Genetic immunization of ducks for production of antibodies specific to Helicobacter pylori UreB in egg yolks

Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warszawa, Poland.
Acta biochimica Polonica (Impact Factor: 1.15). 02/2005; 52(1):261-6.
Source: PubMed


Following genetic immunization of laying ducks with a plasmid expressing Helicobacter pylori UreB (large subunit of urease), IgY against UreB were obtained from egg yolks. These polyclonal and monospecific IgY antibodies are of higher-titer and specifically recognize recombinant H. pylori urease purified from Escherichia coli. To our knowledge this is the first report describing generation of IgY antibodies directed against antigens of H. pylori by DNA-based immunization.

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Available from: Agnieszka Sirko,
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    • "In previous studies, in vivo H. pylori-eliminating capacity of IgY specific for urease or subunit of urease has been demonstrated [37,40-42]. However, since the titer of such antibodies tended to rapidly decrease at low pH, researches has focused on their efficacy in the stomach [40,43]. "
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    ABSTRACT: Effects of egg york containing IgY specific for Helicobacter pylori on the bacterial growth and intragastric infection were investigated in comparison with a proton-pump inhibitor pantoprazole. For in vitro anti-bacterial activity test, H. pylori (1×10(8) CFU/mL) was incubated with a serially diluted IgY for 3 days. As a result, IgY fully inhibited the bacterial growth at 16 mg/mL, which was determined to a minimal inhibitory concentration. In vivo elimination study, male C57BL/6 mice were infected with the bacteria by intragastric inoculation (1×10(8) CFU/mouse) 3 times at 2-day intervals, and 2 weeks later, orally treated twice a day with 50, 100, 200 or 500 mg/kg IgY for 18 days. After the final administration, biopsy sample of the gastric mucosa was assayed for the bacterial identification via urease, oxidase, catalase, nitrate reduction and H(2)S tests in addition to microscopic examination for mucosal inflammation. In CLO kit test, 75, 50, 12.5 and 12.5% of the animals revealed positive reaction following treatment with 50, 100, 200 and 500 mg/kg IgY, respectively, resulting in a superior efficacy at 200 mg/kg than 30 mg/kg pantoprazole that displayed 75% elimination. The CLO test results were confirmed by bacterial identification. Microscopic examination revealed that H. pylori infection caused severe gastric mucosal inflammation, which were not observed in the CLO-negative mice following treatment with IgY or pantoprazole. Taken together, IgY inhibited the growth of H. pylori, and improved gastritis and villi injuries by eliminating the bacteria from the stomach. The results indicate that IgY could be a good candidate overcoming tolerance of antibiotics for the treatment of H. pylori-mediated gastric ulcers.
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    ABSTRACT: We have recently demonstrated, using the duck Hepatitis B virus (DHBV) model, closely related to human HBV, that following DNA immunization of breeding ducks with a plasmid encoding the targeted protein, specific and biologically active IgY (egg yolk immunoglobulines) are vertically transmitted from their serum into the egg yolk from which they can be extracted and purified. Thus an egg can be considered as a small "factory" for antibody production, since about 60-100 mg of purified IgY can be obtained from each egg yolk of a DNA-immunized duck. One of the major advantages of this new method of "DNA-designed" IgY antibodies is their production via immunization with a gene vector that expresses a corresponding antibody in situ in the cells of an avian host. Therefore this approach allows direct generation of antibodies from plasmid DNA and avoids the costly and tedious preparation of purified antigens required for conventional antibody production. In addition, duck IgY are of remarkable high affinity, avidity and are highly neutralizing. Moreover, the epitope pattern of IgY generated by DNA immunization of ducks is closely related to that observed in viral infection. Such duck IgY are also of particular value as immunodiagnostic tools, since they do not cross-react serologically with mammalian immunoglobulins and complement. Because IgY are resistant to the gastric barrier, the recently described DNA-designed IgY specific to H. pylori Urease B can be of particular interest for passive immunotherapy of gastrointestinal tract infections. Another interesting application is the recent generation in our laboratory of DNA-designed IgY antibodies specific to HBsAg mutants. These antibodies are currently being used to design new diagnostic assay for detection of HBV mutants that are undetectable by actual tests. Moreover, this approach allowing a quick and inexpensive production of a new generation of antibodies will provide pertinent tools to link the fields of genomics and protcomics.
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    ABSTRACT: Background: Helicobacter pylori multiplies and causes infection in human gastric mucosal layer. New approaches have focused on using specific treatments, such as immunotherapy, to limit this infection. Urease, as one of the most important virulent and antigenic factors of the bacterium, is a suitable target for this purpose. Patients and methods: In order to prepare recombinant proteins, the synthetic genes for total ureC protein (UreCt) and its N (ureCn) and C (ureCc) terminal fragments were ligated into pET28a. The recombinant proteins were expressed in E. coli BL21(DE3). White leghorn hens were injected with the purified recombinant proteins. IgY recovered from egg yolk, using PEG precipitation. Finally, urease neutralizing ability of the antibodies was evaluated by urease activity assay in presence of the purified IgY. Results: SDS-PAGE analysis revealed a good expression and purification of the recombinant proteins. Indirect ELISA observation demonstrated high antibody titer in sera and egg yolks and high ability of IgY Anti-UreCt and IgY Anti- UreCc antibodies in recognition of urease subunit C. Anti-UreCT and Anti-UreCc IgYs were more potential H.pylori urease inhibitors than Anti-UreCn. Conclusion: While all three UreC fragments induce prophylactic responses. UreCt and UreCc possess almost equal responses. Anti-UreCc IgY has advantage of smaller size and is preferred for its activity and easier protein recovery and purification process. These features emphasize on importance of simpler, easier and cost effective antibody production.
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