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An oligopeptide permease is postulated to be a virulence factor in Borrelia burgdorferi. Genes perceived to code for this protein were identified and characterized. A total of five genes, three chromosomal genes and two plasmid genes were identified. Northern blot studies revealed that each gene is transcribed independently of the others and that transcription is initiated with temperature change in one of the plasmid genes.

Lysyl-tRNAs are essential for protein biosynthesis by ribosomal mRNA translation in all organisms. They are synthesized by lysyl-tRNA synthetases (EC 6.1.1.6), a group of enzymes composed of two unrelated families. In bacteria and eukarya, all known lysyl-tRNA synthetases are subclass IIc-type aminoacyl-tRNA synthetases, whereas some archaea have been shown to contain an unrelated class I-type lysyl-tRNA synthetase. Examination of the preliminary genomic sequence of the bacterial pathogen Borrelia burgdorferi, the causative agent of Lyme disease, indicated the presence of an open reading frame with over 55% similarity at the amino acid level to archaeal class I-type lysyl-tRNA synthetases. In contrast, no coding region with significant similarity to any class II-type lysyl-tRNA synthetase could be detected. Heterologous expression of this open reading frame in Escherichia coli led to the production of a protein with canonical lysyl-tRNA synthetase activity in vitro. Analysis of B. burgdorferi mRNA showed that the lysyl-tRNA synthetase-encoding gene is highly expressed, confirming that B. burgdorferi contains a functional class I-type lysyl-tRNA synthetase. The detection of an archaeal-type lysyl-tRNA synthetase in B. burgdorferi and other pathogenic spirochetes, but not to date elsewhere in bacteria or eukarya, indicates that the gene that encodes this enzyme has a common origin with its orthologue from the archaeal kingdom. This difference between the lysyl-tRNA synthetases of spirochetes and their hosts may be readily exploitable for the development of anti-spirochete therapeutics.

The mapping of the genes encoding the antigenic lipoproteins OspE and OspF to an approximately 18-kb circular plasmid in Borrelia burgdorferi N40 is discussed. It is shown that the plasmid cp18 is homologous to an 18-kb region of the cp32 circular plasmids found in the Lyme disease spirochetes. It is also shown that cp18 could arise from an ancestral cp32 plasmic by deletion of a 14-kb region of DNA.

Abstract Background Emerging molecular, animal model and epidemiologic evidence suggests that Shiga-toxigenic Escherichia coli O157:H7 (STEC O157) isolates vary in their capacity to cause human infection and disease. The translocated intimin receptor (tir) and intimin (eae) are virulence factors and bacterial receptor-ligand proteins responsible for tight STEC O157 adherence to intestinal epithelial cells. They represent logical genomic targets to investigate the role of sequence variation in STEC O157 pathogenesis and molecular epidemiology. The purposes of this study were (1) to identify tir and eae polymorphisms in diverse STEC O157 isolates derived from clinically ill humans and healthy cattle (the dominant zoonotic reservoir) and (2) to test any observed tir and eae polymorphisms for association with human (vs bovine) isolate source. Results Five polymorphisms were identified in a 1,627-bp segment of tir. Alleles of two tir polymorphisms, tir 255 T>A and repeat region 1-repeat unit 3 (RR1-RU3, presence or absence) had dissimilar distributions among human and bovine isolates. More than 99% of 108 human isolates possessed the tir 255 T>A T allele and lacked RR1-RU3. In contrast, the tir 255 T>A T allele and RR1-RU3 absence were found in 55% and 57%, respectively, of 77 bovine isolates. Both polymorphisms associated strongly with isolate source (p < 0.0001), but not by pulsed field gel electrophoresis type or by stx1 and stx2 status (as determined by PCR). Two eae polymorphisms were identified in a 2,755-bp segment of 44 human and bovine isolates; 42 isolates had identical eae sequences. The eae polymorphisms did not associate with isolate source. Conclusion Polymorphisms in tir but not eae predict the propensity of STEC O157 isolates to cause human clinical disease. The over-representation of the tir 255 T>A T allele in human-derived isolates vs the tir 255 T>A A allele suggests that these isolates have a higher propensity to cause disease. The high frequency of bovine isolates with the A allele suggests a possible bovine ecological niche for this STEC O157 subset.

