.
VanWinkelhoff,A.J.,&Boutaga,K.Transmissionofperiodontalbacteriaandmodelsofinfection.JournalofClinicalPeriodontology.2005;
32(s6),16–27.

29. ThisimpliesintrafamilialtransmissionofPg,althoughitdoesnot
proveit.Itispossiblethatmemberssharehabits,suchaspoorOH
anddeficientdentalcare,whichmayenhancecolonizationofthis
speciesandleadtoacquisitionstrainsfromextrafamilialsourcesas
well.
VanWinkelhoff,A.J.,&Boutaga,K.Transmissionofperiodontalbacteriaandmodelsofinfection.JournalofClinicalPeriodontology.2005;
32(s6),16–27.

30. Horizontal transmission
Canoccurbwsiblingsorspouses
Twostudies,Petitetal(1993)&Saarrela(1996)bothreportedthatsiblings
harboredidenticalgenotypesofPgingivalis.Thereasonsforthestrain
identityinsiblingsmaybethatthesiblingshavetransmittedthestrainto
eachotherorthateachsiblinghasacquiredthestraindirectlyfrom
bacterium-positiveparent.However,thestudydesignsdonotpermit
distinctionbetweenthehorizontalandverticalmodesoftransmission
VanWinkelhoff,A.J.,&Boutaga,K.Transmissionofperiodontalbacteriaandmodelsofinfection.JournalofClinicalPeriodontology.2005;
32(s6),16–27.

31. TransmissionofPgisratheruncommonbetweenspousesinregardtotheir
intimateco-habitanceofseveralyears
P.gingivalisamongcohabitingadultsmaybeinterpretedinseveralways.
Transmissionoccurredmorefrequently,butdidnotleadtopersistent
colonizationordetectablelevelsoftheorganism,methodsdidnotallow
recoveryoftheorganismorofallcolonizingclones,colonizationishost-
dependent,colonizationdependsonthecharacteristicsofthestrain,the
numbersofbacteriainthetransferinoculationweretooloworexposureto
infectionoccurredtoorarely
Theresultsalsosuggestthatestablishedoralmicrobiotadoesnoteasilyaccept
newbacterialinvaders.
VanWinkelhoff,A.J.,&Boutaga,K.Transmissionofperiodontalbacteriaandmodelsofinfection.JournalofClinicalPeriodontology.2005;
32(s6),16–27.

32. Associations between bacteria and disease have been well established for A.
actinomycetemcomitans and P gingivalis .Recent evidence suggested the
possibility that people with periodontitis may cause periodontal breakdown
in their spouses (Von Troil-Linden et al 1995).
The study design included 20 married couples. Two kinds of probands were
selected according to periodontal status. One group of probands exhibited
advanced periodontitis and the other group was periodontally healthy.
The spouses of these probands volunteered to participate in the study. The
inclusion criteria were that the couples were in their middle ages and had
been married for more than ten years.
Clinical significance of transmission
VanWinkelhoff,A.J.,&Boutaga,K.Transmissionofperiodontalbacteriaandmodelsofinfection.JournalofClinicalPeriodontology.2005;
32(s6),16–27.

33. Theresultsshowedthatthespousesofthediseasedprobandshadmore
frequentlydeepperiodontalpockets,radiographicattachmentlossand
periodontalpathogensthanthespousesofthehealthyprobands.The
differencecouldnotbeexplainedbysex,ageorsocialstatus.Neitherwas
thereadifferenceintheleveloforalhygienebetweenthetwospousegroups.
However,differentresultswereobtainedinaseven-yearlongitudinalstudy
onyoungIndonesiancoupleswhohadbeenmarriedforontheaverageoften
years(VanderVeldenetal1996).Theresultsshowedthatthecohabitation
didnotleadtochangeintheperiodontalconditionofthespouse.

VanWinkelhoff,A.J.,&Boutaga,K.Transmissionofperiodontalbacteriaandmodelsofinfection.JournalofClinicalPeriodontology.2005;
32(s6),16–27.

34. Route of infection from person to person
Theroleofsalivaasatransportvehiclehasbeensupportedbythe
findingsthatA.actinomyceterncomitansandPgingivaliscanbecultured
fromsalivarysamples,whichindicatesthatthesebacteriaareableto
surviveinsalivaduringtransportationtoanewhost.
However,comparedwithsalivaryinoculation,mucosalcontactor
sharingatoothbrushmayallowdirectimplantationofbacteriato
potentialgrowthlocales.
HowKHetal.Lifebelowthegumline:PathogenicmechanismsofPg.MicrobiologyandMolecularBiologyReviews,December1998,1244-1263.

