title: Comparative Genomics of Campylobacter fetus from Reptiles and Mammals Reveals Divergent Evolution in Host-Associated Lineages.
abstract: Campylobacter fetus currently comprises three recognized subspecies, which display distinct host association. Campylobacter fetus subsp. fetus and C fetus subsp. venerealis are both associated with endothermic mammals, primarily ruminants, whereas C fetus subsp. testudinum is primarily associated with ectothermic reptiles. Both C. fetus subsp. testudinum and C. fetus subsp. fetus have been associated with severe infections, often with a systemic component, in immunocompromised humans. To study the genetic factors associated with the distinct host dichotomy in C. fetus, whole-genome sequencing and comparison of mammal- and reptile-associated C fetus was performed. The genomes of C fetus subsp. testudinum isolated from either reptiles or humans were compared with elucidate the genetic factors associated with pathogenicity in humans. Genomic comparisons showed conservation of gene content and organization among C fetus subspecies, but a clear distinction between mammal- and reptile-associated C fetus was observed. Several genomic regions appeared to be subspecies specific, including a putative tricarballylate catabolism pathway, exclusively present in C fetus subsp. testudinum strains. Within C fetus subsp. testudinum, sapA, sapB, and sapAB type strains were observed. The recombinant locus iamABC (mlaFED) was exclusively associated with invasive C fetus subsp. testudinum strains isolated from humans. A phylogenetic reconstruction was consistent with divergent evolution in host-associated strains and the existence of a barrier to lateral gene transfer between mammal- and reptile-associated C fetus Overall, this study shows that reptile-associated C fetus subsp. testudinum is genetically divergent from mammal-associated C fetus subspecies.
authors.affiliation: Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, the Netherlands.
authors.forename: Maarten J
authors.initials: MJ
authors.lastname: Gilbert
authors.affiliation: US Department of Agriculture, Produce Safety and Microbiology Research Unit, Agricultural Research Service, Albany, California.
authors.forename: William G
authors.initials: WG
authors.lastname: Miller
authors.affiliation: US Department of Agriculture, Produce Safety and Microbiology Research Unit, Agricultural Research Service, Albany, California.
authors.forename: Emma
authors.initials: E
authors.lastname: Yee
authors.affiliation: Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, the Netherlands WHO Collaborating Center for Campylobacter/OIE Reference Laboratory for Campylobacteriosis, Utrecht, the Netherlands.
authors.forename: Aldert L
authors.initials: AL
authors.lastname: Zomer
authors.affiliation: Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, the Netherlands WHO Collaborating Center for Campylobacter/OIE Reference Laboratory for Campylobacteriosis, Utrecht, the Netherlands.
authors.forename: Linda
authors.initials: L
authors.lastname: van der Graaf-van Bloois
authors.affiliation: Biotechnology Core Facility Branch, Division of Scientific Resources, National Center for Emerging and Zoonotic Infectious Diseases, CDC, Atlanta, Georgia.
authors.forename: Collette
authors.initials: C
authors.lastname: Fitzgerald
authors.affiliation: School of Medicine and Dentistry, University of Aberdeen, United Kingdom.
authors.forename: Ken J
authors.initials: KJ
authors.lastname: Forbes
authors.affiliation: College of Medicine, Institute of Life Science, Swansea University, United Kingdom.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Méric
authors.affiliation: College of Medicine, Institute of Life Science, Swansea University, United Kingdom MRC Cloud-Based Infrastructure for Microbial Bioinformatics (CLIMB) Centre, Swansea University, United Kingdom Department of Zoology, University of Oxford, United Kingdom.
authors.forename: Samuel K
authors.initials: SK
authors.lastname: Sheppard
authors.affiliation: Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, the Netherlands WHO Collaborating Center for Campylobacter/OIE Reference Laboratory for Campylobacteriosis, Utrecht, the Netherlands Central Veterinary Institute of Wageningen UR, Lelystad, the Netherlands.
authors.forename: Jaap A
authors.initials: JA
authors.lastname: Wagenaar
authors.affiliation: Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, the Netherlands WHO Collaborating Center for Campylobacter/OIE Reference Laboratory for Campylobacteriosis, Utrecht, the Netherlands b.duim@uu.nl.
authors.forename: Birgitta
authors.initials: B
authors.lastname: Duim
mesh_terms: D000818:Animals; D002169:Campylobacter Infections / Q000235:genetics* / Q000382:microbiology; D002168:Campylobacter fetus / Q000235:genetics* / Q000472:pathogenicity; D019143:Evolution, Molecular; D022761:Gene Transfer, Horizontal; D014644:Genetic Variation; D054884:Host-Pathogen Interactions / Q000235:genetics*; D006801:Humans; D008322:Mammals / Q000235:genetics / Q000382:microbiology; D010802:Phylogeny; D012104:Reptiles / Q000235:genetics / Q000382:microbiology; D013045:Species Specificity
keywords: campylobacter fetus; comparative genomics; evolution; mammal; recombination; reptile