Transcript Genomic Analysis of Meningococcal serogroup W isolates

Xin Wang, Ph.D
Meningitis Laboratory
CDC
1
2



Human commensal bacterium and also one of the
common pathogens causing bacterial meningitis.
12 serogroups based on the structure and chemical
composition of cell surface associated capsular
polysaccharide.
Only six serogroups (A, B, C, W, X, and Y) are
associated with most invasive disease.
3

Frequent horizontal gene transfer events and vaccineinduced immune selection

Antigenically and genetically diverse

Dynamic population structure

Common typing methods to determine
genetic/antigentic variations
 Multilocus sequence typing (MLST)
 Typing of outer membrane protein (OMP) encoding genes (porA, fetA,
fHbp, nadA, and nhbA)
 Pulse-Field Gel Electrophoresis (PFGE)
4
 Targets the internal region (400500 bps) of the 7 house-keeping
genes/loci
 For each locus, an allele number
is assigned to each unique
nucleotide sequence.
 A sequence type (ST) is defined by
the allelic profile of the seven loci.
 Strains that have at least four
alleles in common are usually
defined as the same clonal
complex (CC).
abcZ
4
adk
10
aroE
5
fumC
4
gdh
6
Maiden, M., et al. 1998. PNAS
pdhC
3
pgm
8
ST
32
CC
CC32/ET-5 complex
5
PorA (for porin A)
•Class 1 transmembrane protein with 8 loops
•Major component of OMV-based vaccines
•Two hypervariable regions, VR1 (loop 1) and VR2 (loop 4).
•Nomenclature: P1.5-2,16-2
•VR1 & VR2 are targeted by the bactericidal antibodies and
are thus under selective pressure.
FetA (ferric enterobactin transport)
•Formerly FrpB (iron-repressed protein B)
•13 surface-exposed loops
•One variable region: F3-3
B vaccine immunogens
•FHbp, NadA and NhbA
6
Strain genotypes with significant changes
between 2000-05 and 2006-10, ABCs
Serogroup
Clonal
Complex
PorA:FetA
2000-05
No. of
isolates
B
CC41/44
CC32
P1.7-2,4:F1-5
P1.7,16-2:F3-3
P1.7,16:F3-3
CC103
CC11
P1.5-1,10-4:F3-9
P1.22-1,14:F3-6
C
P1.5,2:F1-30
P1.5,2:F3-6
P1.5,2:F4-12
P1.5-1,10-4:F3-6
P1.5-1,10-62:F3-6
Y
CC23
P1.5-1,2-2:F5-8
P1.5-2,10-1:F4-1
CC32
P1.7,16:F3-3
NG
n=298
17
9
49
n=277
17
23
32
57
3
25
0
n=319
97
167
n=29
8.0
2006-10
Proport
ion1
5.8
3.1
16.6
6.1
8.3
11.6
20.6
1.1
9.0
0
30.4
52.4
27.6
No. of
isolates
n=127
2
0
16
n=162
28
3
1
18
28
2
21
n=196
95
63
n=19
0
p value
Propor
tion1
1.4
0.0
12.7
0.02
0.02
0.055
17.3
1.9
0.0002
0.009
0.6
11.1
17.3
1.2
13.0
<0.0001
0.03
<0.0001
0.002
<0.0001
48.5
32.1
<0.0001
0.004
0.0
0.03
(Wang et al unpublished)
7
Meningococcal disease
 Significant public health concern due to its high
mortality rate world-wide.
 Meningococcal meningitis epidemics were reported
in many other countries in North America, Asia,
Europe and South America.
 Shift in the global epidemiology of meningococcal
disease in post-vaccine era
8
Meningitis epidemics in the meningitis belt
 highest incidence (up to 1000 per 100, 000
population) found in the belt
 occur in cycles of 8-10 years
 predominately caused by serogroup A preMenAfriVac
http://wwwnc.cdc.gov/travel/yellowbook/2012/
9
Eradication of serogroup A meningitis
epidemics
 MenAfriVac, an affordable serogroup A conjugate vaccine
developed for African countries
 Introduction in Burkina Faso, Mali and Niger in 2010
 No serogroup A detected among vaccinated population
http://www.meningitis.org/assets/x/53978
http://www.thegatesnotes.com/Topics/Health/The-
Post-MenAfriVac