35. SalivaisalikelytransportvehiclefortransmittingstrainsofPg,alongwith
manyotherorganisms.Thismayoccurespeciallyeasilytochildren.Salivaof
thecaregivercanbebroughttothechild'smouthwhencaringforayoung
child.Itisnotknownwhatthesizeoftheinoculumisorhowmanyeventsof
exposureareneededtomaximizethepossibilityforsuccess-fully
transmittingPg.
Probabilitythatthehighertheirloadinsaliva,thegreatertheriskof
colonizationoftherecipient.Suppressionoftheorganismsinsalivamay
preventtheirspreadamongindividuals.
PeriodontaltreatmentcansuppresssalivaryAa&Pgunderdetectionlevelor
stronglydecreasetheirnumbersinpatientswithperiodontitisforatleast6
months.
HowKHetal.Lifebelowthegumline:PathogenicmechanismsofPg.MicrobiologyandMolecularBiologyReviews,December1998,1244-1263.

36. Pg IN HUMAN DISEASE: OCCURRENCE & TREATMENT
ThedesignationofAa&Pgasperiodontalpathogenspresupposes
thatdestructiveperiodontaldiseaseismoreprevalentinperiodontal
sitesexposedtotheorganismsthaninnon-exposedperiodontalsites.
Italsoassumesthatfuturedestructiontakesplacemorefrequentlyin
periodontalsitesexposedtotheorganismsthaninthosenotexposed
GriffenAL,BeckerMR,LyonsSR,MoeschbergerML,LeysEL.Prevalenceofporphyromonasgingivalisandperiodontalhealthstatus.JClinMicrobiol1998;36:3239-
42.

37. Subgingivalprevalence of Pg
Mostauthorsagreethatperiodontallyhealthychildrenandadolescents
harborfewornoPgingivalisinthesubgingivalmicrobiota.
However,basedonDNAprobeanalysis,Bimsteinetal.(1996)described
subgingivalPgingivalisinmanyhealthychildren.
Chen&Slots(1999)usedDNAprobeidentificationmayoverestimate
theprevalenceoftheorganismduetocross-hybridizationwithother
subgingivalspecies.
GriffenAL,BeckerMR,LyonsSR,MoeschbergerML,LeysEL.Prevalenceofporphyromonasgingivalisandperiodontalhealthstatus.JClinMicrobiol1998;36:3239-
42.

38. Pgingivalishasbeendescribedin37-63%ofLJPpatients.However,the
organismisrarelyfoundatthedebutofthediseaseandtendstocomprise
onlyasmallpartofthemicrobiotainearlydiseasestages.
Incontrast,PgingivalisisapredominantorganisminGJPandmayassess
pathogeneticsignificanceinthedisease.
Adultshavingahealthyandminimallydiseasedperiodontiumreveal
subgingivalPgingivalisinlessthan10%ofstudysites.
GriffenAL,BeckerMR,LyonsSR,MoeschbergerML,LeysEL.Prevalenceofporphyromonasgingivalisandperiodontalhealthstatus.JClinMicrobiol1998;36:3239-
42.

39. Ontheother40-100%ofAPpatientsmayyieldtheorganism.
Furthermore,Pgcomprisesaconsiderablyhigherproportionof
subgingivalmicrobiotaindeepthaninshallowperiodontalpockets.
ThehighoccurenceofPgingivalisinAPlesionstogetherwiththe
organism'spathogenicpotentialaremainreasonsfordesignatingthe
speciesasaprimepathogenofAP
GriffenAL,BeckerMR,LyonsSR,MoeschbergerML,LeysEL.Prevalenceofporphyromonasgingivalisandperiodontalhealthstatus.JClinMicrobiol1998;36:3239-
42.

40. P gingivalisvirulent strains
Pgingivalisstrainsvaryinpathogenicity.
Basedonexperimentalinfectionsinanimals,Pgingivalisstrainsofhigh
virulencecausedisseminatedinfectionswithseveretissuedamageanddeath
whereaslessvirulentornoninvasivestrainsprodlocalizedabscesswith
mildertissuedamage.
Laine&vanWinkelhoff(1998),studyingthevirulenceofcapsularserotypes
ofPgingivalisinamousemodel,foundencapsulatedstrainstoproduced
phlegmonous,spreadingtypeofinfections,whereaslessvirulentnon-
encapsulatedstrainsproducedlocalizedabscesses
GriffenAL,BeckerMR,LyonsSR,MoeschbergerML,LeysEL.Prevalenceofporphyromonasgingivalisandperiodontalhealthstatus.JClinMicrobiol1998;36:3239-
42.

41. DahlenandSlots(1989)comparingthegrowthandpathogenicityofP
gingivalisstrainsinsubcutaneoustissuechambersimplantedinrabbits,
foundtheorganismtobeparticularvirulentinco-infectionwith
A.actinomycetemcomitans.DifferencesincollagenolyticactivityamongP
gingivalisstrainsmayaccountforsomeoftheobservedvariationinP
gingivalisvirulence.
ThesearchforhighlyvirulentgenotypesofPgingivalishasnotbeenvery
rewarding
GriffenAL,BeckerMR,LyonsSR,MoeschbergerML,LeysEL.Prevalenceofporphyromonasgingivalisandperiodontalhealthstatus.JClinMicrobiol1998;36:3239-
42.

