scholarly journals Salmonella enterica Serovar Typhi Possesses a Unique Repertoire of Fimbrial Gene Sequences

2001 ◽  
Vol 69 (5) ◽  
pp. 2894-2901 ◽  
Author(s):  
Stacy M. Townsend ◽  
Naomi E. Kramer ◽  
Robert Edwards ◽  
Stephen Baker ◽  
Nancy Hamlin ◽  
...  
Keyword(s):  
Host Range ◽  
Salmonella Enterica ◽  
Host Adaptation ◽  
Unique Combination ◽  
Gene Sequences ◽  
Simple Correlation ◽  
Salmonella Enterica Serovar Typhi ◽  
Type Iv ◽  
Reference Collection ◽  
First Time

ABSTRACT Salmonella enterica serotype Typhi differs from nontyphoidal Salmonella serotypes by its strict host adaptation to humans and higher primates. Since fimbriae have been implicated in host adaptation, we investigated whether the serotype Typhi genome contains fimbrial operons which are unique to this pathogen or restricted to typhoidal Salmonella serotypes. This study established for the first time the total number of fimbrial operons present in an individual Salmonella serotype. The serotype Typhi CT18 genome, which has been sequenced by the Typhi Sequencing Group at the Sanger Centre, contained a type IV fimbrial operon, an orthologue of the agf operon, and 12 putative fimbrial operons of the chaperone-usher assembly class. In addition tosef, fim, saf, and tcf, which had been described previously in serotype Typhi, we identified eight new putative chaperone-usher-dependent fimbrial operons, which were termedbcf, sta, stb, ste, std, stc, stg, and sth. Hybridization analysis performed with 16 strains ofSalmonella reference collection C and 22 strains ofSalmonella reference collection B showed that all eight putative fimbrial operons of serotype Typhi were also present in a number of nontyphoidal Salmonella serotypes. Thus, a simple correlation between host range and the presence of a single fimbrial operon seems at present unlikely. However, the serotype Typhi genome differed from that of all other Salmonella serotypes investigated in that it contained a unique combination of putative fimbrial operons.

scholarly journals Machine learning identifies signatures of host adaptation in the bacterial pathogen Salmonella enterica

2017 ◽  
Author(s):  
Nicole E. Wheeler ◽  
Paul P. Gardner ◽  
Lars Barquist
Keyword(s):  
Random Forest ◽  
Host Range ◽  
Salmonella Enterica ◽  
Bacterial Pathogen ◽  
Host Adaptation ◽  
Random Forest Classifier ◽  
Sub Saharan Africa ◽  
Broad Host Range ◽  
Invasive Infection ◽  
Emerging Pathogens

AbstractEmerging pathogens are a major threat to public health, however understanding how pathogens adapt to new niches remains a challenge. New methods are urgently required to provide functional insights into pathogens from the massive genomic data sets now being generated from routine pathogen surveillance for epidemiological purposes. Here, we measure the burden of atypical mutations in protein coding genes across independently evolved Salmonella enterica lineages, and use these as input to train a random forest classifier to identify strains associated with extraintestinal disease. Members of the species fall along a continuum, from pathovars which cause gastrointestinal infection and low mortality, associated with a broad host-range, to those that cause invasive infection and high mortality, associated with a narrowed host range. Our random forest classifier learned to perfectly discriminate long-established gastrointestinal and invasive serovars of Salmonella. Additionally, it was able to discriminate recently emerged Salmonella Enteritidis and Typhimurium lineages associated with invasive disease in immunocompromised populations in sub-Saharan Africa, and within-host adaptation to invasive infection. We dissect the architecture of the model to identify the genes that were most informative of phenotype, revealing a common theme of degradation of metabolic pathways in extraintestinal lineages. This approach accurately identifies patterns of gene degradation and diversifying selection specific to invasive serovars that have been captured by more labour-intensive investigations, but can be readily scaled to larger analyses.

