title: Contribution of serotype and genetic background to virulence of serotype 3 and serogroup 11 pneumococcal isolates.
abstract: The capsular serotype has long been associated with the virulence of Streptococcus pneumoniae. Here we present an in-depth study of phenotypic and genetic differences between serotype 3 and serogroup 11 S. pneumoniae clinical isolates from both the general and indigenous populations of Australia. Both serotypes/groups included clonally unrelated strains with differences in well-known polymorphic virulence genes, such as nanA and pspA, as demonstrated by multilocus sequence typing and Western blot analysis. Nonetheless, the serotype 3 strains were consistently and significantly more virulent in mice than the serogroup 11 strains. Despite extensive genomic analysis, noncapsular genes common to one serotype/group but not the other were not identified. Nevertheless, following the conversion of a serotype 11A isolate to serotype 3 and subsequent analysis in an intranasal infection model, it was evident that both capsular and noncapsular factors determine the virulence phenotype in mice. However, it appears that these noncapsular factors vary from strain to strain.
authors.affiliation: Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, University of Adelaide, Adelaide 5005, South Australia, Australia.
authors.forename: Lauren J
authors.initials: LJ
authors.lastname: McAllister
authors.forename: Abiodun D
authors.initials: AD
authors.lastname: Ogunniyi
authors.forename: Uwe H
authors.initials: UH
authors.lastname: Stroeher
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Leach
authors.forename: James C
authors.initials: JC
authors.lastname: Paton
mesh_terms: D000818:Animals; D002475:Cellobiose; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D014644:Genetic Variation; D044404:Genomic Islands; D051379:Mice; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity*; D014774:Virulence
chemical_list: D002475:Cellobiose