salmonella 2015 - bsc blackboard

7/25/2019 Salmonella 2015 - Bsc Blackboard

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Biology of Salmonella

Dr Sophie Helaine


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Human diseases

Typhoid (S. entericaTyphi and S. Paratyphi):17 million casesand 600,000 deaths/yr - increasing multiple drug resistance recurrence infection

on-typhoidal (e!g S. entericaTyphimurium)" 1!# $illioncases and # million deaths/yr (ma%or pro$lem in su$-&arahan'frica)

Salmonellapathogenesis


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SalmonellaTyphi andhuman typhoid

Typhoid prevalence, 2006


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Transmission (faecal-oral)

SalmonellaTyphi andhuman typhoid

Chronic carrier stateTyphoid Mary


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S.Typhi S.Typhimurium

h (10 days)

T0

1* days


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Human diseases

Typhoid (S. entericaTyphi and S. Paratyphi):17 million cases

and 600,000 deaths/yr - increasing multiple drug resistance recurrence infection

on-typhoidal (e!g S. entericaTyphimurium)" 1!# $illioncases and # million deaths/yr (ma%or pro$lem in su$-&arahan

'frica)



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S.Typhimurium in+asion of cells

olonisation of Peyer.s

Patches, mesenteric lymphnodes

atal $acteraemiantracellular replication in spleen and li+e

macrophages (up to 10 $acterial cells/org

implies 2#0 rounds of cell di+ision)

Murine model of Typhoidfever


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3stimates suggest appro4! of S.Typhimuriumgenome

5uired for +irulenceS.Typhimurium has 600 s 82 appro4! +irulence gen

ppro4! genes identi9ed to dateost are present on Pathogenicity slands/islets (2 60)

:ut, $iochemical and physiological functions of manyemain un;no


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!i"erent virulence genes act atdi"erent stages of S. Typhimurium

virulencestage of environmental response virulenceinfection stimulus genes

stomach low pH acid tolerance fur, atr

small osmotic stress motilityintestine anaerobiosis adhesion flg, lpf and pef

epithelium anaerobiosis invasion many (e.g.inv/spa)penetration cell contact

blood- complement serum resistance rfb, rfc, rckstream antimicrobial peptide resistance sap, htr

peptides

macrophage low pH, low Mg comple! many(pag, "#$-%, spv)


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Salmonella-containing vacuoles in spleen cells

Salmonellaan intracellularpathogen


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isteriahigella

SalmonellaMycobacteria

Coxiella

Salmonellaan intracellularpathogen


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#ntracellular replication in macrophages($6 h)

%ild-type

Dhar and McKinney, Current Opinion in Microbiology 2007


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pDiGi

pDiGc

Helaine et al, PNAS 200

Measuring replication y &luorescence!ilution


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Helaine et al, PNAS 200

!one"#arro$ deri%ed#acrophage&

' h

Non"replicating bacteria ( )0 *

Measuring replication y &luorescence!ilution


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Many bacterial species form persisters - highly tolerant to antibiotics

Persistent bacterial infections pose significant public-health problems

Typhoid fever in humans - 1! of treated patients suffer a relapse

" ma#or brea$through %as the discovery that E. coli in vitro persisters are non-

replicating bacterial cells &Balaban et al' Science ())*+

'acterial persisters


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Per&i&ter& are tran&iently tolerant to A! treat#ent

+nteraction $ith ho&t M=, e%en tran&ient, enhance& the or#ation oper&i&ter cell& o Salmonella to- dierent cla&&e& o A!

Survival of Salmonella to AB treatment

Salmonellapersisters induced y contact%ith host M


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. *

2 *

Antibiotic tolerant bacteria / non"ly&ed by epo&ure to beta"lacta#

Ho&t induced per&i&ter& are non"replicatingbacteria

total intracellular

population

)

()

*)

,)

)

1))

!

ofMa.

1))

1)1

1)(

1)/

1)*

0P

total intracellular

population

intracellular

persisters

)

()

*)

,)

)

1))

!

ofMa.

