- The hpEurope strain of Helicobacter pylori is a major phylogenetic population of this gram-negative, spiral-shaped bacterium, identified through multi-locus sequence typing (MLST).
- Prevalent across Europe, parts of the Middle East, and regions with European ancestry, such as the Americas and Australia, hpEurope is a genetically diverse population that reflects the complex history of human migrations and admixture in these areas.
- Unlike the African populations (hpAfrica1, hpAfrica2, hpNEAfrica) or the East Asian hpEastAsia, hpEurope is considered a hybrid population, with genetic contributions from ancient African (hpAfrica1-like) and Asian (hpAsia2-like) lineages, likely resulting from human migrations out of Africa and subsequent population mixing in Europe over tens of thousands of years. Its widespread distribution and association with a range of gastric diseases make hpEurope a critical strain for studying H. pylori’s evolutionary dynamics and clinical impact in Western populations.
- Genetically, hpEurope is characterized by a high degree of recombination, reflecting its hybrid ancestry. Phylogenetic analyses place hpEurope as a distinct clade, with allele combinations that show influences from both African and Asian H. pylori populations. Most hpEurope strains possess the cag pathogenicity island (cagPAI), which encodes the cagA gene and a type IV secretion system (T4SS) that injects CagA into host gastric epithelial cells, triggering inflammation and increasing the risk of peptic ulcers and gastric cancer. The cagA gene in hpEurope strains typically features Western-type EPIYA motifs (ABC-type), which are less oncogenic than the East Asian ABD-type found in hpEastAsia. The vacA gene commonly presents as the s1m1 allele, associated with high toxicity and severe pathology, though s1m2 and s2m2 alleles are also observed, particularly in less virulent strains. The dupA gene, linked to duodenal ulcer risk, is variably present in hpEurope, with some isolates showing truncated forms. This genetic variability, driven by recombination and adaptation to diverse host populations, makes hpEurope a key strain for comparative genomic studies.
- In terms of pathogenicity, hpEurope strains are associated with a broad spectrum of gastric diseases, including gastritis, peptic ulcers, and gastric cancer, with outcomes influenced by strain-specific virulence factors, host genetics, and environmental factors. In Europe, where H. pylori prevalence ranges from 20–50%, hpEurope strains are a leading cause of peptic ulcer disease and contribute significantly to gastric cancer, which is more prevalent in Western populations than in Africa. The presence of cagA-positive and vacA s1m1 genotypes in hpEurope strains correlates with higher risks of severe outcomes, though the Western-type cagA EPIYA motifs are less associated with gastric cancer than East Asian types. Host factors, such as European genetic predispositions (e.g., IL-1β polymorphisms), enhance inflammatory responses to hpEurope infections, increasing disease severity. Unlike the “African enigma,” where high H. pylori prevalence contrasts with low gastric cancer rates, Europe’s higher cancer rates align with hpEurope’s virulence and environmental risk factors like smoking and poor diet.
- Antibiotic resistance in hpEurope strains is a growing concern, particularly in Europe, where resistance rates are rising due to widespread antibiotic use. Clarithromycin resistance, often linked to A2143G mutations, ranges from 15–30% in many European countries, rendering standard triple therapies (clarithromycin, amoxicillin, proton pump inhibitor) ineffective in some regions. Metronidazole resistance varies widely (20–50%), while amoxicillin resistance remains low (<5%), though increasing in some areas. Tetracycline and fluoroquinolone resistance (10–20%) is also notable, with levofloxacin resistance driven by gyrA mutations. In Southern Europe, where resistance is higher, bismuth quadruple or concomitant therapies are increasingly recommended. The variability in resistance profiles across hpEurope strains underscores the need for antimicrobial susceptibility testing and tailored treatment regimens, particularly in high-prevalence areas like Eastern Europe.
- In research, hpEurope is pivotal for understanding H. pylori’s evolutionary history and its adaptation to diverse human populations. Its hybrid ancestry provides evidence of ancient human migrations, with genetic signatures from African and Asian lineages reflecting Europe’s role as a crossroads of population movements. Comparative genomic studies with hpAfrica1, hpNEAfrica, and hpEastAsia highlight hpEurope’s unique virulence profiles, such as its Western-type cagA motifs, which help explain differences in gastric cancer incidence. hpEurope’s high recombination rate is studied to understand bacterial adaptation and the spread of antibiotic resistance. Additionally, its association with higher gastric cancer rates in Europe makes it a focus for investigating host-pathogen interactions and developing preventive strategies, such as vaccines or targeted therapies. hpEurope’s genetic diversity, clinical significance, and global distribution make it a cornerstone of H. pylori research, informing both evolutionary biology and public health strategies.
