Analysis of immune responses against H pylori in rabbits

To investigate the immunogenicity of H pylori proteins, to evaluate the production rate of anti H pylori IgG antibodies in relation to time and to demonstrate the fidelity of newly optimized in-house enzyme-linked immunosorbent assay (ELISA) technique as an alternative for H pylori infection assay.

In the present study, 100 microg of formalin-fixed H pylori whole cell antigens was injected into an experimental animal (New Zealand white female rabbit) intramuscularly on d 0, 16, 27 and 36. The first two doses were injected with adjuvants. On d 0, a serum sample was collected from the rabbit before immunization and this pre-immunized serum was used as a negative control for the whole study. To evaluate the immunogenic responses of the injected antigen, serum samples were collected from the rabbit at regular intervals up to d 42. The sera were analyzed using in-house ELISA and Western blot techniques.

The production of anti H pylori IgG antibodies in the rabbit in response to the injected antigen increased almost exponentially up to d 14 and after that it was maintained at the same level until the last day (d 42). By analyzing the immune profiles of immunized sera, 11 proteins were identified to be immunogenic, among them 2 (approximately 100 kDa and 85 kDa) were most prominent.

Analysis of the immune responses against pathogenic microorganisms like H pylori is necessary for the development of various diagnostic and preventive approaches. The results of this experiment reveal that the formalin-fixed H pylori whole cell antigens injected into the rabbit are highly immunogenic. These prominent proteins (approximately 100 kDa and 85 kDa) might have higher immunogenic effects among humans infected with H pylori and some of these immunogenic proteins can be included in diagnostic approaches based on serology and also for vaccine formulation. The in-house ELISA is a promising alternative compared to invasive techniques.