Helicobacter pylori cagA and vacA cytotoxin genes in Changsha, China

Abstract

Cytotoxin-associated protein (cagA) and the vacuolating cytotoxin (vacA) encoded by cagA and vacA genes are virulence determinants of Helicobacter pylori. In earlier studies among Chinese patients, all H. pylori strains were cagA-positive and vacAs1a/m2 type. Here, we determine the cagA, vacA and allele status of H. pylori strains isolated from patients with upper gastrointestinal symptoms in Changsha, China. Forty strains of H. pylori isolated from patients with peptic ulcer disease between March 1997 and August 1999 were recovered from storage at -80 degrees C and studied by the polymerase chain reaction (PCR) for cagA and vacA genotypes. cagA was positive in 75% of H. pylori isolates. Patients with peptic ulcer demonstrated cagA in 83% (15/18), compared with 68% (15/22) patients with superficial gastritis. vacAs1 allele was carried in 82.5% (33/40) isolates, of which 52.5% (21/40) were subtype vacAs1a/m2 and 17.5% (7/40) were subtype vacAs1b/m2.

Distinctiveness of the cagA Genotype in Children and Adults with Peptic Symptoms in South China

“…In East Asia, most H. pylori strains infecting people are cagA positive, especially in areas with high incidence of gastric cancer [34]. While in Guangzhou, although the incidence of gastric cancer is low, the frequency of cagA in children (73.6%) and adults (82.3%) with peptic symptoms is high (Table 3), similar to reports from other areas of China [21,35,36], implying the cagA-positive strains are predominant in the infected Chinese. Further-more, there was no statistical difference in frequency of cagA between children and adults, which is inconsistent with that found in Western countries, where cagA-negative strains are more prevalent in children and than in adults [2,33,37].…”

Genotipificación de aislados clínicos de Helicobacter pylori en base a genes asociados a virulencia cagA, vacA y babA2: Primer aislamiento de una cepa babA2 positiva en pacientes chilenos

“…También contamos con información patofisiológica útil, que puede tener implicancias clínicas significativas 30 , pues estudios de poblaciones de oriente y occidente señalan que los factores de virulencia de H pylori varían de acuerdo a la localidad geográfica y a la edad del individuo 31 . Así, se ha demostrado que los factores de virulencia difieren en las cepas obtenidas de diferentes poblaciones 16,[32][33][34] . Esta diferencia en localidad geográfica se ha puesto de manifiesto en estudios en Japón, que muestran una prevalencia de babA2 cercana a 85% 15 , y en resultados obtenidos de población coreana, que presentaron 36,1% de cepas babA2 positivas 16 .…”