Project description:Diagnostic primer extension assay to serotype Streptococcus pneumoniae. Assay validation. Background: Monitoring of Streptococcus pneumoniae serotype epidemiology is essential since serotype replacement is a concern when introducing new polysaccharide-conjugate vaccines. To simplify S. pneumoniae serotyping, a novel PCR-based automated microarray assay was developed to assist in the tracking of the serotypes. Results: Autolysin (lytA), pneumolysin (ply) and eight genes located in the capsular operon (cps) were amplified using multiplex PCR. This step was followed by a tagged fluorescent primer extension step targeting serotype-specific polymorphisms. The tagged primers were then hybridized to a microarray. Results were exported to an expert system that transforms genetic typing data into capsular serotype identification. The assay was validated on 166 cultured S. pneumoniae samples from 63 different serotypes as determined by the Quellung method. In addition, the assay was tested on clinical specimens including 43 cerebrospinal fluid samples from patients with meningitidis and 59 nasopharyngeal aspirates from bacterial pneumonia patients. The assay presented with no cross-reactivity for 24 relevant bacterial species found in these types of samples. The limit of detection for serotyping and S. pneumoniae detection was 100 genome equivalent per reaction. Conclusion: This automated assay is amenable to clinical testing and does not require any culturing of the samples. The assay will be useful for the evaluation of serotype prevalence changes after new conjugate vaccines introduction.
Project description:Diagnostic primer extension assay to serotype Streptococcus pneumoniae. Assay validation. Background: Monitoring of Streptococcus pneumoniae serotype epidemiology is essential since serotype replacement is a concern when introducing new polysaccharide-conjugate vaccines. To simplify S. pneumoniae serotyping, a novel PCR-based automated microarray assay was developed to assist in the tracking of the serotypes. Results: Autolysin (lytA), pneumolysin (ply) and eight genes located in the capsular operon (cps) were amplified using multiplex PCR. This step was followed by a tagged fluorescent primer extension step targeting serotype-specific polymorphisms. The tagged primers were then hybridized to a microarray. Results were exported to an expert system that transforms genetic typing data into capsular serotype identification. The assay was validated on 166 cultured S. pneumoniae samples from 63 different serotypes as determined by the Quellung method. In addition, the assay was tested on clinical specimens including 43 cerebrospinal fluid samples from patients with meningitidis and 59 nasopharyngeal aspirates from bacterial pneumonia patients. The assay presented with no cross-reactivity for 24 relevant bacterial species found in these types of samples. The limit of detection for serotyping and S. pneumoniae detection was 100 genome equivalent per reaction. Conclusion: This automated assay is amenable to clinical testing and does not require any culturing of the samples. The assay will be useful for the evaluation of serotype prevalence changes after new conjugate vaccines introduction. 166 quellung serotyped strains and two negative controls
Project description:Background Compelling evidence indicates that Shigella species, the etiologic agents of bacillary dysentery, as well as enteroinvasive Escherichia coli, are derived from multiple origins of Escherichia coli and form a single pathovar. To further understand the genome diversity and virulence evolution of Shigella, comparative genomic hybridization microarray analysis was employed to compare the gene content of E. coli K-12 with those of 43 Shigella strains from all serotypes. Results For the 43 strains subjected to CGH microarray analyses, the common backbone of the Shigella genome was estimated to contain more than 1,900 open reading frames, with a mean number of 729 undetectable ORFs. The mosaic distribution of absent regions indicated that insertions and/or deletions have led to the highly diversified genomes of pathogenic strains. Conclusion These results support the hypothesis that by gain and loss of functions, Shigella species became successful human pathogens through convergent evolution from diverse genomic backgrounds. Moreover, we also found many specific differences between different lineages, providing a window into understanding bacterial speciation and taxonomic relationships. Keywords: comparative genomic hybridization
Project description:Whole genome sequencing of cultured Shigella isolates to support the development of a serotyping pipeline using WGS for Shigella identification Raw sequence reads
Project description:to analyse the transcriptomic response of human intestinal tissue engrafted in SCID mice to Shigella infection Keywords: infection, Shigella, gene expression, intestinal cell
Project description:We evaluated the transcriptome changes induced by infection of Hela 229 cells with Shigella flexneri. The sample set consists of a control (mock), total population of infected sample and infected sample sorted into Shigella positive and Shigella negative population.
Project description:Trained immunity is a long-term memory of innate immune cells, generating an improved response upon re-infection. Shigella is an important human pathogen and inflammatory paradigm for which there is no effective vaccine. Using zebrafish larvae we demonstrate that after Shigella priming neutrophils are more efficient at bacterial clearance. We observe that Shigella-induced protection is non-specific and long-lasting, and is unlike training by BCG and β-glucan. Analysis of histone ChIP-seq on primed neutrophils revealed that Shigella training deposits the active H3K4me3 mark on promoter regions of 1612 genes, significantly changing the epigenetic landscape of neutrophils towards enhanced microbial recognition and mitochondrial ROS production. Finally, we demonstrate that mitochondrial ROS plays a key role in enhanced antimicrobial activity of trained neutrophils. It is envisioned that signals and mechanisms we discover here can be used in other vertebrates, including humans, to suggest new therapeutic strategies involving neutrophils to control bacterial infection.
Project description:To explore what important role of PhoPQ TCS plays in Shigella virulence, the Agilent microarray technologies was used to compare the transcriptional profiles of Shigella flexneri 2a 301 and △phoPQ mutant strains at middle-log phase (6 h) or early-stationary phase (10 h) under LB growth conditions.
Project description:In this study, we probed factors that could influence Shigella pathogenesis. We show that in basic pH conditions, deoxycholate-induced biofilm formation and virulence of Shigella are attenuated. We utilized RNA-sequencing to investigate pathways enriched in bacterial cells in biofilms.