Genótipos cagA , vacA e alelos e sítios de fosfolilação de tirosina da proteína caga do h. pylori em pacientes com e sem história familiar de câncer gástrico

Abstract

The H. Pylori strains demonstrate a high level of phenotypic and genotypic diversity, the expression of various genes, which confer greater pathogenicity to the bacteria. Relatives of patients with gastric cancer have a higher risk of developing gastric diseases, especially if they are infected with more virulent strains of H. pylori. The objective was to characterize the strains of H. pylori, the presence of genes vacA, cagA, and sites of tyrosine phosphorylation of CagA protein - EPIYA in patients with and without family history of gastric cancer, and correlate the presence of the cagA gene to the level of activity and inflammation chronic gastritis. The genotyping of strains of H. pylori was performed by PCR and sequencing of the phosphorylation sites EPIYA. We evaluated 94 biopsy samples of gastric mucosa from dyspeptic patients H. pylori positive, 55 with a family history of gastric cancer and 39 without family history. All genotyped strains were vacA positive, and 45.7% with the vacA allele s1m1; s1m2 vacA 26.6%, 4.3% were vacA s2m1; 10.6% vacA s2m2; 3 hybrid strains and 9 (9.6 %) showed only the allele sequence signal (s). Of the 94 strains genotyped 87.2% were cagA positive, with no statistical difference between groups of familiar and unfamiliar (92.7% vs 82.0%, p = 0.058). The cagA gene was present in most patients with gastritis, with statistical significance in the group of relatives of cancer (p = 0.004). The degree of activity and inflammation of gastritis, was more significant in the group of patients with cagA positive strains, with pangastritis Corpal and gastritis. In the antrum, there were significant only in relation to the activity of gastritis. The studed strains, 93.9% showed EPIYA phosphorylation sites, with 59.2% of these had only one site, 38.2% with two sites and 2.6% with three sites. There was no statistical difference in the number of sites EPIYA between the groups. It is important to genetically characterize the strains of H. pylori to establish clearly its role in different clinical conditions related to it. Keywords: H. pylori.