42. Pg in ailing or failing implants & in periodontal infection
Pgingivalisarerareisolatesfromhealthymucosalsitesaroundintegrated
dentalimplants.
Mengeletal.(1996)studied35healthyimplantsitesinfivepartially
edentulouspatientswhohadbeentreatedforsevereperiodontitis.Noneof
theimplantsinthestudyyieldedAaorPg
Pgwasrelatedtoimplantfailureinofstudies.Inanimalstudiesblack-
pigmentedanaerobicrodsincludingPgingivalis-likeorganismswere
associatedwithdevelopmentofligature-inducedperi-implantitisApparently
Pgingivaliscomprisemajorpathogenininfectiousimplantfailure
GriffenAL,BeckerMR,LyonsSR,MoeschbergerML,LeysEL.Prevalenceofporphyromonasgingivalisandperiodontalhealthstatus.JClinMicrobiol1998;36:3239-
42.

43. AactinomycetemcomitansandPgingivaliscanattachtobarrier
membranesandPgingivaliscanpenetrateporousbarriermembranes
onesidetotheother.Bothorganismshavebeenimplicatedinfailing
regenerativeperiodontaltherapy.
Demolonetal.(1993)demonstratedanassociationbetweenP
gingivalisonbarriermembranesandclinicalsignsofgingival
inflammation.
GriffenAL,BeckerMR,LyonsSR,MoeschbergerML,LeysEL.Prevalenceofporphyromonasgingivalisandperiodontalhealthstatus.JClinMicrobiol1998;36:3239-
42.

44. Effect of periodontal treatment on subgingivalPg
Scalingandrootplaningmaycausetemporarydecreaseinlevelsof
subgingivalPgingivalisbutisnotcapableoferadicatingtheorganismfrom
subgingivalsites.
LocationofPgingivalisininaccessibleareas,suchasfurcationsorthebase
ofperiodontalpockets,isprobablyresponsibleforthefailureofmechanical
therapytoremovetheorganism.
GriffenAL,BeckerMR,LyonsSR,MoeschbergerML,LeysEL.Prevalenceofporphyromonasgingivalisandperiodontalhealthstatus.JClinMicrobiol1998;36:3239-
42.

45. Similarly,non-resectiveperiodontalsurgeryisnoteffectiveinremovingP
gingivalisfromadultperiodontitislesions.Surgeryaimedateliminating
periodontalpocketsprovidesamorepredictablesuppressionofPgingivalis,
especiallywhenfollowedbydiligentoralhygiene.
Systemicantimicrobialtherapyincombinationwithnonsurgicalperiodontal
scalingandrootplaningmaynotensuresubgingivaleradicationofP
gingivalis.Neitheristopicalantimicrobialtherapyveryusefulineliminating
Pgingivalisfromdeepperiodontalpocket.ThemosteffectivecontrolofP
gingivalisseemstobeachievedbyemployingacombinationofresective
periodontalsurgery,systemicantibiotictherapyandgoodoralhygiene.
GriffenAL,BeckerMR,LyonsSR,MoeschbergerML,LeysEL.Prevalenceofporphyromonasgingivalisandperiodontalhealthstatus.JClinMicrobiol1998;36:3239-
42.

46. Regenerationofperiodontalconnectiveattachmentiscontingentuponthe
absenceofPgingivalisandotherperiodontalpathogensintreatedsites.
Zarkeshetal(1999)describedamethodofcoatingPTFEbarriermembranes
withtetracycline.Comparedwithnon-coatedbarriermembranes,
tetracycline-coatedmembranespermittedlessPgingivaliscolonizationand
moreclinicalattachmentgain.
GriffenAL,BeckerMR,LyonsSR,MoeschbergerML,LeysEL.Prevalenceofporphyromonasgingivalisandperiodontalhealthstatus.JClinMicrobiol1998;36:3239-
42.

47. PG IN NON-ORAL INFECTIONS

48. VIRULENCE FACTORS

51. CAPSULE
Consideredanimportantvirulencefactorbymany
Somestrainshaveeitherathinlayeroraredevoidofit
Itisformedbyapolysaccharideheteropolymerontheouter
membraneofthebacterialcell(Wooetal.,1979).
HoltSC,KesavaluL,WalkerS,GencoCA.VirulencefactorsofPorphyromonasgingivalis.Periodontol20001999;28:168-238.

52. CHEMICAL COMPOSITION
Differbwstrains
Mansheim&Kasper(1977)-galactose,glucoseandgalactosamine
Okudaetal(1987)-rhamnose,glucose,galactose,mannoseand
methylpentose
HoltSC,KesavaluL,WalkerS,GencoCA.VirulencefactorsofPorphyromonasgingivalis.Periodontol20001999;28:168-238.

