Project description:Salmonella enterica subsp. enterica contains more than 2,600 serovars of which four are of major medical relevance for humans. While the typhoidal serovars (Typhi and Paratyphi A) are human-restricted and cause enteric fever, non-typhoidal Salmonella serovars (Typhimurium and Enteritidis) have a broad host range and predominantly cause gastroenteritis. In this study, we compared the core proteomes of Salmonella Typhi, Paratyphi A, Typhimurium and Enteritidis using contemporary proteomics. Five isolates, covering different geographical origins, and one reference strain per serovar were grown in vitro to the exponential phase. Protein levels of orthologous proteins between serovars were compared and subjected to gene ontology term enrichment and inferred regulatory interactions. Differential expression of the core proteomes of the typhoidal serovars appears mainly related to cell surface components and, for the non-typhoidal serovars, to pathogenicity. Our findings may guide future development of novel diagnostics and vaccines, and understanding of disease progression.
Project description:Human genetic diversity can reveal critical factors in host-pathogen interactions. This is especially useful for human-restricted pathogens like Salmonella enterica serovar Typhi (S. Typhi), the cause of Typhoid fever. One key dynamic during infection is competition for nutrients: host cells attempt to restrict intracellular replication by depriving bacteria of key nutrients or delivering toxic metabolites in a process called nutritional immunity. Here, a cellular genome-wide association study of intracellular replication by S. Typhi in nearly a thousand cell lines from around the world—and extensive follow-up using intracellular S. Typhi transcriptomics and manipulation of magnesium concentrations—demonstrates that the divalent cation channel mucolipin-2 (MCOLN2) restricts S. Typhi intracellular replication through magnesium deprivation. Our results reveal natural diversity in Mg2+ limitation as a key component of nutritional immunity against S. Typhi.
Project description:<p>Vaccine development against <i>Salmonella enterica</i> serovar Typhi (<i>S</i>. Typhi) requires a better understanding of interaction between human host and the resident microbial consortia in gastrointestinal tract. Healthy adult volunteers received either Ty21a, M01ZH09 or placebo, and underwent challenges with wt <i>S</i>. Typhi. Stool samples were collected at the screening interview (Baseline 1), prior to the first vaccination visit (Baseline 2), during vaccination (Day -28 and -26 for placebo and M01ZH09 groups; Day -32, -30, -28, -26 for Ty21a group), prior to challenge with <i>S</i>. Typhi (Day 0), and after challenge (day 0 12h, day 1, day 3, day 7, and day 10). 16S rRNA and messenger RNA were extracted from stool and sequenced on the Illumina Miseq and HiSeq 2000 platforms, respectively.</p>
Project description:Part of a study to characterise the two component regulatory system yehUT of Salmonella enterica serovar Salmonella Typhi and Typhimurium.
Project description:Salmonella enterica represent a major disease burden worldwide. While non-typhoidal Salmonella (NTS) serovars trigger self-limiting diarrhoea, leading to occasional secondary bacteraemia, S. enterica serovar Typhi is responsible for potentially life-threatening Typhoid fever. Dendritic cells (DCs) are key professional antigen presenting cells of the human immune system. The ability of pathogenic bacteria to subvert DC functions and prevent T cell recognition contributes to their survival and dissemination within the host. Here, we adapted Dual RNA-sequencing to define how different Salmonella pathovariants remodel their gene expression in tandem with that of infected DCs. We find DCs harness iron handling pathways to defend against invading Salmonellas, which, the human pathogen S. Typhi is able to circumvent. We show that S. Typhi mounts a robust response to host oxidative stress to avoid host iron-mediated defence mechanisms. In parallel, we provide evidence that invasive non-typhoidal Salmonella employs several strategies to impair DC functions and undertake alternative nutrient scavenging strategies to survive in the hostile intracellular environment.
