AIM To develop a novel Helicobacter pylori(H.pylori)CagA antibody enzyme-linked immunosorbent assay(ELISA)suitable for detecting serum anti-CagA antibodies with high sensitivity.METHODS Recombinant East Asian-type CagA protein was purified and immobilized for ELISA.Serum samples from 217Vietnamese individuals(110 H.pylori-infected and107 uninfected individuals)were applied.Conventional ELISA from Western-type CagA and our East Asian-type CagA ELISA were evaluated by comparing 38 subjects with the Western-type genotype and 72 subjects with the East Asian-type cagA genotype.Histological scores of the gastric mucosa were determined using the updated Sydney System to examine the relationship with anti-CagA antibody titers.RESULTS Recombinant 70-100 k Da fragments were immobilized on the ELISA plate.In ROC analysis,the area under the curve of our East Asian-type CagA ELISA was comparable to that of conventional CagA ELISA.The sensitivity of the two ELISAs differed depending on the cagA genotype.The sensitivity of East Asian-type Cag A ELISA was higher for subjects infected with East Asiantype cagA H.pylori(P<0.001),and the sensitivity of the conventional CagA ELISA tended to be higher for subjects infected with Western cagA H.pylori(P=0.056).The titer of anti-CagA antibody tended to correlate with monocyte infiltration scores(r=0.25,P=0.058)and was inversely correlated with H.pylori density(r=-0.26,P=0.043).CONCLUSION The novel ELISA is useful to detect anti-CagA antibodies in East Asian countries,and the titer may be a marker for predicting chronic gastritis. AIM To develop a novel Helicobacter pylori (H. pylori) CagA antibody enzyme-linked immunosorbent assay (ELISA) suitable for detecting serum anti-CagA antibodies with high sensitivity. METHODS Recombinant East Asian-type CagA protein was purified and immobilized for ELISA. Samples from 217 V enient individuals (110 H. pylori-infected and 107 uninfected individuals) were applied. Conventional ELISA from Western-type CagA and our East Asian-type CagA ELISA were evaluated by comparing subjects with the Western-type genotype and 72 subjects with the East Asian-type cagA genotype. Histological scores of the gastric mucosa were determined using the updated Sydney System to examine the relationship with anti-CagA antibody titers. RESULTS Recombinant 70-100 kDa fragments were immobilized on the ELISA plate. In ROC analysis, the area under the curve of our East Asian-type CagA ELISA was comparable to that of conventional CagA ELISA. The sensitivity of the two ELISAs differed depending on the cagA geno type. sensitivity of East Asian-type Cag A ELISA was higher for subjects infected with East Asiantype cagA H. pylori (P <0.001), and the sensitivity of the conventional CagA ELISA tended to be higher for subjects infected with Western cagA H. pylori (P = 0.056). The titer of anti-CagA antibody tended to correlate with monocyte infiltration scores (r = 0.25, P = 0.058) and was inversely correlated with H. pylori density (r = -0.26, P = 0.043). CONCLUSION The novel ELISA is useful to detect anti-CagA antibodies in East Asian countries, and the titer may be a marker for predicting chronic gastritis.