Project description:Many clinically relevant bacterial pathogens are encapsulated, as exemplified by Salmonella enterica serovar Typhi. S. Typhi, the causative agent of the life-threatening systemic disease enteric fever, expresses Vi as the outermost surface glycan that protects the bacteria from host immune responses. Multidrug-resistant (MDR) and extensively drug-resistant (XDR) S. Typhi strains, as well as Vi variants, are widespread globally. Our WGS analyses indicate that almost all S. Typhi clinical isolates are susceptible to rifamycins and azithromycin. Rifampin, even at sub-MIC levels, eliminates the protective capsule Vi, a process referred to as ‘decapsulation’, thereby enhancing bacterial clearance. Antibiotic-mediated decapsulation of S. Typhi appears specific to rifamycins, since azithromycin does not decapsulate S. Typhi. Rifampin mediated decapsulation occurs at the transcriptional level, where both high AT content and specific RpoB residues play a crucial role. Rifampin also effectively decapsulates Vi variants, which accounts for 1 in 5 S. Typhi isolates at the global level. A mechanistic explanation for rifampin mediated decapsulation of S. Typhi appears to be applicable to other encapsulated pathogens, including S. Paratyphi C.
2025-05-15 | GSE295448 | GEO
Project description:Whole-genome sequencing of XDR strains of S. Typhi
Project description:Extensively drug resistant tuberculosis (XDR-TB) showed many different characteristics including the extreme drug resistance versus the drug sensitive clinical isolates (DS-TB), to know better about the reasons we used the tuberculosis host cells named as THP-1 (one kind of the macrophage cells) to be infected by the XDR-TB and DS-TB.DS strain A36 and the XDR strain B42 and was typical and selected by our lab. Then the total RNA of infected or uninfected THP-1 cells was extract and purified for the analysis by the chip (22K Human Genome chip representing the 21522 ORF of human with the oligonucleotide probe of 70 mer from CapitalBio Corp., Beijing, China). The results reflected the different expressed genes involved in apoptosis, secreted cytokines and signal pathway and so on. Those results might indicate the how the XDR-TB cause the pathogenesis.
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: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.