Molecular characterization of invasive meningococcal isolates from countries in the African meningitis belt before introduction of a serogroup A conjugate vaccine.

Dominique A Caugant,Denis Kandolo,Paul A Kristiansen,Laurence Bonte,Rasmata Ouédraogo,Muhamed-Kheir Taha,Samba Sow,Flabou Bougoudogo,Xin Wang,Leonard W Mayer,Ray Borrow

doi:10.1371/journal.pone.0046019

Dominique A Caugant, Denis Kandolo + Show 9 more

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https://doi.org/10.1371/journal.pone.0046019

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Journal: PloS one	Publication Date: Sep 27, 2012
Citations: 71	License type: CC0 1.0

Affiliation: Norwegian Institute of Public Health, Institut Pasteur

Abstract

BackgroundThe serogroup A conjugate meningococcal vaccine, MenAfriVac, was introduced in mass vaccination campaigns in December 2010 in Burkina Faso, Mali and Niger. In the coming years, vaccination will be extended to other African countries at risk of epidemics. To document the molecular characteristics of disease-causing meningococcal strains circulating in the meningitis belt of Africa before vaccine introduction, the World Health Organization Collaborating Centers on Meningococci in Europe and United States established a common strain collection of 773 isolates from cases of invasive meningococcal disease collected between 2004 and 2010 from 13 sub-Saharan countries.MethodologyAll isolates were characterized by multilocus sequence typing, and 487 (62%) were also analyzed for genetic variation in the surface antigens PorA and FetA. Antibiotic susceptibility was tested for part of the collection.Principal FindingsOnly 19 sequence types (STs) belonging to 6 clonal complexes were revealed. ST-5 clonal complex dominated with 578 (74.8%) isolates. All ST-5 complex isolates were remarkably homogeneous in their PorA (P1.20,9) and FetA (F3-1) and characterized the serogroup A strains which have been responsible for most epidemics during this time period. Sixty-eight (8.8%) of the 773 isolates belonged to the ST-11 clonal complex which was mainly represented by serogroup W135, while an additional 38 (4.9%) W135 isolates belonged to the ST-175 complex. Forty-eight (6.2%) serogroup X isolates from West Africa belonged to the ST-181 complex, while serogroup X cases in Kenya and Uganda were caused by an unrelated clone, ST-5403. Serogroup X, ST-181, emerged in Burkina Faso before vaccine introduction.ConclusionsIn the seven years preceding introduction of a new serogroup A conjugate vaccine, serogroup A of the ST-5 clonal complex was identified as the predominant disease-causing strain.

Highlights

The meningitis belt of Africa was first described by Lapeysonnie in 1963 [1] and was further defined by Molesworth and coworkers in 2002 [2]
In the seven years preceding introduction of a new serogroup A conjugate vaccine, serogroup A of the sequence type (ST)-5 clonal complex was identified as the predominant disease-causing strain
We report here the molecular characteristics of the strains circulating in these countries from 2004 to 2010, prior to MenAfriVac introduction

Summary

Introduction

The meningitis belt of Africa was first described by Lapeysonnie in 1963 [1] and was further defined by Molesworth and coworkers in 2002 [2]. It encompasses parts or the whole of 25 countries south of the Sahara, stretching from Ethiopia in the east to Senegal in the west. Every year during the dry season the region is affected by outbreaks of meningococcal meningitis and large epidemics emerge unpredictably 8 to 10 years apart. Emergence and dissemination of a new strain may lead to epidemics under certain environmental conditions. To document the molecular characteristics of disease-causing meningococcal strains circulating in the meningitis belt of Africa before vaccine introduction, the World Health Organization Collaborating Centers on Meningococci in Europe and United States established a common strain collection of 773 isolates from cases of invasive meningococcal disease collected between 2004 and 2010 from 13 sub-Saharan countries

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Conclusion