Characterization of three novel species infecting stomachs of dogs and cats: sp. nov., sp. nov., and sp. nov.

species infecting the stomachs of dogs and cats are potentially pathogenic and have been isolated from patients with gastric diseases. In the present study conducted in Japan, among the nine strains that we isolated from dogs and cats, NHP19-003 from a dog, and strains NHP19-012 and NHP21-005 from cats were identified to be the strains most closely related to ASB1 based on a 16S rRNA comparison (98.7-99.2% similarity with ASB1). However, none of their whole genomes showed more than average nucleotide identity (ANI) threshold value (95-96%) to any species (85.1, 86.7, and 86.6% ANI, respectively, with ASB1), including when compared to each other. Furthermore, NHP19-003, NHP19-012, and NHP21-005 exhibited protein profiles different from known gastric species, as revealed by MALDI-TOF MS, indicating that they are novel species. We, thus, propose these novel species as follows: sp. nov. (type strain NHP19-003 [=JCM 39159 = DSM 111619]), sp. nov. (type strain NHP19-012 [=JCM 39160]) and sp. nov. (type strain NHP21-005 [=JCM 39513]). These novel strains have respective GC content values of 48.3, 46.9, and 47.1%. Phylogenetic analysis based on gene sequences obtained from gastric specimens from 47 dogs and 24 cats in Japan revealed that 29.8% of dogs were infected with , while infected 44.7% of dogs and 12.5% of cats. Additionally, 10.6% of dogs and 20.8% of cats were infected with . Animal experiments have confirmed that these three novel species elicit gastric inflammatory responses. This study findings reveal the prevalence of novel gastric species in dogs and cats in Japan and their pathogenicity.