Vaccine 31 (2013) 1113–1116 Contents lists available at SciVerse ScienceDirect Vaccine jou rn al h om epa ge: www.elsevier.com/locate/vaccine Could the multicomponent meningococcal serogroup B vaccine (4CMenB) control Neisseria meningitidis capsular group X outbreaks in Africa? Eva Hong a , Marzia Monica Giuliani b , Ala-Eddine Deghmane a , Maurizio Comanducci b , Brunella Brunelli b , Peter Dull b , Mariagrazia Pizza b , Muhamed-Kheir Taha a,∗ a Institut Pasteur, Invasive Bacterial Infections Unit, Paris, France b Novartis Vaccines and Diagnostics, Siena, Italy a r t i c l e i n f o Article history: Received 17 August 2012 Received in revised form 6 December 2012 Accepted 8 December 2012 Available online 20 December 2012 Keywords: Neisseria meningitidis Vaccine Serogroup X Epidemics African meningitis belt a b s t r a c t A new vaccine, 4CMenB, is composed of surface proteins of Neisseria meningitidis and is aimed to target serogroup B (MenB) isolates. The vaccine components are present in meningococcal isolates of other serogroups allowing potential use against meningococcal isolates belonging to non-B serogroups. Isolates of serogroup X (MenX) have been emerged in countries of the African meningitis belt. 4CMenB may offer a vaccine strategy against these isolates as there is no available capsule-based vaccine against MenX. We used the Meningococcal Antigen Typing System (MATS) to determine presence, diversity and levels of expression of 4CMenB antigens among 9 MenX isolates from several African countries in order to estimate the potential coverage of MenX by the 4CMenB vaccine. We performed bactericidal assays against these isolates, using pooled sera from 4CMenB-vaccinated infants, adolescents and adults. The African MenX isolates belonged to the same genotype but showed variation in the vaccine antigens. MATS data and bactericidal assays suggest coverage of the 9 African MenX isolates by 4CMenB but not of two unrelated MenX isolates from France. 4CMenB vaccine can be considered for further investigation to control MenX outbreaks in Africa. © 2012 Elsevier Ltd. All rights reserved. 1. Introduction Neisseria meningitidis (Nm), a human exclusive encapsulated bacterium, may provoke invasive infections that are dominated by septicaemia and meningitis. Sporadic cases occur in Europe and North America. Major periodic epidemics have been occurring in the African sub-Saharan countries from Ethiopia to Senegal [1]. The polysaccharide capsule determines the serogroup of isolates and 12 meningococcal capsular groups are currently described. Serogroups A, B, C, Y, W and X are responsible for the majority of invasive meningococcal infections worldwide [2]. Epidemics in the African meningitis belt are largely due to isolates of capsular group A (MenA). Outbreaks due to isolates of serogroups W and X (MenW and MenX) were also reported [3–10]. Currently licensed vaccines are composed of plain or conju- gate capsular polysaccharides and directed against isolates of serogroups A, C, Y and W. In particular, a conjugate MenA vaccine has been recently licensed and is being used in several countries of the meningitis belt [11]. The polysaccharide of MenB is poorly immunogenic as it is homologous to the neural cell adhesion ∗ Corresponding author. Tel.: +33 1 45 68 84 38; fax: +33 1 45 68 83 38. E-mail address: mktaha@pasteur.fr (M.-K. Taha). molecules NCAMs [12,13]. No capsule-based vaccine against MenB is available. A recombinant vaccine containing 4 components (4CMenB) has been developed, with three novel genome-derived proteins fHbp (factor H binding protein), NHBA (Neisseria Heparin Binding Antigen), and NadA (Neisserial adhesin A) as well as the outer membrane vesicles expressing porin A (PorA) serosubtype P1.4 [14]. An approach based on sequencing of these genes to anal- yse their polymorphism as well as on the determination of their levels of expression by determining the subtype P1.4 and using the Meningococcal Antigen Typing System (MATS) protocol has been developed to predict coverage by the 4CMenB vaccine against serogroup B meningococcal strains. It measures immunologic cross-reactivity and quantity of expressed antigens NHBA, NadA, and fHbp. The MATS values of these proteins are referred to as the relative potency (RP) of a given antigen in an unknown strain in comparison to a reference strain. The MATS also predicts killing (at ≥80% probability) of an isolate by Serum bactericidal assays (SBA) if its RP value for any of the three vaccine antigens is higher than a threshold called positive bactericidal threshold (PBT) [15]. The antigens in the 4CMenB vaccine may be present in all meningococcal isolates regardless the serogroup. The recent description of MenX outbreaks in Niger and other African countries highlights the need for a new conjugate vaccine-based approach to prevention [3,16]. Although a capsule-based vaccine approach 0264-410X/$ – see front matter © 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.vaccine.2012.12.022