Project description:Salmonella enterica serovar Typhi (S. Typhi), a human-restricted pathogen, enters the host through the gut to cause typhoid fever. Recent calculations of the typhoid fever burden estimated that more than 20 million new typhoid fever cases occur in low and middle-income countries, resulting in 129,000-223,000 deaths yearly. Interestingly, upon the resolution of acute disease, 1%-5% of patients become asymptomatic chronic carriers of S. Typhi. Chronically infected hosts are not only critical reservoirs of infection that transmit the disease to naive individuals but are also predisposed to developing gallbladder carcinoma (GBC). Nevertheless, the molecular mechanisms involved in the early interactions between gallbladder epithelial cells and S. Typhi remain largely unknown. Based on our previous studies showing that very closely related S. Typhi strains elicit distinct innate immune responses, we hypothesized that host molecular pathways activated by S. Typhi strains derived from acutely and chronically infected patients will differ. To test this hypothesis, we used a novel human organoid-derived polarized gallbladder monolayer (HODGM) model, and 13 S. Typhi strains derived from acutely (n=6) and chronically (n=7) infected patients. We found that S. Typhi strains derived from acutely and chronically infected patients differentially regulate mitogen-activated protein kinase (MAPK) and S6 transcription factors. This differential regulation impacts, at least in part, the cytokine signaling pathway involved in the production of TNF- and IL-6 and is likely to play a critical role in inducing chronic S. Typhi infection in the gallbladder.
Project description:Part of a study to characterise the two component regulatory system yehUT of Salmonella enterica serovar Salmonella Typhi and Typhimurium. 24 Samples examined, 12 of strain Salmonella Typhi BRD948 and 12 of strain Salmonella Typhimurium ST4/74.
Project description:Salmonella enterica is comprised of genetically distinct “serovars”, that together provide an intriguing model for exploring the genetic basis of pathogen evolution. While the genomes of numerous Salmonella isolates with broad variations in host range and human disease manifestations have been sequenced, the functional links between genetic and phenotypic differences among these serovars remain poorly understood. Here, we conduct high-throughput functional genomics on both generalist (Typhimurium) and human-restricted (Typhi & Paratyphi A) Salmonella at unprecedented scale in the study of this enteric pathogen. Using a comprehensive systems biology approach, we identify gene networks with serovar-specific fitness effects across 25 host-associated stresses encountered at key stages of human infection. By experimentally perturbing these networks, we characterize previously undescribed pseudogenes in human-adapted Salmonella. Overall, this work highlights specific vulnerabilities encoded within human-restricted Salmonella that are linked to the degradation of their genomes, shedding light into the evolution of this enteric pathogen.
Project description:The purpose of this experiment was to identify intestinal epithelial responses to various strains of Salmonella enterica. Human intestinal organoids were infected with three serovars of Salmonella; Typhimurium, Enteritidis and Typhi, as well as type 3 secretion system -1 and -2 mutants in Typhimurium in order to identify host responses that were similar and unique to each serovar, and responses that were dependent on these secretion systems.
Project description:In order to characterize pathogen specific T cell responses against Salmonella volunteers challenged with Salmonella enterica serovar Typhi (S. Typhi) or Salmonella Paratyphi A (S. Paratyphi). we used mass cytometry, to identify effector CD4+ T cells circulating during infection. We identified a population of CCR7-CD38+ cells accumulating during infection, and via unbiased single cell cloning and expansion we demonstrated that these CCR7-CD38+ cells are enriched in Salmonella specific T cells. In this experiment we performed TCR repertoire analysis of CCR7-CD38+ and CCR7-CD38- cells to determine the clonality of CCR7-CD38+ cells, the overlap between the repertoire of CCR7-CD38+ cells and of non-activated effector CCR7-CD38- cells, and to identify within CCR7-CD38+ and CCR7-CD38- cells the presence of the CDR3b TCR sequence of the pathogen specific T cell clones isolated from CCR7-CD38+ cells