Objectives: In symptomatic patients resident in developed countries, a high prevalence of antibody to the cytotoxin-associated antigen (CagA) of Helicobacter pylori has been linked to the development of peptic ulcer disease and gastric cancer. This association has not been examined in developing countries, nor in asymptomatic subjects resident in either developed or developing countries. The aim of this study was to examine the seroprevalence of antibody to the CagA antigen; as well as other specific H. pylori antigens in symptomatic and asymptomatic individuals resident in Australia and China.
Methods: The Helico-blot 2.0 Western blot system was used for the detection of antibodies to specific antigens of H. pylori in sera obtained from the following H. pylori-positive groups: 19 Australian blood donors, 96 Australian nonulcer dyspepsia patients, 29 Australian duodenal ulcer patients, 35 asymptomatic Chinese subjects, and 48 Chinese gastric cancer patients.
Results: Nine antigens were commonly recognized by sera from Australian and Chinese subjects. These antigens were of molecular mass 19.5 kDa, 26.5 kDa, 35 kDa, 45 kDa, 60 kDa, 89 kDa (VacA), 116 kDa (CagA), and 180 kDA. A significant association between the prevalence of antibody to the CagA antigen and duodenal ulcer disease was observed in Australian subjects; however, no association between the prevalence of antibody to the CagA antigen and gastric cancer was found in Chinese subjects. In subjects from both countries, a significant association was found between antibody to the 30-kDa and 45-kDa antigens and more serious gastroduodenal disease.
Conclusion: The results of this study suggest that the cagA gene is not associated with the development of more serious gastroduodenal disease; however, it cannot be ruled out that this gene may be an important but insufficient factor in some disease processes.