title: Analysis and comparative genomics of ICEMh1, a novel integrative and conjugative element (ICE) of Mannheimia haemolytica.
abstract: OBJECTIVE
  The aim of this study was to identify and analyse the first integrative and conjugative element (ICE) from Mannheimia haemolytica, the major bacterial component of the bovine respiratory disease (BRD) complex.
  
  
  METHODS
  The novel ICEMh1 was discovered in the whole-genome sequence of M. haemolytica 42548 by sequence analysis and comparative genomics. Transfer of ICEMh1 was confirmed by conjugation into Pasteurella multocida recipient cells.
  
  
  RESULTS
  ICEMh1 has a size of 92,345 bp and harbours 107 genes. It integrates into a chromosomal tRNA(Leu) copy. Within two resistance gene regions of ∼ 7.4 and 3.3 kb, ICEMh1 harbours five genes, which confer resistance to streptomycin (strA and strB), kanamycin/neomycin (aphA1), tetracycline [tetR-tet(H)] and sulphonamides (sul2). ICEMh1 is related to the recently described ICEPmu1 and both ICEs seem to have evolved from a common ancestor. A region of ICEMh1 that is absent in ICEPmu1 was found in putative ICE regions of other M. haemolytica genomes, suggesting a recombination event between two ICEs. ICEMh1 transfers to P. multocida by conjugation, in which it also uses a tRNA(Leu) as the integration site. PCR assays and susceptibility testing confirmed the presence and activity of the ICEMh1-associated resistance genes in the P. multocida recipient.
  
  
  CONCLUSIONS
  These findings showed that ICEs, with structurally variable resistance gene regions, are present in BRD-associated Pasteurellaceae, can easily spread across genus borders and enable the acquisition of multidrug resistance via a single horizontal gene transfer event. This poses a threat to efficient antimicrobial chemotherapy of BRD-associated bacterial pathogens.
authors.affiliation: Institute of Farm Animal Genetics, Friedrich-Loeffler-Institut (FLI), Neustadt-Mariensee, Germany.
authors.forename: Christopher
authors.initials: C
authors.lastname: Eidam
authors.affiliation: Department of Genomic and Applied Microbiology, Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg August University of Göttingen, Göttingen, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Poehlein
authors.affiliation: Department of Genomic and Applied Microbiology, Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg August University of Göttingen, Göttingen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Leimbach
authors.affiliation: Institute of Farm Animal Genetics, Friedrich-Loeffler-Institut (FLI), Neustadt-Mariensee, Germany.
authors.forename: Geovana Brenner
authors.initials: GB
authors.lastname: Michael
authors.affiliation: Institute of Farm Animal Genetics, Friedrich-Loeffler-Institut (FLI), Neustadt-Mariensee, Germany.
authors.forename: Kristina
authors.initials: K
authors.lastname: Kadlec
authors.affiliation: Department of Genomic and Applied Microbiology, Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg August University of Göttingen, Göttingen, Germany.
authors.forename: Heiko
authors.initials: H
authors.lastname: Liesegang
authors.affiliation: Department of Genomic and Applied Microbiology, Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg August University of Göttingen, Göttingen, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Daniel
authors.affiliation: Zoetis, Kalamazoo, MI, USA.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Sweeney
authors.affiliation: Zoetis, Kalamazoo, MI, USA.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Murray
authors.affiliation: Zoetis, Kalamazoo, MI, USA.
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Watts
authors.affiliation: Institute of Farm Animal Genetics, Friedrich-Loeffler-Institut (FLI), Neustadt-Mariensee, Germany stefan.schwarz@fli.bund.de.
authors.forename: Stefan
authors.initials: S
authors.lastname: Schwarz
mesh_terms: D003227:Conjugation, Genetic; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D024881:Drug Resistance, Bacterial; D023061:Gene Order; D022761:Gene Transfer, Horizontal; D005798:Genes, Bacterial; D016680:Genome, Bacterial; D020071:Interspersed Repetitive Sequences; D016978:Mannheimia haemolytica / Q000235:genetics*; D008969:Molecular Sequence Data; D016979:Pasteurella multocida; D017422:Sequence Analysis, DNA
chemical_list: D004269:DNA, Bacterial
keywords: Pasteurellaceae; bovine respiratory disease; horizontal gene transfer; susceptibility testing