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