Induction of Susceptibility to Disseminated Infection with IgA1 Protease-Producing Encapsulated Pathogens Streptococcus pneumoniae, Haemophilus influenzae Type b, and Neisseria meningitidis

This is the authors' abstract. We don't add key points for this paper.

Why some individuals develop invasive infection, including meningitis, with Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae type b is unexplained. The vast majority of humans are colonized with the three pathogens but remain healthy and develop immunity. The findings of this study support the hypothesis that patients are primed for disease by time-shifted acquisition of two different bacteria, an immunogenic commensal followed by the pathogen, but both expressing the same capsular polysaccharide. The IgA1 protease common to the three pathogens cleaves the preexisting IgA1 antibodies induced by the commensal. This eliminates Fc-mediated protective mechanisms and releases capsule-binding monomeric Fab fragments that enhance bacterial adherence and block access of other isotypes of antibody molecules. This concept provides new insight into the pathogenesis of bacterial meningitis and potential new strategies for prevention.