title: Common genomic features of Campylobacter jejuni subsp. doylei strains distinguish them from C. jejuni subsp. jejuni.
abstract: BACKGROUND
  Campylobacter jejuni has been divided into two subspecies: C. jejuni subsp. jejuni (Cjj) and C. jejuni subsp. doylei (Cjd). Nearly all of the C. jejuni strains isolated are Cjj; nevertheless, although Cjd strains are isolated infrequently, they differ from Cjj in two key aspects: they are obtained primarily from human clinical samples and are associated often with bacteremia, in addition to gastroenteritis. In this study, we utilized multilocus sequence typing (MLST) and a DNA microarray-based comparative genomic indexing (CGI) approach to examine the genomic diversity and gene content of Cjd strains.
  
  
  RESULTS
  A geographically diverse collection of eight Cjd strains was examined by MLST and determined to be phylogenetically distinct from Cjj strains. Microarray-based CGI approach also supported this. We were able to demonstrate that Cjd strains exhibited divergence from Cjj strains NCTC 11168 and RM1221 in many of the intraspecies hypervariable regions. Moreover, multiple metabolic, transport and virulence functions (e.g. cytolethal distending toxin) were shown to be absent in the Cjd strains examined.
  
  
  CONCLUSIONS
  Our data demonstrate that Cjd are phylogenetically distinct from Cjj strains. Using the CGI approach, we identified subsets of absent genes from amongst the C. jejuni genes that provide clues as to the potential evolutionary origin and unusual pathogenicity of Cjd.
authors.affiliation: Produce Safety and Microbiology Research Unit, Agricultural Research Service, US. Department of Agriculture, Albany, CA 94710, USA. parker@pw.usda.gov
authors.forename: Craig T
authors.initials: CT
authors.lastname: Parker
authors.forename: William G
authors.initials: WG
authors.lastname: Miller
authors.forename: Sharon T
authors.initials: ST
authors.lastname: Horn
authors.forename: Albert J
authors.initials: AJ
authors.lastname: Lastovica
mesh_terms: D001692:Biological Transport / Q000235:genetics; D016123:Campylobacter jejuni / Q000145:classification* / Q000235:genetics*; D019143:Evolution, Molecular; D017353:Gene Deletion; D005798:Genes, Bacterial; D014644:Genetic Variation; D016680:Genome, Bacterial / Q000235:genetics*; D005838:Genotype; D006801:Humans; D053858:Metabolic Networks and Pathways / Q000235:genetics; D009693:Nucleic Acid Hybridization; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D037521:Virulence Factors / Q000235:genetics
chemical_list: D037521:Virulence Factors