53. BIOLOGICAL FUNCTION
Highlyencapsulatedstrainsexhibitdecreasedautoagglutination,
lowerbouyantdensitiesandweremorehydrophilicthantheless
encapsulatedstrains
Increasedencapsulationwascorrelatedwithincreasedresistanceto
phagocytosis,serumresistanceanddecreasedinductionofPMN
chemiluminiscence
Pgcapsulesconjugatedtobovineserumalbuminandtothefimbriae
proteinhavebeenexaminedasvaccinecandidates
HoltSC,KesavaluL,WalkerS,GencoCA.VirulencefactorsofPorphyromonasgingivalis.Periodontol20001999;28:168-238.

54. OUTER MEMBRANE PROTEINS
Structure–
Complexmultilayeredstructure
Theinner,cytoplasmicmembrane
Athin,peptidoglycan
Assymetrical,outermembrane
-TheoutermembranecontainscomplexLPS,lipoproteinsand
peripheral&transportproteins,Porinproteins,shortfimbriae
-Madeofatleast20proteins
HoltSC,KesavaluL,WalkerS,GencoCA.VirulencefactorsofPorphyromonasgingivalis.Periodontol20001999;28:168-238.

55. OUTER MEMBRANE PROTEINS &
COAGGREGATION
Pgmayplayanimportantroleintheformationandmaintenanceofthe
periodontalbiofilm
ThebenchmarkreportofGibbonsandNygaard(1970)demonstratedthat
therewerespecificinteractionsbwmembersoftheoralmicrobiotaandfor
thefirsttimerevealedthatbacteriadoattachtobothhardandsoftsurfacesas
wellastoeachother.
InPg,thisinteractionwithselectedG+&G-bacteriawasmediatedby
specificoutermembraneproteinsinthewholecell-associatedouter
membraneorintheoutermembranevesicles
HoltSC,KesavaluL,WalkerS,GencoCA.VirulencefactorsofPorphyromonasgingivalis.Periodontol20001999;28:168-238.

56. LIPOPOLYSACCHARIDE
TheoutermembraneofG-bacteriaisassymetric,theouterleafletof
whichcontainstheLPS
Verylargemolecule
3parts–
-TheOantigen
-Coreregion
-LipidA
HoltSC,KesavaluL,WalkerS,GencoCA.VirulencefactorsofPorphyromonasgingivalis.Periodontol20001999;28:168-238.

58. CHEMICALCOMPOSITION
Neutralsugars–Rhamnose,mannose,galactoseandglucose
Glucosamineandgalactosaminerepresenttheaminosugars
Fattyacids
Phosphorus
HoltSC,KesavaluL,WalkerS,GencoCA.VirulencefactorsofPorphyromonasgingivalis.Periodontol20001999;28:168-238.

59. BIOLOGICAL PROPERTIES
EndotoxicactivityisconfinedtolipidA,whiletheimmunologicalactivity
iscontainedwithintheOantigen.
Ogawaetal(1994)demonstratedinductionofIL-1ra,IL-6,IL-8,IFN-
γ,GM-CSFsecretionbyculturedmononuclearcells
Bramatietal(1989)andSismeyDurrant&Hopps(1991)–PGE
2
Tamuraetal(1992)andTakadaetal(1991)–IL-1βandIL-8
ThepreponderenceofevidenceindicatesthatLPS,especiallytheLipidA,
iscapableofstimulatingthehostinflammatoryresponsedirectlyviathe
inductionofhostderivedcytokineproduction
HoltSC,KesavaluL,WalkerS,GencoCA.VirulencefactorsofPorphyromonasgingivalis.Periodontol20001999;28:168-238.

60. Bacterial fimbriae
Thin,straightappendageoriginallyreferredtoasPili
2MAJORCLASSES-
-Type-specificfimbriae
-F-orsexpili
Approx3to25nmindiameter&3to25µmlong
Varyindistribution&numberfrom10to100/cell
HoltSC,KesavaluL,WalkerS,GencoCA.VirulencefactorsofPorphyromonasgingivalis.Periodontol20001999;28:168-238.

61. P GINGIVALIS FIMBRIAE
Peritrichous
Comprisedofatleast1000proteinsubunits(fimbrillinsubunits)
Sexpilinotpresent
Atleast2distinctfimbriaemolecules–
Major
Minor
HoltSC,KesavaluL,WalkerS,GencoCA.VirulencefactorsofPorphyromonasgingivalis.Periodontol20001999;28:168-238.

62. MAJOR FIMBRIAE
Composedoffimbrillin
F/n–
1.Actinbacterialinteractionswithhosttissuebymediatingbacterial
adhesion&colonizationintargetedsites
2.Arecapableofbindingspecificallytoandactivatingvarioushostcells,
resultinginreleaseofcytokines,aswellascelladhesionmolecules
3.Havebeenshowntobenecessaryforbacterialinvasionofhostcells
HoltSC,KesavaluL,WalkerS,GencoCA.VirulencefactorsofPorphyromonasgingivalis.Periodontol20001999;28:168-238.

