Reclassification of [Haemophilus] haemoglobinophilus as Canicola haemoglobinophilus gen. nov., comb. nov. including Bisgaard taxon 35

Abstract

[ Haemophilus ] haemoglobinophilus and the unpublished Bisgaard taxon 35 are associated with respiratory and urogenital tract infections in dogs. A total of 21 strains including the type strain of [ Haemophilus ] haemoglobinophilus were included in the investigation. Strains of [ Haemophilus ] haemoglobinophilus and taxon 35 formed a monophyletic group demonstrating at least 97.8 and 96.5% similarities within the group based upon 16S rRNA and rpoB gene sequence comparisons, respectively. Glaesserella australis was the most closely related species to [ Haemophilus ] haemoglobinophilus and taxon 35 with 96.1 % 16S rRNA gene sequence similarity which is slightly higher than the 95 % separating most genera of the family Pasteurellaceae . However, the conserved protein sequence phylogeny documented a unique position of [ Haemophilus ] haemoglobinophilus with only 81 % identity to the most closely related species, genomospecies 1 of the genus Rodentibacter which is lower than the 85 % separating most genera of the family Pasteurellaceae . The conserved protein sequence identity to Haemophilus influenzae , the type species of the genus, was 77%, demonstrating that [ Haemophilus ] haemoglobinophilus is not properly classified as a member of the genus Haemophilus . On the basis of the phylogenetic comparisons, the taxa [ Haemophilus ] haemoglobinophilus and taxon 35 are proposed to be included with a novel genus Canicola with one species, Canicola haemoglobinophilus which is reclassified from [ Haemophilus ] haemoglobinophilus. Phenotypic characters obtained with isolates genetically approved to represent Canicola haemoglobinophilus were in accordance with those of the members of the family Pasteurellaceae, and the novel genus can be separated from most of the existing genera by a positive catalase reaction, lack of V-factor requirement for growth, lack of haemolysis of blood agar and negative Voges–Proskauer and urease tests. The novel genus cannot be separated by biochemical and physiological characteristics alone from the genera Aggregatibacter , Avibacterium , Frederiksenia and Spirabiliibacterium . However, MALDI-TOF mass spectroscopy and also RpoB amino acid signatures allowed a clear separation from these taxa, supporting the existence of a novel genus. The DNA G+C content is 37.0–37.8 mol% for the genus, based on the whole genomic sequences. The type strain of Canicola haemoglobinophilus is CCUG 3714T (=ATCC 19416T=NCTC 1659T) isolated in 1901 from the prepuce of a dog in Germany.