| Criteria | Strain 26695 | Strain J99 | Strain P12 | Strain PMSS1 | Remarks |
| Geographic Origin | UK patient with gastritis | US patient with duodenal ulcer | German patient with gastric adenocarcinoma | US patient with duodenal ulcer | Reflects strain-specific geographic and clinical diversity |
| Clinical Source | Gastritis | Duodenal ulcer | Gastric adenocarcinoma | Duodenal ulcer | Associated with different stages and outcomes of gastric disease |
| Genome Size | ~1.67 Mb | ~1.64 Mb | ~1.65 Mb | ~1.67 Mb | Comparable genome sizes with differences in plasticity zones |
| Cag Pathogenicity Island | Intact and functional | Intact and functional | Intact, well-characterized | Intact and highly active | All strains are cagA-positive and used in CagA function studies |
| CagA EPIYA Motifs | Western-type (EPIYA-ABC) | Western-type, fewer repeats | Western-type, often studied for delivery and phosphorylation | Western-type with strong phosphorylation potential | Important for SHP2 binding and phosphorylation-dependent signaling |
| VacA Genotype | s1/m1 (highly cytotoxic) | s1/m2 (less toxic) | s1/m1 | s1/m1 | 26695, P12, and PMSS1 show stronger vacuolating toxin activity |
| Genetic Tools Availability | Extensive (first genome sequenced) | Second sequenced, widely used | Used in host-pathogen interaction studies | Gold standard for murine infection models | PMSS1 is highly transformable and mouse-colonization competent |
| Mouse Colonization | Poor | Poor | Not well-characterized | Strong colonizer in C57BL/6 mice | PMSS1 is ideal for in vivo infection and chronic disease modeling |
| Natural Competence | Moderate | High | Moderate | High | Useful for transformation and genetic manipulation |
| Plasticity Zones | Present | Fewer than 26695 | Contain diverse virulence-related genes | Present | Reflects horizontal gene transfer and genomic plasticity |
| Use in Research | Functional genomics, virulence studies | Evolutionary genomics | Host-pathogen interaction, CagA delivery | In vivo infection, inflammation, and CagA studies | Each strain provides unique advantages depending on research focus |
