Helicobacter pylori cagA and vacA genotypes in Cuban and Venezuelan populations

Abstract

The aim of this study was to determine the presence of Helicobacter pylori cytotoxin-associated gene (cagA)/vacuolating cytotoxin gene (vacA) among patients with chronic gastritis in Cuba and Venezuela. Gastric antrum biopsies were taken for culture, DNA extraction and PCR analysis. Amplification of vacA and cagA segments was performed using two regions of cagA: 349 bp were amplified with the F1/B1 primers and the remaining 335 bp were amplified with the B7629/B7628 primers. The VA1-F/VA1-R set of primers was used to amplify the 259-bp (s1) or 286-bp (s2) product and the VAG-R/VAG-F set of primers was used to amplify the 567-bp (m1) or 642-bp (m2) regions of vacA. cagA was detected in 87% of the antral samples from Cuban patients and 80.3% of those from Venezuelan patients. All possible combinations of vacA regions were found, with the exception of s2/m1. The predominant combination found in both countries was s1/m1. The percentage of cagA+ strains was increased by the use of a second set of primers and a greater number of strains was amplified with the B7629/B7628 primers in the Cuban patients (p = 0.0001). There was no significant difference between the presence of the allelic variants of vacA and cagA in both populations. The predominant genotype was cagA+/s1m1 in both countries. The results support the necessary investigation of isolates circulating among the human population in each region

Relationship Between Drug Resistance and cagA Gene in Helicobacter pylori

“…The cagA gene is located at one end of a 40-kilobase DNA section called cag pathogenicity island (cag PAI) (28,29). The clinical relevance of the putative virulence-associated genes of H. pylori and geographical region is still a subject of controversy (28).…”

“…The clinical relevance of the putative virulence-associated genes of H. pylori and geographical region is still a subject of controversy (28). The prevalence of cagA-positive H. pylori strains varies from one geographic region to another (29). In this research such as the study from Isfahan-Iran (30), the prevalence of cagA-positive H. pylori strains was 68.3% which is more similar to the findings reported from Western countries (18,27) and Brazil (31) than those reported from East or Southeast Asia (14,28,32).…”

Helicobacter pylori Infection in Rural and Urban Dyspeptic Patients from Venezuela

“…5 In Venezuela, the prevalence of gastric infection by H. pylori has been reported ranging from 38% to 95% in the asymptomatic and symptomatic population in different localities, by using different detection methods. [6][7][8] In our laboratory, we have validated the detection of H. pylori by polymerase chain reaction (PCR) in string-absorbed gastric juice compared with gastroesophageal biopsies obtained by endoscopy in an urban population from Caracas. These studies showed that the string-absorbed gastric juice test is as sensitive as detection in gastroesophageal biopsies taken by endoscopy, allowing an accurate diagnosis of H. pylori infection by a less invasive method, 9-11 as was also validated in Lima, Perú by Velapatiño and others.…”

Polymorphism in the Helicobacter pylori CagA and VacA toxins and disease

“…144,148,[151][152][153][154]160 These studies show that most cagA positive H. pylori strains are associated with the vacA s1 and/ or m1 genotypes. 42,99,144,[150][151][152][153][154][155][161][162][163][164] Together these studies support the notion that individuals who carry cagA positive, vacA s1/m1 H. pylori isolates may be candidates for eradication therapy as a means to prevent severe disease (duodenal ulcers, peptic ulcer of Africa. As such, H. pylori has evolved mechanisms to persist within the harsh human gastric environment and may even serve to protect humans from diseases such as asthma, allergy, and esophageal cancer.…”