Download pneumo-virulence - Institut Maurice Rapin

Streptococcus pneumoniae
Facteurs de virulence
Pierre MOINE
CHU de Bicêtre
Host-pathogen interactions: Redefining the basic
Concepts of virulence and pathogenicity
[Cassadeval & Pirofski, Infect Immun 1999]
Virulence
« The relative capacity of a microbe to cause damage
In host »
Virulence factor
« A component of a pathogen that damages the host »
Large scale identification of virulence genes
from Streptococcus pneumoniae
[Polissi A, Infect Immun 1998]
• 126 Virulence genes
• Class I "known virulence factors": LytA, IgA1
protease, NanA, Hyl, Cbp
• Class II "métabolic pathways": purine biosynthesis,
phosphate assimilation, synthesis of glutamine,
anaerobic metabolism
• Class III "ATP dependent proteases"
• Class IV "ABC transporters"
• Class V "DNA recombination/repair"
• Class VI "unknown functions": n = 63
Large scale identification of virulence genes
from Streptococcus pneumoniae
[Polissi A, Infect Immun 1998]
• Processus multifactoriel
• Adaptation bactérienne à l'environnement hôte
(infection, croissance, survie)
• Gènes identifiés chez S pneumoniae déjà
identifiés chez d'autres pathogènes (V cholerae,
S typhimurium, S aureus, P aeruginosa)
• Spécificité de site: modèle de pneumonie (LytA,
Hyl, NanA) vs modèle de septicémie (ip)
Ply
LytA
PspA
NanA
Hyl
CbpA
i.p. challenge 5 x 103 cfu
pneumolysin
autolysin
surface protein
neuraminidase
hyaluronidase
surface protein
Berry AM, Infect Immun 2000
Ply
pneumolysin
LytA autolysin
PspA surface protein
NanA neuraminidase
Hyl
hyaluronidase
CbpA surface protein
i.p. challenge 8 x 106 cfu
Berry AM, Infect Immun 2000
Ply
LytA
PspA
NanA
Hyl
CbpA
pneumolysin
autolysin
surface protein
neuraminidase
hyaluronidase
surface protein
i.p. challenge 105 cfu
Berry AM, Infect Immun 2000
Differences in virulence for mice among S pneumoniae
strains of capsular types 2, 3, 4, 5, and 6 are not attributable
to differences in pneumolysin production
Capsular
Type
2
3
3
3
4
4
4
6A
6A
6B
6B
Strains
DL100
D39
WU2
A66.1
EF10197
EF3296
L81905
BG9739
DBL6A
EF6796
BG9163
BG7322
Mean survival
time (days)
1.1
0.9
1.1
1.2
3.5
2.3
2.4
6.7
5.3
6.8
5.7
Cytoplasmic hemolytic
pneumolysin titers
8800
1900
1600
3100
4900
4900
7000
2820
2300
3900
2300
[Benton, Infect Immun 1997]
Relationship between
virulence in mice and
susceptibility
to penicillin for 122 clinical
S. pneumoniae strains of
various serotypes.
