Project description:Treatment of pneumococcal infections is limited by antibiotic resistance and exacerbation of disease by bacterial lysis releasing pneumolysin toxin and other inflammatory factors. We identified a novel peptide in the Klebsiella pneumoniae secretome, which enters Streptococcus pneumoniae via its AmiA-AliA/AliB permease. Subsequent downregulation of genes for amino acid biosynthesis and peptide uptake was associated with reduction of pneumococcal growth in defined medium and human cerebrospinal fluid, irregular cell shape, decreased chain length and decreased genetic transformation. The bacteriostatic effect was specific to S. pneumoniae and Streptococcus pseudopneumoniae with no effect on Streptococcus mitis, Haemophilus influenzae, Staphylococcus aureus or K. pneumoniae. Peptide sequence and length were crucial to growth suppression. The peptide reduced pneumococcal adherence to primary human airway epithelial cell cultures and colonization of rat nasopharynx, without toxicity. We also analysed the effect of peptide on the proteome of S. pneumoniae. We found alteration of the proteome by the peptide with some proteins turned on or off in line with the transcriptomic changes. We therefore identified a peptide with potential as a therapeutic for pneumococcal diseases suppressing growth of multiple clinical isolates, including antibiotic resistant strains, while avoiding bacterial lysis and dysbiosis.
Project description:Nonencapsulated Streptococcus pneumoniae (NESp) is an emerging human pathogen that colonizes the nasopharynx and is associated with noninvasive disease such as otitis media (OM), conjunctivitis, and nonbacteremic pneumonia. For decades, expression of a polysaccharide capsule appeared to be necessary for establishment of colonization and development of invasive pneumococcal disease (IPD). Accordingly, the currently licensed pneumococcal vaccines target the polysaccharide capsule. However, NESp expressing the novel oligopeptide importer proteins AliC and AliD have been isolated during IPD. Our study reveals that NESp expressing AliC and AliD have intensified virulence compared to isogenic mutants, and we provide insight about how this pneumococcal population has become associated with IPD. Our data demonstrates that AliC and AliD enhance murine nasopharyngeal colonization and are required for OM in a chinchilla model. Furthermore, AliC and AliD increase pneumococcal survival in chinchilla whole blood and decrease deposition of human C3b on the bacterial surface. As NESp become an increasing threat to public health, our study exposes specific virulence factors to possibly target for a broadened prevention of IPD through vaccination.
Project description:Streptococcus pneumoniae (the pneumococcus) continues to be responsible for a high level of global morbidity and mortality resulting from pneumonia, bacteremia, meningitis, and otitis media. Here we have used a novel technique involving niche-specific, genome-wide in vivo transcriptomic analyses to identify genes upregulated in distinct niches during pathogenesis after intranasal infection of mice with serotype 4 or 6A pneumococci. The analyses yielded 28 common, significantly upregulated genes in the lungs relative to those in the nasopharynx and 25 significantly upregulated genes in the blood relative to those in the lungs in both strains, some of which were previously unrecognized. The role of five upregulated genes from either the lungs or the blood in pneumococcal pathogenesis and virulence was then evaluated by targeted mutagenesis. One of the mutants (delta malX) was significantly attenuated for virulence in the lungs, two (delta aliA and delta ilvH) were significantly attenuated for virulence in the blood relative to the wild type, and two others (delta cbiO and delta piuA) were completely avirulent in a mouse intranasal challenge model. We also show that the products of aliA, malX, and piuA are promising candidates for incorporation into multicomponent protein-based pneumococcal vaccines currently under development. Importantly, we suggest that this new approach is a viable complement to existing strategies for the discovery of genes critical to the distinct stages of invasive pneumococcal disease and potentially has broad application for novel protein antigen discovery in other pathogens such as S. pyogenes, Haemophilus influenzae type b, and Neisseria meningitidis. [Data is also available from http://bugs.sgul.ac.uk/E-BUGS-133]
Project description:Streptococcus pneumoniae is a major cause of invasive diseases, such as pneumoniae, meningitis and sepsis resulting in high mortality. The molecular mechanisms and disease developing mechanism underlying pneumococcal infection remain unknown. Previously, we reported that S. pneumoniae β-galactosidase (BgaA) is evolutionarily conserved and contributes to pneumococcal pathogenesis in mouse sepsis model. BgaA is also known to play a role in pneumococcal growth, resistance to human neutrophil opsonophagocytic killing, bacterial adherence to human epithelial cells. In this study, since the detailed role that BgaA plays in sepsis remain unknown, we focused on the role of BgaA in pneumococcal sepsis. Our in vitro assays showed that BgaA promoted bacterial association with human lung epithelial and vascular endothelium cells. BgaA also contributes to pneumococcal survival with human blood by suppressing neutrophils killing, whereas BgaA did not affect pneumococcal survival in mouse blood. In a mouse sepsis model, mice infected with S. pneumoniae bgaA deletion mutant strain exhibited up-regulated host innate immunity pathways, and suppressed tissue damages and blood coagulation as compared to mice infected with the wild-type strain. These results suggest that BgaA works as a multifunctional virulence factor for inducing host tissue damages and blood coagulation. BgaA could be an attractive target for drug and vaccine development.