1))

1)1

1)(

1)/

1)*

0P

luorescence

Host induced Salmonellapersisters arenon-replicating


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21 hin #acrophage&

ceotai#e 200 g3#4

arabino&e

gfp dsRed

+P56"inducible arabino&e"inducible

Proportion o the non"replicatingbacteria re&u#e gro$th

1))

1)1

1)(

1)/

1)*

31-H

1)

)

1)1

1)(

1)/

1)*

13(-H

8e&pon&i%e non"replicating bacteriaater 21 h in #acrophage&

0P

Ds2ed

1))

1)1

1)(

1)/

1)*

31-H

1)

)

1)1

1)(

1)/

1)*

13(-

H

8egro$ing non"replicating bacteriaater 21 h in #acrophage&

Ds2ed

0P

responding

regro%ing

on-replicating acteria*egro%th


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21 hin #acrophage&

ceotai#e 200 g3#4

arabino&e

Non replicating bacteria9 re&er%oir or relap&e o inection

1))

1)1

1)(

1)/

1)*

1))

1)1

1)(

1)/

1)*

1))

1)1

1)(

1)/

1)*

1))

1)1

1)(

1)/

1)*

Ds2ed

8e&pon&i%e per&i&ter& a,ter 21 h in +:Nacti%ated C)7 #acrophage&

8e&pon&i%e and regro$ing per&i&ter& inC)7 #acrophage&

Ds2ed

0P 0P

on-replicating acteria*egro%th


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Bacterial actors 4 Host signals 4

Heterogeneity of intracellular population


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Human diseases

Typhoid (S. entericaTyphi and S. Paratyphi):17 million cases

and 600,000 deaths/yr - increasing multiple drug resistance recurrence infection

on-typhoidal (e!g S. entericaTyphimurium)" 1!# $illioncases and # million deaths/yr (ma%or pro$lem in su$-&arahan

'frica)


Salmonella an intracellular


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+#-$mediates in+asion of host cells

andintestinal secretory and in?ammatoryresponses

+#-2is re5uired for $acterial replicationand immune modulation

Salmonellaan intracellularpathogenT%o T++



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Adhesion Invasion SCV formation SCV maturation Replication

SP5-1 T/SS SP5-( T/SS

6.tracellular 5ntracellular



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e@ectors induce actin polymerisation,

mem$rane ruAing and $acterial internalisation

Salmonellainvasion of epithelialcells occurs

via the +#-$ type ### secretion

system

3@ector



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Adhesion Invasion SCV formation SCV maturation Replication

SP5-1 T/SS SP5-( T/SS

6.tracellular 5ntracellular



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effectors &Sif"' Sse7' Sse0' etc+

translocon pore &Sse8' SseD+

translocon &SseB+

vacuolar membrane

bacterial outermembrane

bacterial innermembrane

Ssa9

Ssa8

secreton needle

Ssa7

H:

H:

H:

H:

H: H:

H:

SsaM

Spi8

Ssa3

cidic pH triggerssecretion

ssaVmutantis null for+#-2 function

+#-2 Type ###

cretion system


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#ntracellular replication defect of a +#-2null mutant in macrophages ($6 h)

%ild-type +#-2 mutant


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."ectors of the +#-2 T++

rom igueira and Holden' Microbiology' ()1(


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rom igueira and Holden' Microbiology' ()1(


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:igueira et al, #anu&cript in preparation


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Human diseases

Typhoid (S. entericaTyphi and S. Paratyphi):17 million casesand 600,000 deaths/yr - increasing multiple drug resistance recurrence infection

on-typhoidal (e!g S. entericaTyphimurium)" 1!# $illioncases and # million deaths/yr (ma%or pro$lem in su$-&arahan'frica)



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yphoidal Salmonella in H#/-infected frican

T& (S.Typhimurium and 3nteritidis)"

Predominantly cause self-limiting gastroenteritis:BTma%or cause of in+asi+e disease in 'frica, young

children and CD-infected adults

on speci9c fe+er (E/- diarrhea) :acteremiaase fatalities (**-> F)': resistanceo +accine


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&2eddy 6"' et al; Lancet Infect Dis ()1)+

Salmonellaeare the commonest causeof acterial loodstream infection in

frica


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;oro, et al. ature Genetics, *01*


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Cost resistance to Salmonellarelies on"

- cell-mediated immunity (macrophages, Ps, Hcells)

- complement ;illing (induced $y 'nti$odies Ps)

CD-uninfected sera CD-infected sera

34posure to serum (min)Iog10changeinSalmone

lla(cfu/ml)

Iac; of '$J

acIenan, et al. &cience, *010


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CD-uninfected sera CD-infected sera

Total anti- &almonella gG titerIog

10changein

Salmonella(cfu/ml)

acIenan, et al. &cience, *010


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nhi$itory factor" IP& gG


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Ki+erting complement deposition a


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Salmonella enterica di@erent diseases, typhoid and non-typhoidal

eplicates in macrophages in mem$rane-$ound +acuoles

Persists chronic infection, carriers/shedders

&P-1 and &P-* Type secretion systems are important

+irulence components" &P-1 for in+asion and &P-* forreplication

+ummary


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