63. Leeetal(1991)firstreportedthevariationofFimAproteinsand
dividedanumberofPgstrainsinto4typesbasedontheirN-terminal
aasequences.PgfimAgeneshavebeenfurtherclassifiedinto6
variants(typeItoV,andIb)onthebasisofnucleotidesequence
Nakagawa&coworkers(2000)foundamajorityofpatientswere
foundtocarrytypeIIfimAorganisms,followedbytypeIV.In
healthyitwastypeI(2001)
HoltSC,KesavaluL,WalkerS,GencoCA.VirulencefactorsofPorphyromonasgingivalis.Periodontol20001999;28:168-238.

64. MINOR FIMBRIAE
Wasfoundin1996(Hamadaetal)andwasshowntobeshortfimbria-
likeappendagesinanfimAdeficientmutant
mfa1geneencodesforthesubunitproteinoftheminorfimbriae(Mfa
1)
Itisthoughtthatproductionofbothmajor&minorfimbriaeisrequired
fortheexpressionofpathogenictraitsbyPg
-Amanoetal(2004)
HoltSC,KesavaluL,WalkerS,GencoCA.VirulencefactorsofPorphyromonasgingivalis.Periodontol20001999;28:168-238.

65. HEMAGGLUTININS
Pgproducesatleast5hemagglutinatingmolecules
Whenexpressedonthebacterialcellsurface,hemagglutininsmaypromote
colonizationbymediatingbindingofbacteriatoreceptorsonhumancells
SincePgutilizeshemeforgrowth,bindingofbacterialcellstoerythrocytes
mayalsoserveanutritionalfunction
Evidencedoesimplicatearoleforfimbrillin
HoltSC,KesavaluL,WalkerS,GencoCA.VirulencefactorsofPorphyromonasgingivalis.Periodontol20001999;28:168-238.

66. HemaggluttinactivitiesexpressedbyPgincludethosecomplexedwithLPS
onthecellsurfaceandareleasedformdesignatedexohemagglutinin
4hemagglutiningenesfromPgstrainmshavebeenidentified:hagA,hagB,
hagC&hagD
Severalstudieshavedemonstratedthatthehemagglutinationeventsmediated
byPgmightbeduetothecombinedeffectsofatleast3enzymesformedinto
alargeproteincomplex
HoltSC,KesavaluL,WalkerS,GencoCA.VirulencefactorsofPorphyromonasgingivalis.Periodontol20001999;28:168-238.

68. Session 2
contents
Virulencefactors
InvasivenessofPgingivalis
EvidencesupportingaroleforPgingivalisaspathogenin
periodontaldisease
VaccinesforPgingivalis
Conclusion
References

69. PROTEINASES
OneofthepotentiallysignificantvirulencecharacteristicsofPgisthelarge
numberofhydrolytic,proteolyticandlyticenzymesthatareproducedby
essentiallyallknownstrains
Manyoftheenzymesareeither-
Exposedatthesurface(intheoutermembrane)ofthebacteriumwhere
theyareabletocomeincontactwiththehostcellsandtissues
Withintheperiplasmicspacecapableofbeingtransportedtothecell
surface
Intheoutermembranevesicles,whicharesloughedfromtheoutersurface
duringgrowth
HoltSC,KesavaluL,WalkerS,GencoCA.VirulencefactorsofPorphyromonasgingivalis.Periodontol20001999;28:168-238.

70. Serine
Aspartate
Proteinases Thiol
Metalloproteinases
SecretorypatternistypeIV
Ofthese,thecollagenases,aminopeptidasesandtrypsinlike
proteinasesareverticaltoPgPathogenesis.
Trypsinlikeproteinases–theAegandLysproteinasesallcysteine
proteinases,calledgingipanis,thecytokineproteinasesarethiol
proteinasesandcomprisethegroupofendopeptidaseswhose
membersrelyfortheircatalyticactivityonthepresenceofthethiol
groupofcysteineresidueintheenzymesmolecule

72. I. TRYPSIN-LIKE PROTEASE (THE
GINGIPAINS)
Theseproteasesoccurinmultipleformsthatarefoundextracellularlyonthe
bacterialcellsurfaceandinsomecasesareassociatedwithproteinregionsor
“domain”involvedinadherenceproperties.
2proteases-
Arggingipains(Rgp)encodedbyrgpA&rgpB
Lysgingipains(Kgp)encodedbykgp
HoltSC,KesavaluL,WalkerS,GencoCA.VirulencefactorsofPorphyromonasgingivalis.Periodontol20001999;28:168-238.

73. FUNCTIONS OF GINGIPAINS
Adherenceandcolonization:
Gingipainsinhemoglobinbindingandhemeacquisition
Productionofnutritiouspeptides
Degradationofantibacterialpeptides
Exploitingcomplement
Directdegradationofextracellularmatrixproteins
HoltSC,KesavaluL,WalkerS,GencoCA.VirulencefactorsofPorphyromonasgingivalis.Periodontol20001999;28:168-238.

