A high-throughput sequencing approach identifies immunotherapeutic targets for bacterial meningitis in neonates

Abstract

AbstractBackgroundWorldwide,Escherichia coliis the leading cause of neonatal Gram-negative bacterial meningitis, but full understanding of the pathogenesis of this disease is not yet achieved. Moreover, to date, no vaccine is available against bacterial neonatal meningitis.MethodsHere, we used Transposon Sequencing of saturated banks of mutants (TnSeq) to evaluateE. coliK1 genetic fitness in murine neonatal meningitis. We identifiedE. coliK1 genes encoding for factors important for systemic dissemination and brain infection, and focused on products with a likely outer-membrane or extra-cellular localization, as these are potential vaccine candidates. We usedin vitroandin vivomodels to study the efficacy of active and passive immunization.ResultsWe selected for further study the conserved surface polysaccharide Poly-β-(1-6)-N-Acetyl Glucosamine (PNAG), as a strong candidate for vaccine development. We found that PNAG was a virulence factor in our animal model. We showed that both passive and active immunization successfully prevented and/or treated meningitis caused byE. coliK1 in neonatal mice. We found an excellent opsonophagocytic killing activity of the antibodies to PNAG andin vitrothese antibodies were also able to decrease binding, invasion and crossing ofE. coliK1 through two blood brain barrier cell lines. Finally, to reinforce the potential of PNAG as a vaccine candidate in bacterial neonatal meningitis, we demonstrated that Group BStreptococcus, the main cause of neonatal meningitis in developed countries, also produced PNAG and that antibodies to PNAG could protectin vitroandin vivoagainst this major neonatal pathogen.InterpretationAltogether, these results indicate the utility of a high-throughput DNA sequencing method to identify potential immunotherapy targets for a pathogen, including in this study a potential broad-spectrum target for prevention of neonatal bacterial infections.FundingsANR Seq-N-Vaq, Charles Hood Foundation, Hearst Foundation. Groupe Pasteur Mutualité