Natural immunity against capsular group X N. meningitidis following an outbreak in Togo, 2007

Abstract

In Togolese individuals, the concentration of serum IgG against XPS was higher among the two older age groups as compared to the youngest age group. Antibody concentrations against MenX PS correlated significantly with SBA titers. This supports further development of a MenX PS based conjugate vaccine. Further studies are needed to verify the ability of MenX PS to induce SBA in humans.

Safety and immunogenicity of a pentavalent meningococcal conjugate vaccine containing serogroups A, C, Y, W, and X in healthy adults: a phase 1, single-centre, double-blind, randomised, controlled study

“…However, significant rSBA titres against serogroup X have been observed during outbreaks in 2007. 27 The striking reduction of serogroup A invasive disease since the introduction of MenAfriVac has generated hope for the potential for elimination of meningococcal disease outbreaks in sub-Saharan Africa. By contrast with the annual incidence of meningococcal disease of more than 100 cases per 100 000 individuals before 2010, there were only two cases of invasive serogroup A disease documented for 2017.…”

“…The PHE rSBA assays for serogroups A and C are internationally standardised assays; 26 the rSBA assay method was adapted for serogroups Y, W, and X, as previously published. [27][28][29] The target strains in the rSBA assays were: serogroup A F8238, serogroup C C11, serogroup Y S1975, serogroup W M01 240070, and serogroup X BF2/97. 27 Increases in serogroup C rSBA titres of eight times or more are deemed as an appropriate conservative threshold of protection in seronegative individuals, 30 and an increase in rSBA titres of 128 times or more has been proposed as an appropriate threshold for correlate of protection in seropositive individuals.…”

“…[27][28][29] The target strains in the rSBA assays were: serogroup A F8238, serogroup C C11, serogroup Y S1975, serogroup W M01 240070, and serogroup X BF2/97. 27 Increases in serogroup C rSBA titres of eight times or more are deemed as an appropriate conservative threshold of protection in seronegative individuals, 30 and an increase in rSBA titres of 128 times or more has been proposed as an appropriate threshold for correlate of protection in seropositive individuals. 31 Thus we used rSBA titre thresholds of eight times or more and 128 times or more in our analysis.…”