Large‐scale identification of serotype 4 Streptococcus pneumoniae virulence factors

DL Hava, A Camilli - Molecular microbiology, 2002 - Wiley Online Library
DL Hava, A Camilli
Molecular microbiology, 2002Wiley Online Library
Streptococcus pneumoniae (the pneumococcus) is carried in the nasopharynx of healthy
individuals, but can spread to other host sites and lead to pneumonia, bacteraemia, otitis
media and meningitis. Although it is logical to think a priori that differential gene expression
would contribute to the ability of this patho‐gen to colonize different sites, in fact very few
genes have been demonstrated to play tissue specific roles in virulence or carriage. Using
signature‐tagged mutagenesis to screen 6149 mariner‐transposon insertion strains, we …
Summary
Streptococcus pneumoniae (the pneumococcus) is carried in the nasopharynx of healthy individuals, but can spread to other host sites and lead to pneumonia, bacteraemia, otitis media and meningitis. Although it is logical to think a priori that differential gene expression would contribute to the ability of this patho‐gen to colonize different sites, in fact very few genes have been demonstrated to play tissue specific roles in virulence or carriage. Using signature‐tagged mutagenesis to screen 6149 mariner ‐transposon insertion strains, we identified 387 mutants attenuated for infection in a murine model of pneumonia. Among these mutants are ones with disruptions in a number of putative tissue‐specific transcriptional regulators, surface proteins, metabolic proteins and proteins of unknown function, most of which had not previously been associated with virulence. A subset of these, including most of those with insertions in putative transcriptional regulators, was examined for phenotypes in murine models of bacteraemia and nasopharyngeal carriage. Four classes of mutants defective in infection models of the: (I) lung, (II) lung and blood, (III) lung and nasopharynx, and (IV) all three tissues were identified, thus demonstrating the ex‐istence of tissue‐specific pneumococcal virulence factors. Included in these strains were two with disruptions in a genetic locus that putatively codes for a transcriptional regulator, three surface proteins and three sortase homologues. Mutation analysis revealed that three of the seven genes in this locus are virulence factors that are specific to mucosal surfaces.
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