Followed the implementation of MenAfriVac,
serogroup W becomes the most prevalent strain
causing meningococcal disease in vaccinated
countries.
There is an increase in serogroup W disease in the
vaccinated countries such as Burkina Faso and Mali.
This is extremely concerning because serogroup W
strains currently circulating in Africa may have the
potential to cause epidemics and large outbreaks.
11
12




The first large NmW outbreak occurred during the Hajj
pilgrimage in Saudi Arabia in 2000
More than 300 cases were reported
Caused by a strain of CC11 with a PorA type of P1.5,2,
PFGE pattern 40, and 16S type 31
This strain is known as the Hajj clone
13



Intercontinental spread of serogroup W (the Hajj clone)
since Hajj outbreak: European, Asian, Middle East, North
African countries and the United States.
A large outbreak involving nine European countries (the
UK, France, the Netherlands, Germany, Finland, Sweden,
Belgium, Switzerland, and Norway) was reported
immediately following the Hajj outbreak in 2000.
A phylogenetic analysis indicated the Hajj outbreak and
associated strains collected from Saudi Arabia, France,
Singapore, Finland and the United States in 2000 had
identical PFGE pattern (40), 16S type (31) and PorA type
(P1.5,2), and belonged to the CC11 (ST-11)/ET-37
complex (ET-27).
14

NmW strains from 1970-2000 that were not
epidemiologically linked to the Hajj outbreak
• Diverse genetic background
• Some strains were genetically identical to the Hajj clone by
PFGE, MLEE and PorA typing; 16S type differs by 3 nucleotides

The Hajj-related clone circulating in different regions
before 2000;

Due to the recombining nature of N. meningitidis,
genetic variation occurred during the transmission

The Hajj outbreak led to the global transmission of
this clone.
15
Accounts for <5% of invasive meningococcal disease in the
United States
No. of
Isolates
Clonal Complex
Total
CC22
CC11
CC23
CC174
CC167
CC168
unassigned
95
57
5
7
3
1
1
21
14 W cases in South FL, 2008-9 (6 cases during 2004-7)
CC11/ST11, and similar to the Hajj clone by PFGE
(Wang et al unpublished)
16





CC11/ET-37 complex has been present in Africa
since at least 1993
In 2002, a serogroup W epidemic was reported in
Burkina Faso, which affected 12,000 people and
caused 1400 deaths.
Caused by a CC11 strain, showing similarity to the
Hajj clone
This clonal complex continues to spread in African
countries after the 2002 Burkina Faso epidemic and
remains to be the prevalent genotype.
Clonal complex 175 emerged between 2002 and
2010.
17
NmW strains in the meningitis belt between 2004
and 2010, Pre-MenAfriVac
Clonal Complex
No. (%) isolates
CC11
66
CC23
1
CC175
38
Caugant DA, Kristiansen PA, Wang X, Mayer LW, et al. (2012) PLoS ONE 7(9): e46019.doi:10.1371/journal.pone.0046019
18
19



