Novel CagA ELISA exhibits enhanced sensitivity of Helicobacter pylori CagA antibody

AIMTo develop a novel Helicobacter pylori (H. pylori) CagA antibody enzyme-linked immunosorbent assay (ELISA) suitable for detecting serum anti-CagA antibodies with high sensitivity.METHODSRecombinant 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.RESULTSRecombinant 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).CONCLUSIONThe novel ELISA is useful to detect anti-CagA antibodies in East Asian countries, and the titer may be a marker for predicting chronic gastritis.

Re-emerging threat of Trypanosoma cruzi vector transmission in El Salvador, update from 2018 to 2020

Background:Since the late twentieth century,Chagas disease gained global attention to suppress the vector burden as a main control strategy in endemic countries.In Central America,multi-national initiative successfully achieved significant reduction in the estimated disease prevalence as well as elimination of the region's principal vector species at the time in 2012.While the last decade has witnessed significant changes in ecosystem-such as urbanization and replacement of the main vector species-that can possibly affect the vector's habitation and residual transmission,the up-to-date vector burden in the region has not been evaluated thoroughly due to the cessation of active vector surveillance.The aim of this study was to update the risk of vector-borne Trypanosoma cruzi infection in El Salvador,the top Chagas disease-endemic country in Central America.Methods:A nationwide vector survey was conducted in the domestic environment of El Salvador from September 2018 to November 2020.The selection of the houses for inspection was based on expert purposeful sampling.Infection for T.cruzi was examined by microscopic observation of the insects'feces,followed by a species confrmation using PCR.The data were analyzed using R software version 4.1.3.Proportion estimates with 95%confidence intervals were inferred using the Jeffrey's method provided under the epiR package.Results:A total of 1529 Triatoma dimidiata was captured from 107 houses(infestation rate,34.4%;107/311)in all the fourteen departments of the country visited within the period;prevalence of T.cruzi infection was as high as 10%(153/1529).In the country,domestic T.dimidiata infestation was distributed ubiquitously,while T.cruzi infection rates varied across the departments.Five out of fourteen departments showed higher infection rates than the average,suggesting sporadic high-risk areas in the country.Conclusions:Our comprehensive study revealed substantial T.cruzi infection of T.dimidiata across the country,indicating potential active transmission of the disease.Therefore,strengthened surveillance for both vector and human infection is required to truly eliminate the risk of T.cruzi transmission in Central America.