scholarly journals Linear plasmids and their replication

2013 ◽  
Vol 2 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Sunjukta Ahsan ◽  
Md Shahidul Kabir
Keyword(s):  
Causative Agent ◽  
Salmonella Enterica ◽  
The Other ◽  
Linear Plasmid ◽  
Covalent Attachment ◽  
Common Belief ◽  
Replication Machinery ◽  
Linear Plasmids ◽  
Salmonella Enterica Serovar Typhi ◽  
First Time

It is still a common belief that plasmids are circular. However, linear plasmids have been reported to exist more than a decade ago. Two types of linear plasmids are known. One type contains covalently closed ends and are commonly found in Borrelia, the causative agent of tick fever. The other type is characterized by the covalent attachment of proteins at the 5' ends and exists in a number of bacterial genera including Streptomyces, Rhodococcus, Mycobacterium and Planobispora. Recently, a linear plasmid in Salmonella enterica serovar Typhi of the Enterobacteriaceae family have been reported for the first time. This paper reviews various postulated mechanisms of replication of linear plasmids and focuses on the components of the replication machinery of linear plasmids studied to date. DOI: http://dx.doi.org/10.3329/sjm.v2i1.15200 Stamford Journal of Microbiology, Vol.2(1) 2012: 1-5

scholarly journals Cooperation of Adhesin Alleles in Salmonella-Host Tropism

mSphere ◽  
2017 ◽  
Vol 2 (2) ◽  
Author(s):  
Leon De Masi ◽  
Min Yue ◽  
Changmin Hu ◽  
Alexey V. Rakov ◽  
Shelley C. Rankin ◽  
...  
Keyword(s):  
Host Range ◽  
Salmonella Enterica ◽  
Bacterial Pathogen ◽  
The United States ◽  
Host Adaptation ◽  
Broad Host Range ◽  
Intestinal Epithelial ◽  
Content Type ◽  
Contaminated Food ◽  
Colonization Factors

ABSTRACT Salmonella enterica remains a leading foodborne bacterial pathogen in the United States; infected livestock serve often as the source of contaminated food products. A study estimated that over a billion Salmonella gastroenteritis cases and up to 33 million typhoid cases occur annually worldwide, with 3.5 million deaths. Although many Salmonella strains with a broad host range present preferential associations with certain host species, it is not clear what determines the various levels of host adaptation. Here, causal properties of host associations were determined with allelic variants of three colonization factors of S. enterica serovar Newport, a most frequent zoonotic serovar. This is the first study that related not only individual but also a small group of host-associated gene variants with functional properties that cooperate to determine the level of host-adapted virulence. The detected associations should help to identify sources of Salmonella infections in both humans and animals. Allelic combinations and host specificities for three fimbrial adhesins, FimH, BcfD, and StfH, were compared for 262 strains of Salmonella enterica serovar Newport, a frequent human and livestock pathogen. Like FimH, BcfD had two major alleles (designated A and B), whereas StfH had two allelic groups, each with two alleles (subgroup A1 and A2 and subgroup B1 and B2). The most prevalent combinations of FimH/BcfD/StfH alleles in S. Newport were A/A/A1 and B/B/B1. The former set was most frequently found in bovine and porcine strains, whereas the latter combination was most frequently found in environmental and human isolates. Bacteria genetically engineered to express Fim, Bcf, or Stf fimbriae on their surface were tested with the different alleles for binding to human, porcine, and bovine intestinal epithelial cells. The major allelic combinations with bovine and porcine strains (A/A/A1) or with human isolates (B/B/B1) provided at least two alleles capable of binding significantly better than the other alleles to an intestinal epithelial cell line from the respective host(s). However, each combination of alleles kept at least one allele mediating binding to an intestinal epithelial cell from another host. These findings indicated that allelic variation in multiple adhesins of S. Newport contributes to bacterial adaptation to certain preferential hosts without losing the capacity to maintain a broad host range. IMPORTANCE Salmonella enterica remains a leading foodborne bacterial pathogen in the United States; infected livestock serve often as the source of contaminated food products. A study estimated that over a billion Salmonella gastroenteritis cases and up to 33 million typhoid cases occur annually worldwide, with 3.5 million deaths. Although many Salmonella strains with a broad host range present preferential associations with certain host species, it is not clear what determines the various levels of host adaptation. Here, causal properties of host associations were determined with allelic variants of three colonization factors of S. enterica serovar Newport, a most frequent zoonotic serovar. This is the first study that related not only individual but also a small group of host-associated gene variants with functional properties that cooperate to determine the level of host-adapted virulence. The detected associations should help to identify sources of Salmonella infections in both humans and animals.

