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.
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: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:Global expression profiles of Salmonella typhi grown in the supernatant of infection and within human macrophages at 0h, 2h, 8h and 24h were obtained. Stringent analytical methods were used to compare Salmonella typhi cDNAs and revealed that known virulence factors, such as the SPI-1 and SPI-2 encoded type III secretion systems, were found to be expressed as predicted during infection by Salmonella. Intracellular Typhi expressed many genes encoding antimicrobial peptides, used the glyoxylate bypass for fatty acid utilization, and, did not induce the SOS response or the oxidative stress response. Genes coding for the flagellar apparatus, chemotaxis and the iron transport system were down-regulated in vivo. The combined use of SCOTS and microarray is an effective way to determine global bacterial gene expression profiling in the context of host infection, without the need of increasing the multiplicity of infection beyond what is seen in nature. Keywords: Time course
Project description:Sequencing of RNA of selected Salmonella Typhi strains from typhoid-endemic regions of Asia and Africahttp://www.sanger.ac.uk/resources/downloads/bacteria/salmonella.htmlThese data are part of a pre-publication release. For information on the proper use of pre-publication data shared by the Wellcome Trust Sanger Institute (including details of any publication moratoria), please see http://www.sanger.ac.uk/datasharing/
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.