New Insights into CRISPR-like Arrays in Helicobacter pylori: An Exploratory Analysis from Genomic Data.

Helicobacter pylori (H. pylori) is a highly adaptable gastric pathogen with marked genomic plasticity. Whilst functional CRISPR-Cas systems provide adaptive immunity in many bacteria, they have not been identified in H. pylori, unlike CRISPR-like sequences. In this study, eight H. pylori genomes were analysed using the bioinformatics tools CRISPRCasFinder, CRISPRCasTyper, and CRISPRloci. A total of 25 CRISPR-like arrays were identified, showing high conservation (88%) both between and within strains, suggesting that these arrays are not random remnants but rather organised structures possibly involved in cellular processes. Notably, a structural association was observed between the CRISPR-like sequences and the cag pathogenicity island (CagA-PAI). Conversely, CagA-PAI instability in specific strains was observed in the presence of the TnpA and TnpB transposons. Furthermore, in strain 29CaP, CRISPR-like assemblies were located in genomic proximity to the prophage Helico 1961P, leading to the hypothesis of a compensatory or regulatory effect in the absence of CagA-PAI. Taken together, these findings indicate that CRISPR-like arrays in H. pylori characterise a genomic architecture within regions of high plasticity. This study provides a solid exploratory foundation for future functional research on the adaptive and pathogenic evolution of H. pylori.