Preventive effect of anti-VacA egg yolk immunoglobulin (IgY) on Helicobacter pylori-infected mice

Background Helicobacter pylori, a gram-negative bacterium, is the causative agent of gastric disorders and gastric cancer in the human stomach. Vacuolating cytotoxin A (VacA) is among the multi-effect protein toxins released by H. pylori that enables its persistence in the human stomach. Methods To evaluate the effect of anti-VacA egg yolk immunoglobulin (anti-VacA IgY) on H. pylori infection, a highly specific anti-VacA IgY was produced from egg yolks of hens immunized with a mixture of two purified recombinant VacAs. Female C57BL/6 mice were supplemented anti-VacA IgY daily with drinking water for 2 weeks before and 4 weeks after H. pylori ATCC 43504 inoculation. Anti-VacA IgY recognized both native and denatured structures of VacA by enzyme-linked immunosorbent assay and immunoblotting analyses, respectively. Results Oral administration of anti-VacA IgYs significantly (p <.05) reduced the serum levels of anti-H. pylori antibodies compared to those in the H. pylori-infected, untreated group. The reduction in the immune response was accompanied by a significant (p <.05) decrease in eosinophilic infiltration of the stomach in anti-VacA IgY treated group compared to other groups. Concomitantly, H. pylori–induced histological changes and H. pylori antigen-positivity in gastric tissues were decreased significantly (p <.05) in anti-VacA IgY treated group similar to the control group. Conclusions Oral administration of anti-VacA IgY is correlated with a protective effect against H. pylori colonization and induced histological changes in gastric tissues. Our experimental study has proved that it is expected to be a new drug candidate of Hp infection by further study.