title: Characterization of vaccine antigens of meningococcal serogroup W isolates from Ghana and Burkina Faso from 2003 to 2009.
abstract: Neisseria meningitidis is a major cause of bacterial meningitis and a considerable health problem in the 25 countries of the 'African Meningitis Belt' that extends from Senegal in West Africa to Ethiopia in the East. Approximately 80% of cases of meningococcal meningitis in Africa have been caused by strains belonging to capsular serogroup A. After the introduction of a serogroup A conjugate polysaccharide vaccine, MenAfriVac (™), that began in December 2010, the incidence of meningitis due to serogroup A has markedly declined in this region. Currently, serogroup W of N. meningitidis accounts for the majority of cases. Vaccines based on sub-capsular antigens, such as Generalized Modules for Membrane Antigens (GMMA), are under investigation for use in Africa. To analyse the antigenic properties of a serogroup W wave of colonisation and disease, we investigated the molecular diversity of the protein vaccine antigens PorA, Neisserial Adhesin A (NadA), Neisserial heparin-binding antigen (NHBA) and factor H binding protein (fHbp) of 31 invasive and carriage serogroup W isolates collected as part of a longitudinal study from Ghana and Burkina Faso between 2003 and 2009. We found that the isolates all expressed fHbp variant 2 ID 22 or 23, differing from each other by only one amino acid, and a single PorA subtype of P1.5,2. Of the isolates, 49% had a functional nhbA gene and 100% had the nadA allele 3, which contained the insertion sequence IS1301 in five isolates. Of the W isolates tested, 41% had high fHbp expression when compared with a reference serogroup B strain, known to be a high expresser of fHbp variant 2. Our results indicate that in this collection of serogroup W isolates, there is limited antigenic diversification over time of vaccine candidate outer membrane proteins (OMP), thus making them promising candidates for inclusion in a protein-based vaccine against meningococcal meningitis for Africa.
authors.affiliation: Novartis Vaccines Institute for Global Health, 53100, Siena, Italy ; MRC Centre for Immune Regulation, School of Immunity and Infection, College of Medicine and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK ; Molecular Immunology Department, Swiss Tropical and Public Health Institute, Basel, 4002, Switzerland.
authors.forename: Emma
authors.initials: E
authors.lastname: Ispasanie
authors.affiliation: Molecular Immunology Department, Swiss Tropical and Public Health Institute, Basel, 4002, Switzerland ; University of Basel, Basel, 4003, Switzerland.
authors.forename: Gerd
authors.initials: G
authors.lastname: Pluschke
authors.affiliation: Navrongo Health Research Centre, Navrongo, PO Box 114, Ghana.
authors.forename: Abraham
authors.initials: A
authors.lastname: Hodgson
authors.affiliation: Centre de Recherche en Santé de Nouna, PO Box 02, Nouna, Burkina Faso.
authors.forename: Ali
authors.initials: A
authors.lastname: Sie
authors.affiliation: Novartis Vaccines Institute for Global Health, 53100, Siena, Italy ; MRC Centre for Immune Regulation, School of Immunity and Infection, College of Medicine and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK.
authors.forename: Calman
authors.initials: C
authors.lastname: MacLennan
authors.affiliation: Novartis Vaccines Institute for Global Health, 53100, Siena, Italy.
authors.forename: Oliver
authors.initials: O
authors.lastname: Koeberling
keywords: Neisseria meningitidis; meningococcus; meningitis; serogroup W; factor H binding protein; NadA, NHBA