title: Construction of Opa-positive and Opa-negative strains of Neisseria meningitidis to evaluate a novel meningococcal vaccine.
abstract: Neisseria meningitidis is a major global pathogen causing invasive disease with a mortality of 5-10%. Most disease in developed countries is caused by serogroup B infection, against which there is no universal vaccine. Opacity-associated adhesin (Opa) proteins are major meningococcal outer membrane proteins, which have shown recent promise as a potential novel vaccine. Immunisation of mice with different Opa variants elicited high levels of meningococcal-specific bactericidal antibodies, demonstrating proof in principle for this approach. Opa proteins are critical in meningococcal pathogenesis, mediating bacterial adherence to host cells, and modulating human cellular immunity via interactions with T cells and neutrophils, although there are conflicting data regarding their effects on CD4(+) T cells. We constructed Opa-positive and Opa-negative meningococcal strains to allow further evaluation of Opa as a vaccine component. All four opa genes from N. meningitidis strain H44/76 were sequentially disrupted to construct all possible combinations of N. meningitidis strains deficient in one, two, three, or all four opa genes. The transformations demonstrated that homologous recombination of exogenous DNA into the meningococcal chromosome can occur with as little as 80 bp, and that minor sequence differences are permissible. Anti-Opa bactericidal antibody responses following immunisation of mice with recombinant Opa were specific to the Opa variant used in immunisation. No immunomodulatory effects were observed when Opa was contained within meningococcal outer membrane vesicles (OMVs), compared to Opa-negative OMVs. These observations support the incorporation of Opa in meningococcal vaccines.
authors.affiliation: Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom. manish.sadarangani@paediatrics.ox.ac.uk
authors.forename: Manish
authors.initials: M
authors.lastname: Sadarangani
authors.forename: J Claire
authors.initials: JC
authors.lastname: Hoe
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Callaghan
authors.forename: Claire
authors.initials: C
authors.lastname: Jones
authors.forename: Hannah
authors.initials: H
authors.lastname: Chan
authors.forename: Katherine
authors.initials: K
authors.lastname: Makepeace
authors.forename: Hélène
authors.initials: H
authors.lastname: Daniels-Treffandier
authors.forename: Mary E
authors.initials: ME
authors.lastname: Deadman
authors.forename: Christopher
authors.initials: C
authors.lastname: Bayliss
authors.forename: Ian
authors.initials: I
authors.lastname: Feavers
authors.forename: Peter
authors.initials: P
authors.lastname: van der Ley
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Pollard
mesh_terms: D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics* / Q000276:immunology; D007114:Immunization; D008585:Meningitis, Meningococcal / Q000276:immunology / Q000517:prevention & control*; D022401:Meningococcal Vaccines / Q000276:immunology*; D051379:Mice; D009345:Neisseria meningitidis / Q000235:genetics / Q000276:immunology*; D011994:Recombinant Proteins / Q000235:genetics* / Q000276:immunology
chemical_list: D001425:Bacterial Outer Membrane Proteins; D022401:Meningococcal Vaccines; D011994:Recombinant Proteins; C090348:Opa protein, Neisseria