Arcobacter species are recovered from a wide variety of sources, including animals, food, and both fresh and marine waters. Several Arcobacter species have also been recovered from human clinical samples and are thus associated tentatively with food- and water-borne human illnesses. Genome sequencing of the poultry isolate Arcobacter cibarius H743 and the Arcobacter acticola , Arcobacter pacificus , and Arcobacter porcinus type strains identified a large number and variety of insertion sequences. This study presents an analysis of these A. acticola , A. cibarius , A. pacificus , and A. porcinus IS elements. The four genomes sequenced here contain 276 complete and degenerate IS elements, representing 13 of the current 29 prokaryotic IS element families. Expansion of the analysis to include 15 other previously sequenced Arcobacter spp. added 73 complete and degenerate IS elements. Several of these IS elements were identified in two or more Arcobacter species, suggesting movement by horizontal gene transfer between the arcobacters. These IS elements are putatively associated with intragenomic deletions and inversions, and tentative movement of antimicrobial resistance genes. The A. cibarius strain H743 megaplasmid contains multiple IS elements common to the chromosome and, unusually, a complete ribosomal RNA locus, indicating that larger scale genomic rearrangements, potentially resulting from IS element-mediated megaplasmid cointegration and resolution may be occurring within A. cibarius and possibly other arcobacters. The presence of such a large and varied suite of mobile elements could have profound effects on Arcobacter biology and evolution. [ABSTRACT FROM AUTHOR]

Shiga-toxigenic Escherichia coli (STEC) O157 occurrence is determined along the entire gastrointestinal tract (GIT) of each of four naturally shedding cattle and at three sites in slaughter cattle. The studies have shown that there is high animal-to-animal variability in the location of STEC O157 in the GIT and that the small intestine might support STEC O157 colonization.

The full-length sequencing survey of 11,171 16S rRNA genes of the intestinal microbiota of beef cattle which are important for animal health, food safety and methane emissions is reported. The results revealed that animal-to-animal variation in communities that could no be attributed to breed, gender, diet, age or weather and beef communities differ from those of dairy.

The enterohemorrhagic Escherichia coli serotypes O157:H7 and O157:H (EHEC-O157) isolates obtained from cattle are gentotyped to determine if the proportion of EHEC-O157 genotypes in the bovine reservoirs influenced the rates of the diverse international incidence of EHEC-O157 disease. The proportion of clinical genotypes among cattle isolates are weakly related to the international incidence of EHEC-O157-associated hemolytic-uremic syndrome, differed among clinical isolates internationally and along the putative cattle-hamburger-clinical case transmission chain.

A study was conducted to characterize the bacteriophage insertion site genotype of Escherichia coli O157:H7 isolates from cattle and from humans and found increased genotype diversity among bovine isolates and differential representation of genotypes in these host species.

A molecular serotyping protocol was developed to target the somatic and flagellar antigens of Escherichia coli O26:H11 used in traditional serotyping. It is concluded that Escherichia coli O26:H11 accurately determined O26 and H11 serotypes strains by traditional methods thus, affording primary laboratories serotyping capabilities.

A commercially available real-time, rapid PCR test is evaluated for its ability to detect Escherichia coli O157. Both the sensitivity and specificity of the assay were 99% for isolates in pure culture.

Background Shiga toxin–producing Escherchia coli (STEC) O157:H7 is a zoonotic pathogen that causes numerous food and waterborne disease outbreaks. It is globally distributed, but its origin and the temporal sequence of its geographical spread are unknown. Methods We analyzed whole-genome sequencing data of 757 isolates from 4 continents, and performed a pan-genome analysis to identify the core genome and, from this, extracted single-nucleotide polymorphisms. A timed phylogeographic analysis was performed on a subset of the isolates to investigate its worldwide spread. Results The common ancestor of this set of isolates occurred around 1890 (1845–1925) and originated from the Netherlands. Phylogeographic analysis identified 34 major transmission events. The earliest were predominantly intercontinental, moving from Europe to Australia around 1937 (1909–1958), to the United States in 1941 (1921–1962), to Canada in 1960 (1943–1979), and from Australia to New Zealand in 1966 (1943–1982). This pre-dates the first reported human case of E. coli O157:H7, which was in 1975 from the United States. Conclusions Inter- and intra-continental transmission events have resulted in the current international distribution of E. coli O157:H7, and it is likely that these events were facilitated by animal movements (eg, Holstein Friesian cattle). These findings will inform policy on action that is crucial to reduce the further spread of E. coli O157:H7 and other (emerging) STEC strains globally. [ABSTRACT FROM AUTHOR]