77. II. AMINOPEPTIDASES
Theaminopeptidaseshavebeenfoundinseveralmembersoftheoral
microbiota,manyofwhichexhibitsomearylaminopeptidaseactivity..
Pgisprobablytheonlyperiodontopathicmicrobiotathatexhibits
strongdipeptidylarylaminopeptidaseactivity
Nakamuraetal.(274),defineda“pureenzyme”,furtherstudiesofthis
aminopeptidaserevealedthatitcontainedatleasttwoadditional
aminopeptidases,N-CBz-glycyl-arginylpeptidase(N-CBz-Gly-Gly-
Arg),whichwasbothcellassociatedandextracellular,andan
extracellularpeptidase,glycyl-prolylpeptidase(Gly-Propeptidase).
Bothaminopeptidaseswerethiolandserineactivatedproteinases,
respectively

78. III. Caseinases
Hydrolysetheproteincasein
Existsinatleast3isoformscalledPaseA,B&C
B&Cdisplayacleavagepatternsimilartothatoftrypsin(ie
cleavageofcarboxysideofarginine)
PaseAhasitspreferredcleavagesiteasthecarboxylsideoflysine
ImmunologicalcharacterizationsuggestedthatPase-Cislocatedon
thecellsurfaceandmonoclonalantibodiesagainsttheprotein
inhibitedthehemagglutinatingactivity,hydrolyzedBApNAand
stronglydegradednativetypeIcollagen
HoltSC,KesavaluL,WalkerS,GencoCA.VirulencefactorsofPorphyromonasgingivalis.Periodontol20001999;28:168-238.

79. IV. COLLAGENASE
Collagenhasbeenfoundtocompriseasignificantpercentageof
gingivalconnectivetissues.Themajorportionofthegingival
connectivetissueisthehighlyorganizedcollagenfibers,whichhave
astheirprimaryfunctionthemaintenanceoftissueintegrityand
function.
Itwasalmost35yearsagothatShultz-Haudt&Schrep(1955)
demonstratedthatamixedcultureofbacteriaisolatedfromthe
gingivalcavitydisplayedcollagenolyticactivity.Thisactivitywas
demonstratedtobecollagenasefromBacteroidesmelanogenicus.
HoltSC,KesavaluL,WalkerS,GencoCA.VirulencefactorsofPorphyromonasgingivalis.Periodontol20001999;28:168-238.

80. Datasupporttheparticipationofbacteriallyderivedcollagenase;
howeverthesedataareequivocal.
CollagenaseisperhapsthemostimportantofthePgingivulis
proteolyticenzymes,andifexpressedinvivo,wouldbeamajor
destructiveenzyme(virulencefactor)associatedwiththesofttissue
destructioncharacteristicofhumanperiodontitis.
SeveralinvestigatorshavepostulatedthatthePgingivulis
collagenasemayparticipatewithhost-derivedcollagenaseinthe
destructionofgingivalcollagen
HoltSC,KesavaluL,WalkerS,GencoCA.VirulencefactorsofPorphyromonasgingivalis.Periodontol20001999;28:168-238.

81. OTHER ENZYMES
Alkalinephosphatase
Superoxidedismutase
Sulfatase,heparinaseandchondroitinase
HoltSC,KesavaluL,WalkerS,GencoCA.VirulencefactorsofPorphyromonasgingivalis.Periodontol20001999;28:168-238.

82. EVIDENCE SUPPORTING A ROLE FOR P. GINGIVALIS AS PATHOGEN IN
PERIODONTAL DISEASE
Criterion
Association
Elimination
Hostresponse
Increasedinperiodontitislesions,found
associatedwithcrevicularepithelium
Suppressedoreliminatedinsuccessful
therapy,foundinrecurrentlesions.
Increasedsystemicandlocalantibody
levelsinLAP

83. Criterion
Animalstudies
Virulencefactors
Foundtobeimportantinexperimental
mixedinfectionsandinperiodontitisin
thecynomolgusmonkey
Hosttissuescelladherenceandinvasion,
collagenase,trypsinlikeenzyme
(gingipains),fibrinolysin,Phospholipase
A,phosphates,endotoxin(LPS),factors
thataffectPMNfunction

84. INVASIVENESSOFPGINGIVALIS
Aspartofitsstrategiesforsurvivalintothehost,P.gingivalisisable
toinvadecellsandtissues(Yilmaz,2008),thusavoidingtheimmune
surveillance.
Porphyromonasgingivaliscanactivelyinvadegingivalepithelial
cells,whereitcanmaintainviabilityandreplicate(Beltonetal.,
1999;Tribbleetal.,2006).
Thisinvasivepropertyisdependentonitsmajorfimbriae,which
bindtob1integrinonthesurfaceofhostcells,aneventthatcauses
rearrangementsoftheactincytoskeletontoallowinternalization
(Yilmazetal.,2002,2003)
GriffenAL,BeckerMR,LyonsSR,MoeschbergerML,LeysEL.Prevalenceofporphyromonasgingivalisandperiodontalhealthstatus.JClinMicrobiol1998;36:3239-
42.

