Dynamics of carriage of Neisseria meningitidis in a group of military recruits: subtype stability and specificity of the immune response following colonisation

Meningococcal carriage and the immune response to colonization were studied in a group of military recruits undergoing basic training. Subtyping by determination of the class 1 protein se-quence clearly differentiated between strains and demonstrated the dynamics of carriage and trans-mission. Expression of class 1 protein by each strain remained stable during prolonged carriage by different subjects. Following colonization, a marked increase in serum bactericidal response occurred, which was specific for the subtype of the acquired strain and was associated with an increase in reactivity by Western blot to the homologous class 1 protein. Subjects colonized by multiple strains showed evidence of a specific immune response to the class 1 protein of each strain acquired. The subtype specificity of the bactericidal response to meningococci and the stability of expression of the class 1 protein have important implications for the design of vaccines for prevention of serogroup B meningococcal disease. Meningococcal disease is still a worldwide public health risk. Since early studies by Heist et al. [4], it has become generally In most instances, meningococci merely colonize the human accepted that immunity to meningococcal disease is dependent nasopharynx, but when invasive disease occurs, it has the po- on the presence of serum bactericidal activity directed toward tential to cause rapid and devastating illness in previously the infecting organism. Identification of the serogroup-specifi