scholarly journals Genomic Comparison of Salmonella enterica Serovars and Salmonella bongori by Use of an S. enterica Serovar Typhimurium DNA Microarray

2003 ◽  
Vol 185 (2) ◽  
pp. 553-563 ◽  
Author(s):  
Kaman Chan ◽  
Stephen Baker ◽  
Charles C. Kim ◽  
Corrella S. Detweiler ◽  
Gordon Dougan ◽  
...  
Keyword(s):  
Host Range ◽  
Dna Microarray ◽  
Salmonella Enterica ◽  
Genetic Relatedness ◽  
Host Adaptation ◽  
Enzyme Electrophoresis ◽  
Genomic Changes ◽  
Serovar Typhimurium ◽  
Taxonomic Organization ◽  
Insight Into

ABSTRACT The genus Salmonella consists of over 2,200 serovars that differ in their host range and ability to cause disease despite their close genetic relatedness. The genetic factors that influence each serovar's level of host adaptation, how they evolved or were acquired, their influence on the evolution of each serovar, and the phylogenic relationships between the serovars are of great interest as they provide insight into the mechanisms behind these differences in host range and disease progression. We have used an Salmonella enterica serovar Typhimurium spotted DNA microarray to perform genomic hybridizations of various serovars and strains of both S. enterica (subspecies I and IIIa) and Salmonella bongori to gain insight into the genetic organization of the serovars. Our results are generally consistent with previously published DNA association and multilocus enzyme electrophoresis data. Our findings also reveal novel information. We observe a more distant relationship of serovar Arizona (subspecies IIIa) from the subspecies I serovars than previously measured. We also observe variability in the Arizona SPI-2 pathogenicity island, indicating that it has evolved in a manner distinct from the other serovars. In addition, we identify shared genetic features of S. enterica serovars Typhi, Paratyphi A, and Sendai that parallel their unique ability to cause enteric fever in humans. Therefore, whereas the taxonomic organization of Salmonella into serogroups provides a good first approximation of genetic relatedness, we show that it does not account for genomic changes that contribute to a serovar's degree of host adaptation.

scholarly journals B Cells Control Mucosal-Associated Invariant T Cell Responses to Salmonella enterica Serovar Typhi Infection Through the CD85j HLA-G Receptor

2021 ◽  
Vol 12 ◽  
Author(s):  
Rosângela Salerno-Gonçalves ◽  
Tasmia Rezwan ◽  
David Luo ◽  
Hervé Tettelin ◽  
Marcelo B. Sztein
Keyword(s):  
B Cells ◽  
Salmonella Enterica ◽  
Kinetic Studies ◽  
Salmonella Enterica Serovar Typhi ◽  
Mait Cells ◽  
Cell Responses ◽  
Ifn Γ ◽  
And Function ◽  
First Time ◽  
Mait Cell

Mucosal-associated invariant T (MAIT) cells are an innate-like population of T cells that display a TCR Vα7.2+ CD161+ phenotype and are restricted by the nonclassical MHC-related molecule 1 (MR1). Although B cells control MAIT cell development and function, little is known about the mechanisms underlying their interaction(s). Here, we report, for the first time, that during Salmonella enterica serovar Typhi (S. Typhi) infection, HLA-G expression on B cells downregulates IFN-γ production by MAIT cells. In contrast, blocking HLA-G expression on S. Typhi-infected B cells increases IFN-γ production by MAIT cells. After interacting with MAIT cells, kinetic studies show that B cells upregulate HLA-G expression and downregulate the inhibitory HLA-G receptor CD85j on MAIT cells resulting in their loss. These results provide a new role for HLA-G as a negative feedback loop by which B cells control MAIT cell responses to antigens.