85. Porphyromonasgingivaliscanalsoinvademacrophages,butwithin
thesecellsitsreplicationislessactive(Wangetal.,2007).
onceP.gingivalishasinvadedintracellularly,therearenosignsof
apoptosisornecrosis(Nakhjirietal.,2001).Itcanthenactively
secreteanATP-hydrolysingenzyme,thussuppressingATPdependent
apoptosis(Yilmazetal.,2008)andallowingitssurvivalinhostcells.
Subsequently,itcandisseminatefromcelltocell,throughactin
cytoskeletonbridgeswithoutcausingcelldeath,andspreadwhile
avoidingimmunesurveillance(Yilmazetal.,2006).
GriffenAL,BeckerMR,LyonsSR,MoeschbergerML,LeysEL.Prevalenceofporphyromonasgingivalisandperiodontalhealthstatus.JClinMicrobiol1998;36:3239-
42.

86. OnceP.gingivalisisestablishedinthecell,itaffectscell-cycle
pathwaysandthusacceleratesproliferationofgingivalepithelial
cells,inafimbriae-dependentfashion(Kuboniwaetal.,2008).This
couldwellconstituteamechanismofexpansionoftheperiodontal
pocketepithelium,whichisahistopathologicalfeatureof
periodontitis.
GriffenAL,BeckerMR,LyonsSR,MoeschbergerML,LeysEL.Prevalenceofporphyromonasgingivalisandperiodontalhealthstatus.JClinMicrobiol1998;36:3239-
42.

87. Relevance of cell invasion
RegulationofMMPproductionbyGECisdisruptedandthiswill
interferewithextracellularmatrixrepairandreorganization
InvasivePgcellsinhibitsecretionofIL-8byGEC
GriffenAL,BeckerMR,LyonsSR,MoeschbergerML,LeysEL.Prevalenceofporphyromonasgingivalisandperiodontalhealthstatus.JClinMicrobiol1998;36:3239-
42.

88. Treatment of periodontal infections
3factorsplayamajorroleinthedifficultiesencounteredinachieving
long-termcontrolofperiodontalinfectionswithouttheneedfor
continuousmaintenance-
a)Thefirstisthenumerousreservoirsofthesetaxaintheoralcavity
coupledwiththepotentialforreacquiringthetaxafromotherpersonsin
theenvironment
b)Thesecondisthestabilityconferredoncommunitiesofspecieswhile
livinginbiofilms
c)Thethirdistheresiliencyofthe“climaxcommunity”
GriffenAL,BeckerMR,LyonsSR,MoeschbergerML,LeysEL.Prevalenceofporphyromonasgingivalisandperiodontalhealthstatus.JClinMicrobiol1998;36:3239-
42.

89. Future directions in the treatment of P gingivalis
Useofisolatedadhesinsasadhesinsisoneapproach
Expression&secretionontheoralcomensalS.gordoniiofPgfimbrillin
domains
ExpressionofHagBinliveavirulentSalmonellatyphimuriuminduces
primaryandrecallantibodyresponseinbothserumandsalivaandmay
thusprovideaneffectivemeansofdeliveringvaccinescapableof
blockingcolonization
GriffenAL,BeckerMR,LyonsSR,MoeschbergerML,LeysEL.Prevalenceofporphyromonasgingivalisandperiodontalhealthstatus.JClinMicrobiol1998;36:3239-
42.

90. Asanalternativetovaccinedelivery,blockingagentstargetedtoactive
domainsofadhesinsorproteases
Otherpotentialtargetsincludemoleculesinvolvedintheregulationof
virulencegeneexpression,virulencefactorsupregulatedinvivoand
signalingmoleculesinvolvedinbiofilmexpression.TheavailabilityofPg
genomecanbeanticipatedtomaketheseapproachesmoreviable
GriffenAL,BeckerMR,LyonsSR,MoeschbergerML,LeysEL.Prevalenceofporphyromonasgingivalisandperiodontalhealthstatus.JClinMicrobiol1998;36:3239-
42.

91. Vaccines for P gingivalis
Vaccinationisaprocessthatinducesspecificimmuneresistancetoa
bacterialorviralinfection.
AcommonfindinginpatientswithperiodontitisisthepresenceofP.
gingivalisspecificantibodiesinserumandgingivalcrevicularfluid.
ImmunizationwithseveralP.gingivalis-specificantigenshasbeen
showntoenhancetheimmuneresponseagainstP.gingivalis,as
demonstratedbytheinductionofspecificantibodiesandreductionof
P.gingivalis-inducedalveolarbonelossinanimalmodels.
NitinK,NitinD,andSwapnaM.Periodontalvaccine:Adreamorreality.JIndianSocPeriodontol.2011;15(2):115–120.

92. Theproductionofantibodiesgenerallyindicatestheactivationofour
majorhostdefensemechanism;theseantibodiesareinsufficientto
clearP.gingivalisinfection.Althoughcompleteprotectionthrough
immunizationhasnotyetbeenachieved,newknowledgeabout
specificP.gingivalisantigensholdspromisingpossibilitiesforthe
future
NitinK,NitinD,andSwapnaM.Periodontalvaccine:Adreamorreality.JIndianSocPeriodontol.2011;15(2):115–120.

