Xin Wang, Ph.D Meningitis Laboratory CDC 1

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 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 vaccine- induced 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 ( 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). Maiden, M., et al PNAS abcZadkaroEfumCgdhpdhCpgmSTCC 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Strain genotypes with significant changes between and , ABCs (Wang et al unpublished) 7

 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 Meningococcal disease 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 pre- MenAfriVac 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 MenAfriVac-Vaccine-an-Amazing-Success-Story-in-Global- Health 10

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

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 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  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 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

No. of Isolates Clonal Complex TotalCC22CC11CC23CC174CC167CC168unassigned (Wang et al unpublished)  Accounts for <5% of invasive meningococcal disease in the United States  14 W cases in South FL, (6 cases during )  CC11/ST11, and similar to the Hajj clone by PFGE 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

Clonal ComplexNo. (%) isolates CC1166 CC231 CC17538 NmW strains in the meningitis belt between 2004 and 2010, Pre-MenAfriVac Caugant DA, Kristiansen PA, Wang X, Mayer LW, et al. (2012) PLoS ONE 7(9): e46019.doi: /journal.pone

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 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

PorA, FetA, 16S, FHbp, NadA, NhbA etc? 21

Meningitis Belt Country Non-Belt African Country Others Burkina FasoAlgeriaFrance BeninDjiboutiUnited State CameroonMauritiusSaudi Arabia ChadSouth Africa Central African of Republic Gambia Mali Niger Senegal Togo Strain collection 22

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Strain collection Submission type Epidemic vs Endemic Outbreak vs sporadic Serogroup W A X 24

Strain collection Lab IDYearCountry M Burkina Faso M Burkina Faso M Burkina Faso M Burkina Faso M France M France M Mali M Mali M Niger M Niger M ?South Africa M South Africa M United States M United States 25

unpublished Nov 18-28, 2013 Nov 12-14, 2013 March 6,

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

B cssAcssBcssCctrBctrDctrAtex ctrC galEcsb A csaAcsaBcsaCctrBctrDctrAtex ctrC csaD galE C cssAcssBctrBctrDctrAtex ctrC cssC csc galE Y cssBcssCcsyctrBctrDctrAtex ctrCcssA galE W cssAcssBcssCcswctrBctrDctrAtex ctrC galE NG tex galE …other genetic mutations possible X ctrBctrDctrAtex ctrC csxAcsxBcsxC galE Capsule Transport Genogroup-specific Capsule Biosynthesis Genogroup 28

Capsular switching events among the US isolates from , 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