Published online Jan 7, 2017. doi: 10.3748/wjg.v23.i1.48
Peer-review started: August 16, 2016
First decision: September 20, 2016
Revised: October 3, 2016
Accepted: October 27, 2016
Article in press: October 27, 2016
Published online: January 7, 2017
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.
Recombinant East Asian-type CagA protein was purified and immobilized for ELISA. Serum samples from 217 Vietnamese 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 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.
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 genotype. The sensitivity of East Asian-type CagA ELISA was higher for subjects infected with East Asian-type 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).
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.
Core tip: We developed a novel East Asian-type CagA enzyme-linked immunosorbent assay (ELISA) to determine whether this method could detect CagA seropositivity with greater sensitivity in East Asian countries than the conventional anti-CagA antibody ELISA, which utilizes Western-type CagA as the antigen. Our findings revealed that conventional CagA ELISA underestimated CagA seropositivity in East Asian countries and the novel CagA ELISA could detect anti-CagA antibodies with higher sensitivity. In addition, the anti-CagA antibody titer tended to correlate with chronic inflammation in the stomach. Therefore, the titer of East Asian CagA ELISA may be a useful marker for predicting chronic inflammation in the gastric mucosa.