93. Activeimmunization
•Wholebacterialcells
•SubunitVaccines
•Syntheticpeptidesasantigens
Passiveimmunization
•Murinemonoclonalantibody
•Plantibodies
Geneticimmunization
•Plasmidvaccines
•Live,viralvectorvaccines
NitinK,NitinD,andSwapnaM.Periodontalvaccine:Adreamorreality.JIndianSocPeriodontol.2011;15(2):115–120.

94. BruceC.Ross&coworkers(2001)usedawholegenomesequencing
approachtoidentifypotentialvaccinecandidates.Fromagenomicsequence,
120geneswereselectedTheselectedgeneswereclonedforexpressionin
EscherichiacoliandscreenedwithP.gingivalisantiserabeforepurification
andtestinginananimalmodel.Twooftheserecombinantproteins(PG32
andPG33)demonstratedsignificantprotectionintheanimalmodel,whilea
numberwerereactivewithvariousantisera.Thisprocessallowstherapid
identificationofvaccinecandidatesfromgenomicdata.
NitinK,NitinD,andSwapnaM.Periodontalvaccine:Adreamorreality.JIndianSocPeriodontol.2011;15(2):115–120.

95. FrankA.Roberts&coworkers(2004)measuredPGE
2levelsingingival
crevicularfluidofprimatesimmunizedwithaP.gingivalisvaccine
(formalin-killedP.gingivalis)followedbyligature-induced
periodontitis.PGE
2levelsweredramaticallysuppressedinimmunized
animalsversuscontrols.Asignificantcorrelationwasalsofoundbetween
PGE
2levelsanddecreasedbonelossscores.Thisstudypresentsthefirst
evidenceofapotentialmechanisminvolvedinperiodontitisvaccine-induced
suppressionofbonelossinanonhumanprimatemodelandoffersinsightinto
theroleofPGE2inperiodontaldestruction.
NitinK,NitinD,andSwapnaM.Periodontalvaccine:Adreamorreality.JIndianSocPeriodontol.2011;15(2):115–120.

96. Agenta’sPatentTechnology(filed12/6/2003)“Immunizationagainst
periodontitiswiththeHA2hemoglobinbindingdomainof
Porphyromonasgingivalis”
HowdoweknowHA2domainisimportanttoP.gingivalis?
HA2domainacquiresironandporphyrin
Thispathogenhasnobiologicalmachinerytomaketheporphyrin
metabolite
ThepathogengrowspoorlyifHA2isdeleted
AgentahastestedanHA2domainvaccineinananimalperiodontitismodel
NitinK,NitinD,andSwapnaM.Periodontalvaccine:Adreamorreality.JIndianSocPeriodontol.2011;15(2):115–120.

97. CONCLUSION
ItisevidentthatP.gingivalishasdevelopedmechanismstoinvadeand
persistintothehost,byabsolutelyadaptingtoitslocalniche.Its
paradoxicallyopposing(stimulatoryvs.inhibiting)effectsoninnate
immuneandinflammatoryresponsesaimtosubverthostdefence
mechanisms,inordertofacilitateitssurvivalinthetissues
Finally,asperiodontitisisofpolymicrobialnature,itisreasonableto
considertheroleofdifferentbacterialspecieswithinthecontextof
(subgingival)biofilmcommunities.Hence,P.gingivalisislikelyto
functioninconcertedactionwithotherspecies,totheirmutualbenefit.

98. REFERENCES
SocranskySS,HaffajeeAD.Dentalbiofilms:Difficulttherapeutictargets.
Periodontol2000.2002;28:12-55.
GriffenAL,BeckerMR,LyonsSR,MoeschbergerML,LeysEL.
Prevalenceofporphyromonasgingivalisandperiodontalhealthstatus.JClin
Microbiol1998;36:3239-42.
HoltSC,KesavaluL,WalkerS,GencoCA.Virulencefactorsof
Porphyromonasgingivalis.Periodontol20001999;28:168-238.
NitinK,NitinD,andSwapnaM.Periodontalvaccine:Adreamorreality.J
IndianSocPeriodontol.2011;15(2):115–120.

99. HowKHetal.Lifebelowthegumline:PathogenicmechanismsofPg.
MicrobiologyandMolecularBiologyReviews,December1998,1244-
1263.
ChenT,NakayamaK,BelliveauL&DuncanMJ.Porphyromonas
gingivalisgingipainsandadhesiontoepithelialcells.InfectImmun.2001;
69:3048–3056.
Bao,K.etal.RoleofPorphyromonasgingivalisgingipainsin
multispeciesbiofilmformation.BMCMicrobiol.2014;14:258-260.
VanWinkelhoff,A.J.,&Boutaga,K.Transmissionofperiodontal
bacteriaandmodelsofinfection.JournalofClinicalPeriodontology.
2005;32(s6),16–27.