Project description:Forty-two Helicobacter isolates were isolated from swine feces in The Netherlands and Denmark. All 12 isolates sequenced (16S rRNA gene) formed a robust clade with Helicobacter canadensis ( approximately 99% similarity). Species-specific PCR indicated that all of the isolates were H. canadensis isolates. Although the appearance of the porcine isolates was similar to the appearance of H. canadensis, only one of these isolates was able to hydrolyze indoxyl acetate, a cardinal characteristic of this taxon. Examination of the 23S rRNA and hsp60 genes revealed high levels of similarity between the porcine isolates and H. canadensis. However, amplified fragment length polymorphism genomic typing showed that isolates recovered from swine feces were genetically distinct from H. canadensis strains obtained from humans and geese.
Project description:We determined the genome sequence of the type strain of Helicobacter canadensis, an emerging human pathogen with diverse animal reservoirs. Potential virulence determinants carried by the genome include systems for N-linked glycosylation and capsular export. A protein-based phylogenetic analysis places H. canadensis close to Wolinella succinogenes.
Project description:Sexual reproduction and recombination are essential for the survival of most eukaryotic populations. Until recently, the impact of these processes on the structure of bacterial populations has been largely overlooked. The advent of large-scale whole-genome sequencing and the concomitant development of molecular tools, such as microarray technology, facilitate the sensitive detection of recombination events in bacteria. These techniques are revealing that bacterial populations are comprised of isolates that show a surprisingly wide spectrum of genetic diversity at the DNA level. Our new awareness of this genetic diversity is increasing our understanding of population structures and of how these affect host?pathogen relationships. Set of arrays organized by shared biological context, such as organism, tumors types, processes, etc. Keywords: Logical Set
Project description:We recently analyzed 11 helicobacter isolates cultured from diarrhea patients in Canada. These isolates had been characterized biochemically by restriction fragment length polymorphism (RFLP; AluI, HhaI) analysis and by fatty-acid analysis as Helicobacter pullorum. However, four of the isolates differed biochemically from H. pullorum by their inability to hydrolyze indoxyl acetate and their resistance to nalidixic acid. Using complete 16S rRNA analysis, we determined that these four strains clustered near H. pullorum but had a sequence difference of 2% and therefore represent a novel helicobacter, Helicobacter canadensis. This novel helicobacter could also be distinguished from H. pullorum by RFLP analysis using ApaLI. The number of novel Helicobacter spp. associated with gastrointestinal disease in humans and animals is rapidly increasing. There are now six Helicobacter spp. isolated from diarrheic humans, the other five being H. pullorum, H. canis, "H. rappini," H. fennelliae, and H. cinaedi. This finding highlights the importance of careful molecular analysis in addition to standard biochemical tests in identifying the increasing number of Helicobacter spp. isolated from humans and animals.
Project description:The goal of this study is to utilize dual host-pathogen NGS to assess transcriptomic pertubations due to multiple drug compounds, and compare between compounds to identify putative mechanism of action for novel anti-Rickettsial compounds.
Project description:BackgroundHelicobacter canadensis is an emerging human pathogen and zoonotic agent. The genome of H. canadensis was sequenced previously and determined to contain 29 annotated coding regions associated with homopolymeric tracts.ResultsTwenty-one of the repeat-associated coding regions were determined to be potentially transcriptionally or translationally phase variable. In each case the homopolymeric tract was within the predicted promoter region or at the 5' end of the coding region, respectively. However, eight coding sequences were identified with simple sequence repeats toward the 3' end of the open reading frame. In these cases, the repeat tract would be too far into the coding region to be mediating translational phase variation. All of the 29 coding region-associated homopolymeric tracts display variability in tract length in the sequencing read data.ConclusionsTwenty-nine coding regions have been identified in the genome sequence of Helicobacter canadensis strain NCTC13241 that show variations in homopolymeric tract length in the bacterial population, indicative of phase variation. Five of these are potentially associated with promoter regions, which would lead to transcriptional phase variation. Translational phase variation usually switches expression of a gene ON and OFF due to the repeat region being located sufficiently close to the initiation codon for the resulting frame-shift to lead to a premature termination codon and stop the translation of the protein. Sixteen of the 29 coding regions have homopolymeric tracts characteristic of translational phase variation. For eight coding sequences with repeats located later in the reading frame, changes in the repeat tract length would alter the protein sequence at the C-terminus but not stop the expression of the protein. This mechanism of C-terminal phase variation has implications for stochastic switching of protein sequence in bacterial species that already undergo transcriptional and translational phase variation.