- The Helicobacter pylori P12 strain is a well-characterized clinical isolate that has become a standard model for investigating the molecular mechanisms of H. pylori pathogenesis.
- Originally isolated from a patient suffering from gastric adenocarcinoma, P12 carries key virulence factors that are highly relevant to gastric disease development.
- Among its notable features is the presence of the cytotoxin-associated gene pathogenicity island (cagPAI), which includes the gene cagA. This gene encodes the CagA protein, a major virulence factor that is injected into host gastric epithelial cells via a type IV secretion system (T4SS). Once inside the host cell, CagA undergoes tyrosine phosphorylation and interacts with multiple host signaling molecules, including SHP-2 and components of the MAPK and β-catenin pathways, leading to profound changes in cell morphology, proliferation, and inflammation.
- In addition to CagA, the P12 strain also expresses the vacuolating cytotoxin VacA, typically of the s1/m1 genotype, which is associated with higher cytotoxic activity. VacA induces vacuole formation in epithelial cells, disrupts mitochondrial function, and modulates immune responses, contributing to the persistence of infection and the promotion of chronic gastritis and peptic ulcers. The dual presence of functional CagA and VacA makes P12 an ideal model for studying the combined effects of these virulence factors on host cellular pathways.
- From a genomic perspective, H. pylori P12 has been fully sequenced, with a genome size of approximately 1.6 Mb and a GC content of about 38.8%. The strain is classified within the hpEurope population, which is commonly found in Western countries. In some variants, P12 contains plasmids such as pHel1 and pHel2, which have been explored for their roles in genetic mobility and potential contribution to virulence. The availability of complete genomic data facilitates the generation of isogenic mutants—such as CagA-deficient or T4SS-deficient strains—which are invaluable for dissecting specific host-pathogen interactions.
- Due to these characteristics, P12 is extensively used in infection models involving gastric epithelial cell lines such as AGS cells. It serves as a reference strain in many studies that explore host immune responses, bacterial adhesion, cytoskeletal rearrangements, and intracellular signaling alterations. Overall, H. pylori P12 is a powerful tool in H. pylori research, offering insights into bacterial pathogenesis, gastric carcinogenesis, and the broader mechanisms underlying persistent mucosal infections.
