The pattern of CagA and VacA proteins in Helicobacter pylori seropositive asymptomatic children in western Saudi Arabia

OBJECTIVE: This study aimed to determine antibody prevalence to Helicobacter pylori (H. pylori) virulence factors CagA and VacA in asymptomatic H. pylori seropositive children in Jeddah, Kingdom of Saudi Arabia (KSA). The possibility of differences in antibodies response patterns was also investigated in relation to gender, nationality and age.

METHODS: Two hundred and twenty-four asymptomatic H. pylori seropositive children (mean age 9.3 ± 3.9 years; range, 1-14 years) were enrolled in this study from King Abdul-Aziz University and Maternity and Children's Hospitals, Jeddah, KSA, during the periods 2002-2003. The 35 kDa, CagA or VacA H. pylori antibodies were measured in the serum by immunoblot (Helico Blot 2) method.

RESULTS: Immunoblot assay yielded positive results in 215/224 seropositive asymptomatic children (96%). In those children, the prevalence of 35 kDa was 63.3%, VacA was 60%, CagA was 56.7% and for combined VacA and CagA antibodies was 45.6%. Prevalence of these bands did not show any difference between Saudi and non-Saudi children. Meanwhile, prevalence of 35 kDa, VacA, CagA, combined VacA and CagA antibodies were significantly elevated in males versus females (p<0.0001) and in children 10 years versus those in age groups 1-5 years and 6-9 years (p<0.0001).

CONCLUSION: This study showed high prevalence of H. pylori antibodies among asymptomatic children in Jeddah, KSA. The prevalence of antibodies against 35 kDa, CagA and VacA H. pylori antigens is higher in males and older children. The ELISA and immunoblot are non-invasive methods that were found to have adequate performance in pediatric population.