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:Transcriptional profiling of three sequenced S. enterica strains: S. Typhimurium LT2, S. Typhi CT18, and S. Typhi Ty2 in PhoP-inducing and non-inducing conditions in vitro, and compared these results to profiles of phoP-/Q- mutants derived from S. Typhimurium LT2 and S. Typhi Ty2.
Project description:Macrophages provide a crucial environment for Salmonella enterica serovar Typhi (S. Typhi) to multiply during typhoid fever, yet our understanding of how human macrophages and S. Typhi interact remains limited. In this study, we delve into the dynamics of S. Typhi replication within human macrophages and the resulting heterogeneous transcriptomic responses of macrophages during infection. Our study reveals key factors that influence macrophage diversity, uncovering distinct immune and metabolic pathways associated with different stages of S. Typhi intracellular replication in macrophages. Of note, we found that macrophages harboring replicating S. Typhi are skewed towards an M1 pro-inflammatory state, whereas macrophages containing non-replicating S. Typhi exhibit neither a distinct M1 pro-inflammatory nor M2 anti-inflammatory state. Additionally, macrophages with replicating S. Typhi were characterized by the increased expression of genes associated with STAT3 phosphorylation and the activation of the STAT3 transcription factor. Our results shed light on transcriptomic pathways involved in the susceptibility of human macrophages to intracellular S. Typhi replication, thereby providing crucial insight into host phenotypes that restrict and support S. Typhi infection.
Project description:S. Typhi was cultured in broth, diluted and resuspended in water. RNA was prepared from the original broth culture (control), and from S. Typhi suspended in water for 0.5, 6 and 24 hours incubated at 28c without shaking
Project description:Six sequencing libraries was prepared from S. Typhi planktonic cells and biofilm cells using Illumina HiSeq 2500 sequencing to investigate differential gene expression between the two conditions. The transcriptome was processed using Cufflinks and there were a total of 35 up-regulated genes and 29 down-regulated genes log2-fold change values of greater than 2 and less than negative 2. The differentially expressed genes were identified using BLAST and the functions was analysed. This study provides an overview of the genes that are differentially expressed in S. Typhi when it transitions from the planktonic to the biofilm phenotype. The data will provide a basis for further study is necessary to uncover the mechanisms of biofilm formation in S. Typhi and discovery of novel gene functions or pathways associated with the development of the typhoid carrier state. This data may also be used to elucidate the effect of biofilm on the virulence and pathogenicity of S. Typhi in chronic carriers.
