부산대학교 도서관

The aim of this study was to determine the occurrence and relationship between the presence of Lewis antigen and other virulence factors (cagA and vacA) in H. pylori strains obtained from paediatric patients. Methods: 36 H. pylori strains were obtained from paediatric patients attending to the Gastroenterology Unit due to different symptomatology. Upper endoscopy was performed and biopsy cultured following standard methodology. Strains were conserved at -70°C until used. Lipopolysaccharide (LPS) was extracted from a 48 h culture by mini-phenol water and detection of Lewis antigen was determined by a standard serodot method using monoclonal anti-LewisX, -LewisY, -LewisA, -LewisB, sialyl-LewisX and H type 1, and peroxidase-labelled secondary antibodies. DNA was extracted from a 48 h culture and PCR performed to detect cagA gene, and vacA s1- and s2-alleles. Results: The frequency of H. pylori strains expressing LewisX was 61.1% (22 strains) and LewisY was 58.3% (21 strains). None of the strains tested expressed LewisA, LewisB, sialyl-LewisX or H type 1. Of the strains tested, 47.2% expressed LewisX and LewisY simultaneously, 13.9% only LewisX, 11.l% only LewisY and 27.8% no Lewis antigen. In 31.2% of strains, the expected cagA fragment was amplified by PCR; 34.4% carried the s1-allele and 65.6% the s2-allele. A correlation was observed between cagA positivity and the vacA s1-allele (p=0.05), and between the presence of LewisX and LewisY (p<0.01). Also, the presence of the cagA gene was associated with the presence of LewisX (p<0.01) and LewisY (p<0.001). Conclusions: Of the paediatric-originating strains tested, a lower percentage expressed both LewisX and LewisY than previously reported in isolates from adults. Also, a low prevalence of cagA gene and vacA s1-allele was observed in strains from paediatric patients. Furthermore, occurrence of cagA was associated with vacA si-allele and to LewisX and LewisY in this population. [ABSTRACT FROM AUTHOR]