title: Construction and immunological characterization of a novel nontoxic protective pneumolysin mutant for use in future pneumococcal vaccines.
abstract: Pneumolysin, the pore-forming toxin produced by Streptococcus pneumoniae, may have an application as an immunogenic carrier protein in future pneumococcal conjugate vaccines. Most of the 90 S. pneumoniae serotypes identified produce pneumolysin; therefore, this protein may confer non-serotype-specific protection against pneumococcal infections such as pneumonia, meningitis, and otitis media. However, as pneumolysin is highly toxic, a nontoxic form of pneumolysin would be a more desirable starting point in terms of vaccine production. Previous pneumolysin mutants have reduced activity but retain residual toxicity. We have found a single amino acid deletion that blocks pore formation, resulting in a form of pneumolysin that is unable to form large oligomeric ring structures. This mutant is nontoxic at concentrations greater than 1,000 times that of the native toxin. We have demonstrated that this mutant is as immunogenic as native pneumolysin without the associated effects such as production of the inflammatory mediators interleukin-6 and cytokine-induced neutrophil chemoattractant KC, damage to lung integrity, and hypothermia in mice. Vaccination with this mutant protects mice from challenge with S. pneumoniae. Incorporation of this mutant pneumolysin into current pneumococcal vaccines may increase their efficacy.
authors.affiliation: Division of Infection and Immunity, Institute of Biomedical and Life Sciences, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, Scotland, UK.
authors.forename: Lea-Ann S
authors.initials: LA
authors.lastname: Kirkham
authors.forename: Alison R
authors.initials: AR
authors.lastname: Kerr
authors.forename: Gill R
authors.initials: GR
authors.lastname: Douce
authors.forename: Gavin K
authors.initials: GK
authors.lastname: Paterson
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Dilts
authors.forename: Dai-Fang
authors.initials: DF
authors.lastname: Liu
authors.forename: Tim J
authors.initials: TJ
authors.lastname: Mitchell
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D005260:Female; D007035:Hypothermia; D007249:Inflammation / Q000378:metabolism; D008168:Lung / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D016297:Mutagenesis, Site-Directed; D011008:Pneumococcal Infections / Q000276:immunology* / Q000517:prevention & control; D022242:Pneumococcal Vaccines / Q000235:genetics* / Q000276:immunology*; D013301:Streptolysins / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D022242:Pneumococcal Vaccines; D013301:Streptolysins; C032290:plY protein, Streptococcus pneumoniae