To determine the genetic similarity and
difference of NmW strains from different
geographic locations, and the genetic
relatedness of these strains to the Hajj clone
To identify genetic markers associated with
epidemics and outbreaks.
To determine whether capsule switching has
occurred between serogroups W and C.
20
Lab_Id
M22702
M23413
M22803
M25087
M07293
M23347
M09261
M09293
M24695
M22811
Year
1998
2011
2005
2012
2000?
2011
2002
2002
2010
2006
Country
Algeria
Burkina Faso
Chad
Mali
South Africa
United States
Burkina Faso
Burkina Faso
Burkina Faso
Niger
submission type
endemic
endemic
endemic
endemic
endemic
FL outbreak
epidemic
epidemic
epidemic
epidemic
SG
W
W
W
W
W
W
W
W
X
W
ST
8814
11
11
11
CC11/ET-37
CC11/ET-37
CC11/ET-37
11
CC11/ET-37
181
2881
M22831
M07149
M22822
2009
2000
2007
Niger
Saudi Arabia
Togo
epidemic
epidemic
epidemic
A
W
W
2859
11
2881
CC181
CC175
CC5/subgroup
III
CC11/ET-37
CC175
M25419
M22819
M22740
2005
2007
2001
South Africa
Benin
Cameroon
source unknown
sporadic
sporadic
W
W
W
2881
11
CC175
CC11/ET-37
2001
2004
1993
2002
1995
2007
2001
2002
2012
Central African
Republic
Djibouti
France
France
Gambia
Mali
Mauritius
Senegal
United States
sporadic
sporadic
sporadic
sporadic
sporadic
sporadic
sporadic
sporadic
sporadic
W
W
W
W
W
W
W
W
W
11
11
22
11
11
11
11
11
CC11/ET-37
CC11/ET-37
CC22
CC11/ET-37
CC11/ET-37
CC11/ET-37
CC11/ET-37
CC11/ET-37
M22748
M22801
M22471
M22751
M07165
M22189
M22718
M22772
M25543
CC
PorA, FetA, 16S, FHbp, NadA, NhbA etc? 21
Strain collection
Meningitis Belt
Country
Non-Belt African
Country
Others
Burkina Faso
Algeria
France
Benin
Djibouti
United State
Cameroon
Mauritius
Saudi Arabia
Chad
South Africa
Central African of
Republic
Gambia
Mali
Niger
Senegal
Togo
22
23
Strain collection
Submission type
Epidemic vs Endemic
Outbreak vs sporadic
Serogroup
W
A
X
24
Strain collection
Lab ID
M09261
M09293
M24695
M23413
M22471
M22751
M22189
M25087
M22811
M22831
M07293
M25419
M23347
M25543
Year
2002
2002
2010
2011
1993
2002
2007
2012
2006
2009
2000?
2005
2011
2012
Country
Burkina Faso
Burkina Faso
Burkina Faso
Burkina Faso
France
France
Mali
Mali
Niger
Niger
South Africa
South Africa
United States
United States
25
Nov 18-28, 2013
Nov 12-14,
2013
March 6,
2013
unpublished
26
Capsular Switching
Allelic exchange of serogroup-specific gene
(Swartley et al 1997)
A capsule switching event is defined as an
isolate of a certain serogroup belonging to a
clonal complex that is commonly associated
with a different serogroup.
A possible mechanism to escape the host
immune system
27
Genogroup-specific
Capsule Transport Capsule Biosynthesis
Genogroup
B
tex ctrD ctrC
ctrB
ctrA
cssA
cssB cssC
csb
C
tex ctrD ctrC
ctrB
ctrA
cssA
cssB cssC
csc
Y
tex ctrD ctrC
ctrB
ctrA
cssA cssB cssC
csy
galE
W
tex ctrD ctrC
ctrB
ctrA
cssA
csw
galE
X
tex ctrD ctrC
ctrB
ctrA
csxA
csxB csxC galE
A
tex ctrD ctrC
ctrB
ctrA
csaA
csaB csaC csaD
NG
tex
galE
cssB cssC
galE
galE
galE
…other genetic mutations possible
28
Capsular switching events among the US
isolates from 2006-10, ABCs
 Serogroup B to C (n=56)
 Switching from C to B (n=10)
 Switching between Y and W in both directions
(n=10).
 Switching from B/C to Y/W (n=4) and Y/W to B/C
(n=7)
 Switching from B, C, Y and W to other serogroups
(n=9)
29


CC11/ET-37 complex is usually associated with
serogroup C.
Capsule switching might have occurred between
serogroups W and C, but when and in which
direction is not known
30
Acknowledgement
CDC MVPDB Meningitis Laboratory
CDC MVPDB epidemiology team
National Reference Laboratories (CHUP-CDG,
CHU-YO, CHU-SS, and CM, Burkina Faso)
National Reference Laboratory, Mali
Dr. Pierre Nicolas, former WHO CC, France
31