Project description:Analysis of pulmonary gene expression in two mouse strains, resistant (BALB/c) and susceptible (CBA/Ca) to Streptococcus pneumoniae infection. Data collected at 6h post-infection and for control animals (PBS-treated). The list of differentially expressed genes was created by comparisons of infected versus PBS-treated animals and PBS-treated BALB/c versus CBA/Ca. The hypothesis tested in the present study was that pulmonary transcriptomes of both mouse strains differ during pneumococcal infection and in non-disease conditions. Results provided important information on differences in immune responses between both mouse strains. The results identified genes and pathways uniquely regulated by only one of the tested mouse strains helping to understand molecular mechanism behind resistance or susceptibility to pneumococcal infections. Total RNA obtained from lung tissue from BALB/cOlaHsd and CBA/CaOlaHsd mouse strains (Harlan) 6 hours post intranasal infection with Streptococcus pneumoniae serotype 2 strain D39 dose 5.0E06 or PBS-treated animals
Project description:Galactose promotes pneumococcal biofilms in vivo 15 mRNA profiles of Streptococcus pneumoniae samples that were grown under different conditions were generated using deep sequencing.
Project description:Analysis of pulmonary gene expression in two mouse strains, resistant (BALB/c) and susceptible (CBA/Ca) to Streptococcus pneumoniae infection. Data collected at 6h post-infection and for control animals (PBS-treated). The list of differentially expressed genes was created by comparisons of infected versus PBS-treated animals and PBS-treated BALB/c versus CBA/Ca. The hypothesis tested in the present study was that pulmonary transcriptomes of both mouse strains differ during pneumococcal infection and in non-disease conditions. Results provided important information on differences in immune responses between both mouse strains. The results identified genes and pathways uniquely regulated by only one of the tested mouse strains helping to understand molecular mechanism behind resistance or susceptibility to pneumococcal infections.
Project description:Influenza A virus (IAV) predisposes individuals to secondary infections with the bacterium Streptococcus pneumoniae (the pneumococcus). Infections may manifest as pneumonia, sepsis, meningitis or otitis media (OM). It remains controversial as to whether secondary pneumococcal disease is due to the induction of an aberrant immune response or IAV induced immunosuppression. Moreover, as the majority of studies have been performed in the context of pneumococcal pneumonia, it remains unclear how far these findings can be extrapolated to other pneumococcal disease phenotypes. Here, we demonstrate that the viral hemagglutinin (HA) mediates bacterial OM by inducing a pro-inflammatory response in the middle ear cavity in a replication-dependent manner. Importantly, our findings show that it is the inflammatory response that mediates pneumococcal replication; not viral suppression of the immune system or epithelial damage. This study provide the first evidence that HA induced inflammation drives pneumococcal replication in the middle ear cavity, which has important consequences to the treatment of pneumococcal OM.
Project description:In the present study, we used RNA sequencing on mouse splenocytes to describe the immune recall in the days following pneumococcal lung infection. Mice were sacrificed at days 1, 2, 4, and 7 after Streptococcus pneumoniae (TIGR4 serotype 4) intranasal infection and splenocytes were cultured in the presence or absence of the same inactivated bacterial strain to access the transcriptomic profile.
Project description:Comparative genomic hybridisation of Streptococcus pneumoniae isolates from a single clonal complex, in order to determine genomic diversity. Isolates were selected from a range of tissue types and serotypes in order to cover the full diversity of the clone, and also in order to try and identify tissue-specific genes Biological replicates: 19 clonal complex 199 S. pneumoniae isolates. One clonal complex 180 isolate used as an outgroup. Independently grown and isolated. One isolate per array