Laboratory Predictors of Meningococcal Disease And Vaccination in Children: studies on the host immune response against Neisseria meningitidis

Abstract

Neisseria meningitidis is a gram-negative diplococcus which was first identified by Anton Weichselbaum in 1887. Strains of N. meningitidis can be classified into serogroups based upon the different composition of its capsular polysaccharide. Thirteen serogroups have been identified, of which serogroups A, B, C, W135 and Y are responsible for invasive disease. Additional subclassification is based on the variability of two outer membrane proteins: PorB and PorA. Antigenic variation in PorB is responsible for classification of meningococci into serotypes, whereas PorA is responsible for serosubtyping (www.neisseria.org/nm/typing). The outer membrane of N. meningitidis also contains lipopolysaccharide (LPS). The variability of the core structure of LPS is the basis of classification of N. meningitidis into at least 12 different immunotypes. N. meningitidis is an exclusively human pathogen and asymptomatic nasopharyngeal carriage among the population is approximately 7-17%. The carriage rate increases up to 45% when estimated by the culture of tonsillar tissue harvested on tonsillectomy.