NEW PATHOGENICITY MARKERS FOR THE PEPTIC ULCER DISEASE FOUND IN HELICOBACTER PYLORI STRAINS ISOLATED FROM PORTUGUESE CHILDREN

Abstract

Aim: To search for new markers and potential virulence candidates of H. pylori. Methods: Comparison of 2 H. pylori strains isolated from a peptic ulcer and a gastritis from 2 young children, by PCR-based subtractive hybridization, showed the presence of 2 genes ulcer-associated and J99-specific. We investigated by PCR and sequencing the presence of these 2 genes, jhp562 and jhp870, on H. pylori strains isolated from 72 Portuguese children, mean age 10.8 years, 19 with peptic ulcer and 53 with gastritis only. We also evaluated if these genes where related to previously described virulence-associated genes. Results: Both jhp562 and jhp870 were significantly associated with peptic ulcer (p < 0.01, odds ratio (OR) of 9.48 and 6.87, respectively). The presence of the jhp562-positive genotype was strongly associated with vacAs1, cagA and babA2-positive status and oipA on status, while jhp870 was associated with vacAs1, cagA and babA2-positive status, hopQ I allele and oipA on status. The risk for peptic ulcer increased when jhp562-positive genotype was combined with cagA-positive genotype (OR = 8.84 vs OR = 6.72), vacAs1 (OR = 13.93 vs OR = 12.04) or both cagA-positive and vacAs1 genotypes (OR = 10.54 vs OR = 7.73). The association of jhp870 with cagA or vacA didn't improve the discrimination between disease outcome. Conclusions: These results suggest that jhp562 and jhp870 genes are candidates as virulence markers of H. pylori.