Figure 1.

Experimental design. Helicobacter pylori strain B128 was originally isolated from a human patient.⁵⁴ Strain B128 (green) was used for orogastric challenge of Mongolian gerbils and was passaged three times through gerbils in a previous study.²⁸ The in vivo-adapted output strain, designated H. pylori strain B8 (orange), was isolated from those gerbils, sequenced and used as the reference strain in this study.¹⁹ In an independent experiment, strain B128 (green) was also used for orogastric challenge of a single Mongolian gerbil, and the in vivo-adapted output strain isolated from this gerbil was designated H. pylori strain 7.13 (orange).²⁷ Carcinogenic H. pylori strain 7.13 was then used to infect another cohort of Mongolian gerbils maintained on either iron-replete or iron-depleted diets.¹⁷ Single colonies (n=3) from three independent gerbils maintained on iron-replete diet (n=9) and three independent gerbils maintained on iron-depleted diet (n=9) were subjected to whole genome sequence analysis. In vivo-adapted strain from iron-replete (red) and iron-depleted (blue) conditions was also compared with previously described H. pylori single colonies (n=4) harvested from one gerbil maintained on a regular salt (pink) or high salt (light blue) diet.²¹