[Azoulay Dupuis, AAC 2000]
Relationship between virulence in mice
and susceptibility to penicillin within
3 groups of S pneumoniae serotypes
[Azoulay-Dupuis, AAC 2000]
Serotypes
V+S V+R V-S
1, 3, 4 (n=16)
83%
-
17%
6 (n=32)
34%
-
38% 12% 16%
-
-
44% 24% 32%
9, 14, 19, 23 (n=50)
V-I
V-R
-
-
V+ virulent; V- avirulent; S penicillin susceptible;
I intermediate or R resistant
Complex Relationship between acquisition of
b-lactam resistance and loss of virulence in
Streptococcus pneumoniae
[Rieux et al., JID 2001]
Strain
Construction
Penicillin
LD50
MIC (mg/l) log10cfu/mouse
15986
DNA donor
8
6.8±0.1
23477
Recipient
0.03
2.0±0.6
23.2b
23477x pbp2b allele
0.06
5.7±1.0
23.2x
23477x pbpX allele
0.06
4.4±0.2
23.2b.2x 23.2bx pbp X allele
0.125
6.0±0.6
After 1 i.p. passage in mice
23.2b
23.2x
23.2b.2x
1.9±0.2
4.1±0.6
1.9±0.1
Variants pneumococciques
Transparent
Autolyse
+
Colonisation nasopharyngée
++
Adhérence récepteurs glycoconjugués
Cel nasopharyngées GlcNAcb1-3Gal
++
Cel pulmonaires repos GlcNAcb1-3Gal
+
Cel pulmonaires repos GlcNAcb1-4Gal
+
Cel pulmonaires activées GlcNAc
++
Adhérence aux PAF récepteurs
++
Adhérence cellulaire
Pulmonaires repos
+
Pulmonaires activées
+
Endothéliales repos
+
Endothéliales activées
++
Virulence Infection ip
0
Opsonisation-phagocytose
++
Ac téichoique/polysaccharide capsulaire
+++ / +
Opaque
0
0
0
+
+
0
0
+
0
+
0
++
±
+ / +++
Variants pneumococciques
Transparent
Opaque
+
+
+++
+
+
+++
CbpA (protéine de surface)
+++
+
SpxB Pyruvate oxydase (H2O2)
+++
+
+
+++
+++
+
Ply (pneumolysine)
LytA (autolysine CBP)
PsPA (protéine de surface CBP)
EF-Ts
PpmA (« proteinase maturation protein »)
[Weiser, Infect Immun 1996; Rosenow, Mol Microbiol 1997;
Kim, J Infect Dis 1998; Overweg, Infect Immun 2000]
Role of TNFa in pathogenesis of
pneumococcal pneumoniae in mice
[Takashima et al. Infect Immun 1997]
120
Survival rate (%)
100
Control
80
60
40
anti-TNFa antibody
20
0
0
2
6
8
10
12
Time after infection (day)
14
Role of TNF-a in the host response of mice bacteremia
caused by pneumolysin-deficient S. pneumoniae
[Benton, Infect Immun 1998]
Log TNF-a pg/ml
Log CFU/ml blood
10
5
4
8
3
2
6
1
4
0
0
10
D 39
20 30 40
Time (hr)
50
D 39 + anti-TNF-a
0
PLN
10
20 30 40
Time (hr)
50
PLN + anti-TNF-a
Targeted disruption of the p50 subunit of NF-kB leads to
multifocal defects in immune responses
[Sha et al., 1995]
Increased susceptibility to S. pneumoniae
Infected mice/control uninfected mice
NF-kB ratio
8
7
6
5
4
3
2
1
P4241
Mix "P4241"
R6
P15986
1
i.t. challenge 105 cfu
of S. pneumoniae per
mouse
4 6
24
Time after infection (hrs)
Amory-Rivier et al, CCM 2000
TNF-a pg/ml
1250
P4241
R6
P15986
1000
750
500
250
0
2
4 6
12
Time after infection (hrs)
24
Amory-Rivier et al, CCM 2000
Lung TNF-a
12500
10000
P30606: 107 cfu/mouse
7500
P23477: 107 cfu/mouse
P26772: 107 cfu/mouse
5000
P15986: 107 cfu/mouse
2500
P4241: 105 cfu/mouse
0
0 2 4 6 12
24
48
Time post infection (hrs)
Conclusion
- Virulence et facteurs de virulence du germe
Processus multifactoriel
Variations intra-souches
Site dépendant
« Effet inoculum »
Effets additifs synergiques
Résistance à la pénicilline
Multiples inconnus
- Hôte: polymorphisme génétique humain
S. pneumoniae TIGR4
genome
R6
D39
Comparative
genome hybridizations
Science 2001