Genomic and Histological Analysis of Helicobacter Himalayensis Sp. Nov. Isolated From Marmota Himalayana to Discovery the Potential Human Pathogen

Abstract Background: Helicobacter himalayensis was isolated from Marmota himalayana in the Qinghai-Tibet Plateau, China, and is a new non-H. pylori species, with unclear taxonomy, phylogeny, and pathogenicity. Methods and results: A comparative genomic analysis was performed between the H. himalayensis type strain 80(YS1) and other the genomes of Helicobacter species present in the National Center for Biotechnology Information (NCBI) database to explore the molecular evolution and potential pathogenicity of H. himalayensis. We also compared the lesions of gastrointestinal tissue samples from H. himalayensis-positive Marmota himalayana with H. himalayensis-negative Marmota himalayana using histology. H. himalayensis 80(YS1)T formed a clade with H. cinaedi and H. hepaticus that was phylogenetically distant from H. pylori. The genome of 80(YS1)T comprised 1,829,936 bp, with a 39.9% GC content, a predicted genomic island, and 1,910 predicted proteins. Comparatively, H. himalayensis has more genes for functions in “cell wall/membrane/envelope biogenesis” and “nucleotide transport and metabolism” sub-branches than the other compared helicobacters, and its genome contained 42 virulence factors genes, including that encoding cytolethal distending toxin (CDT). Histologically, the gastrointestinal mucosa of H. himalayensis-infected Marmota himalayana showed obvious lesions, implying that H. himalayensis is pathogenic to its host. Conclusions: We characterized the H. himalayensis 80(YS1)T genome, its phylogenetic position, and its potential pathogenicity. 80(YS1)T may be pathogenic to animals or humans; however, further understanding of the pathogenesis of this potentially pathogenic bacterium is required, which might help to manage H. himalayensis-induced diseases.