title: Emended description of Actinobacillus capsulatus Arseculeratne 1962, 38AL.
abstract: The taxonomic position of Actinobacillus capsulatus, a member of the family Pasteurellaceae found in rabbits, hares and hamsters, has been challenged. 16S rRNA gene (rrs) sequence data show the species to be heterogeneous. Using a polyphasic approach, 23 strains that were identified previously as belonging, or closely related, to A. capsulatus were analysed. Eighty characters were included in the phenotypic analysis. Phylogenetic analysis was done based on rrs, rpoB, infB and recN sequences. In addition, the recN sequence similarities were used to calculate the whole-genome sequence relatedness of all strains investigated as well as that with other members of the family Pasteurellaceae. The phenotypic analysis allowed identification of five groups. The major group of 17 strains could be classified as A. capsulatus. Two hamster isolates were closely related to A. capsulatus but differed in a few characters. Single isolates from a rabbit and snowshoe-hare were phenotypically related to Actinobacillus suis. One rabbit isolate was related to the genus Mannheimia, while another isolate could not be classified phenotypically with known taxa. The phylogenetic analysis confirmed the phenotypic grouping. In contrast to the rrs-based tree, the A. capsulatus strains clustered unambiguously with the type species and related species of the genus Actinobacillus in the rpoB-, infB- and recN-based trees. Genome similarity comparison using recN finally confirmed the high genomic relationship of the A. capsulatus strains with the type species and related species of the genus Actinobacillus and allowed a clear assignment of the other unrelated strains to the phenotypic and phylogenetic clusters outlined. The present findings allow the description of A. capsulatus to be emended and separate it more clearly from other species, both phenotypically and genotypically. The type strain of A. capsulatus is CCUG 12396(T) (=Frederiksen 243(T)=ATCC 51571(T)=NCTC 11408(T)=CIP 103283(T)).
authors.affiliation: Institute of Veterinary Bacteriology, University of Bern, CH-3001 Bern, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Kuhnert
authors.affiliation: Institute of Veterinary Bacteriology, University of Bern, CH-3001 Bern, Switzerland.
authors.forename: Bożena M
authors.initials: BM
authors.lastname: Korczak
authors.affiliation: Department of Veterinary Pathobiology, The Royal Veterinary and Agricultural University, DK-1870 Frederiksberg C, Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Christensen
authors.affiliation: Department of Veterinary Pathobiology, The Royal Veterinary and Agricultural University, DK-1870 Frederiksberg C, Denmark.
authors.forename: Magne
authors.initials: M
authors.lastname: Bisgaard
mesh_terms: D000188:Actinobacillus / Q000145:classification* / Q000235:genetics; D000189:Actinobacillus Infections / Q000382:microbiology; D000818:Animals; D006224:Cricetinae; D004269:DNA, Bacterial / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D011817:Rabbits
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S