Abstract 608: Examining H. pylori core genes for epidemiological typing

Abstract H. pylori is the major causative risk factor of a serious of diseases including gastric cancer. It is highly diverse. Conventional method of typing H. pylori has been based on seven MLST loci, which however are not sufficient to distinguish closely-related strains. High diverse core genes that are present in all H. pylori strains are potential good candidates for investigating genomic variation within closely-related strains, therefore improving our understanding of H. pylori -related disease epidemiology. In this study, we investigated the variation of the H. pylori genome, especially its core genes. We downloaded 80 H. pylori whole genome from National Center for Biotechnology Information (NCBI), and identified core genes (99% <= strains <= 100%: 840 genes), Soft core genes (95% <= strains < 99%: 185), Shell genes (15% <= strains < 95%: 933), Cloud genes (0% <= strains < 15%: 2313). Compared with other gene groups, we found that core genes have higher proportion of polymorphic sites, similar level of nucleotide diversity per site, higher recombination events per site, and lower number of gaps per site. In addition, core genes evolve slower than other gene groups with lower Tajima’s D value and nonsynonymous to synonymous ratio. Among the core and soft-core genes, we found that majority have low genetic diversity while a few showed higher diversity. We evaluated these high diverse core genes further in terms of their evolution, function and potential to serve as candidates to distinguish closely related H. pylori strains. Note: This abstract was not presented at the meeting. Citation Format: Guoqin Yu. Examining H. pylori core genes for epidemiological typing [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 608.