Neisseria cinerea Expresses a Functional Factor H Binding Protein Which Is Recognized by Immune Responses Elicited by Meningococcal Vaccines

Neisseria meningitidis is a major cause of bacterial meningitis and sepsis worldwide. Capsular polysaccharide vaccines are available against meningococcal serogroups A, C, W and Y. More recently two protein based vaccines, Bexsero® and Trumenba®, have been licenced against meningococcal serogroup B strains; both vaccines contain meningococcal factor H binding protein (fHbp). fHbp is a surface exposed lipoprotein which binds the negative complement regulator, complement factor H (CFH), thereby inhibiting the alternative pathway of complement activation. Recent analysis of available genomes has indicated that some commensal Neisseria species also contain genes that potentially encode fHbp, although the function of these genes and how immunisation with fHbp-containing vaccines could affect the commensal flora have yet to be established. Here we show that the commensal species Neisseria cinerea expresses functional fHbp on its surface and is responsible for recruitment of CFH by the bacterium. N. cinerea fHbp binds CFH at similar affinity as meningococcal fHbp, and promotes survival of N. cinerea in human serum. We examined the potential impact of fHbp-containing vaccines on N. cinerea We found that immunisation with Bexsero® elicits serum bactericidal activity against N. cinerea, which is primarily directed against fHbp. The shared function of fHbp in N. cinerea and N. meningitidis, and cross reactive responses elicited by Bexsero® suggest that the introduction of fHbp-containing vaccines has the potential to affect carriage of N. cinerea and other commensal species.