title: Cytolethal distending toxin B gene (cdtB) homologues in taxa 2, 3 and 8 and in six canine isolates of Helicobacter sp. flexispira.
abstract: The presence of the cytolethal distending toxin B gene (cdtB) was examined in eight Helicobacter sp. flexispira reference strains, Helicobacter trogontum ATCC 700114(T) and 12 Finnish porcine H. trogontum strains and canine flexispira isolates. Part of the cdtB gene was amplified by PCR with degenerate primers VAT2 and DHF1, cloned and sequenced. The presence/absence of the cdtB gene as determined by PCR was confirmed by Southern hybridization and toxin production by HeLa cell-line experiments. PCR amplification resulted in approximately 700 bp fragments from Helicobacter sp. flexispira taxa 2 (ATCC 49314), 3 (ATCC 49320) and 8 (ATCC 43880, ATCC 49308, ATCC 43879), from six canine isolates as well as from the control strains Helicobacter bilis and Helicobacter hepaticus. The hybridization patterns of HaeIII-, HindIII- and AseI-digested chromosomal DNA confirmed the results of the PCR experiments. The cdtB-positive strains had effects ranging from weak to strong on HeLa cell cultures. PCR amplification from the reference strains Helicobacter sp. flexispira taxa 1 (ATCC 43968), 4 (ATCC 49310) and 5 (ATCC 43966) and H. trogontum (ATCC 700114(T)), and also six of the Finnish strains, was unsuccessful. No toxic effect on HeLa cells was evident when bacterial suspensions of PCR-negative strains were used for toxicity assay. Our results are in accordance with previous observations that the cdtB gene is not present in all Helicobacter species. Further, the presence/absence of the cdtB gene in Helicobacter sp. flexispira strains was in accordance with recent taxonomic analysis of the same strains, which suggests that it could serve as a useful marker in Helicobacter taxonomy.
authors.affiliation: Faculty of Veterinary Medicine, Department of Food and Environmental Hygiene, PO Box 57 (Hämeentie 57), 00014 University of Helsinki, Finland 2National Veterinary and Food Research Institute, Department of Virology, Hämeentie 57, 00580 Helsinki, Finland.
authors.forename: Silja
authors.initials: S
authors.lastname: Kostia
authors.affiliation: Faculty of Veterinary Medicine, Department of Food and Environmental Hygiene, PO Box 57 (Hämeentie 57), 00014 University of Helsinki, Finland 2National Veterinary and Food Research Institute, Department of Virology, Hämeentie 57, 00580 Helsinki, Finland.
authors.forename: Pirjo
authors.initials: P
authors.lastname: Veijalainen
authors.affiliation: Faculty of Veterinary Medicine, Department of Food and Environmental Hygiene, PO Box 57 (Hämeentie 57), 00014 University of Helsinki, Finland 2National Veterinary and Food Research Institute, Department of Virology, Hämeentie 57, 00580 Helsinki, Finland.
authors.forename: Urszula
authors.initials: U
authors.lastname: Hirvi
authors.affiliation: Faculty of Veterinary Medicine, Department of Food and Environmental Hygiene, PO Box 57 (Hämeentie 57), 00014 University of Helsinki, Finland 2National Veterinary and Food Research Institute, Department of Virology, Hämeentie 57, 00580 Helsinki, Finland.
authors.forename: Marja-Liisa
authors.initials: ML
authors.lastname: Hänninen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001427:Bacterial Toxins / Q000737:chemistry / Q000235:genetics* / Q000633:toxicity; D001483:Base Sequence; D015139:Blotting, Southern; D004269:DNA, Bacterial / Q000737:chemistry; D004285:Dogs; D005784:Gene Amplification; D006367:HeLa Cells; D016998:Helicobacter / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D010446:Peptide Fragments; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D051381:Rats; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012756:Sheep; D013552:Swine
chemical_list: D001427:Bacterial Toxins; D004269:DNA, Bacterial; D010446:Peptide Fragments; C067044:cytolethal distending toxin