scholarly journals A genomic snapshot of Salmonella enterica serovar Typhi in Colombia

2021 ◽  
Vol 15 (9) ◽  
pp. e0009755
Author(s):  
Paula Diaz Guevara ◽  
Mailis Maes ◽  
Duy Pham Thanh ◽  
Carolina Duarte ◽  
Edna Catering Rodriguez ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Latin America ◽  
Latin American ◽  
Salmonella Enterica ◽  
Disease Burden ◽  
Pulse Field ◽  
Small Subset ◽  
Salmonella Enterica Serovar Typhi ◽  
Pulse Field Gel Electrophoresis ◽  
First Time

Little is known about the genetic diversity of Salmonella enterica serovar Typhi (S. Typhi) circulating in Latin America. It has been observed that typhoid fever is still endemic in this part of the world; however, a lack of standardized blood culture surveillance across Latin American makes estimating the true disease burden problematic. The Colombian National Health Service established a surveillance system for tracking bacterial pathogens, including S. Typhi, in 2006. Here, we characterized 77 representative Colombian S. Typhi isolates collected between 1997 and 2018 using pulse field gel electrophoresis (PFGE; the accepted genotyping method in Latin America) and whole genome sequencing (WGS). We found that the main S. Typhi clades circulating in Colombia were clades 2.5 and 3.5. Notably, the sequenced S. Typhi isolates from Colombia were closely related in a global phylogeny. Consequently, these data suggest that these are endemic clades circulating in Colombia. We found that AMR in S. Typhi in Colombia was uncommon, with a small subset of organisms exhibiting mutations associated with reduced susceptibility to fluoroquinolones. This is the first time that S. Typhi isolated from Colombia have been characterized by WGS, and after comparing these data with those generated using PFGE, we conclude that PFGE is unsuitable for tracking S. Typhi clones and mapping transmission. The genetic diversity of pathogens such as S. Typhi is limited in Latin America and should be targeted for future surveillance studies incorporating WGS.

scholarly journals Integrative Taxonomy and Molecular Phylogeny of the Plant-Parasitic Nematode Genus Paratylenchus (Nematoda: Paratylenchinae): Linking Species with Molecular Barcodes

Plants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 408
Author(s):  
Phougeishangbam Rolish Singh ◽  
Gerrit Karssen ◽  
Marjolein Couvreur ◽  
Sergei A. Subbotin ◽  
Wim Bert
Keyword(s):  
18S Rrna ◽  
Parasitic Nematode ◽  
Integrative Taxonomy ◽  
Coi Gene ◽  
Integrated Analysis ◽  
Gene Sequences ◽  
Unknown Species ◽  
New Gene ◽  
First Time ◽  
Plant Parasitic

Pin nematodes of the genus Paratylenchus are obligate ectoparasites of a wide variety of plants that are distributed worldwide. In this study, individual morphologically vouchered nematode specimens of fourteen Paratylenchus species, including P. aculentus, P. elachistus, P. goodeyi, P. holdemani, P. idalimus, P. microdorus, P. nanus, P. neoamblycephalus, P. straeleni and P. veruculatus, are unequivocally linked to the D2-D3 of 28S, ITS, 18S rRNA and COI gene sequences. Combined with scanning electron microscopy and a molecular analysis of an additional nine known and thirteen unknown species originating from diverse geographic regions, a total of 92 D2-D3 of 28S, 41 ITS, 57 18S rRNA and 111 COI new gene sequences are presented. Paratylenchus elachistus, P. holdemani and P. neoamblycephalus are recorded for the first time in Belgium and P. idalimus for the first time in Europe. Paratylenchus is an excellent example of an incredibly diverse yet morphologically minimalistic plant-parasitic genus, and this study provides an integrated analysis of all available data, including coalescence-based molecular species delimitation, resulting in an updated Paratylenchus phylogeny and the corrective reassignment of 18 D2-D3 of 28S, 3 ITS, 3 18S rRNA and 25 COI gene sequences that were previously unidentified or incorrectly classified.

Sign in / Sign up

Export Citation Format

Share Document