INDUCTION OF A LOCAL AND SYSTEMIC IMMUNE-RESPONSE USING CHOLERA-TOXINAS VEHICLE TO DELIVER ANTIGEN IN THE LAMINA PROPRIA OF THE CHICKEN INTESTINE

In this study, the humoral mucosal immune response to a recombinant Ei meria antigen (Ea1A) was enhanced using cholera toxin (CT). Chickens w ere primed intra-intestinally with Ea1A either conjugated or not to CT . The local and systemic antibody responses to both Ea1A and CT were d etermined to find out whether the chickens could respond to CT and whe ther both antigens had reached the lamina propria. In addition the eff ects of CT on lamina propria leukocytes were examined. The results sho wed that chickens had receptors on the caecal epithelium that could bi nd CT. At day 7 after administration, the number of CD4(+) and CD8(+) T lymphocytes in the lamina propria of the caecum had increased, indic ating that CT had a specific immunological effect, At this timepoint, anti-CT antibody containing cells were detected locally in the lamina propria of the caecum, In serum all antigen preparations containing CT induced IgM and IgG antibody titres specific for CT within 10 days af ter priming. In addition, the recombinant Ea1A antigen also induced se rum responses when administered together with CT or conjugated to CT, thus both CT and the antigen had reached the lamina propria, Neverthel ess, the Ea1A specific response was much higher in the primary respons e and after booster immunization when the antigen was conjugated to CT than when only mixed with CT. Therefore, we conclude that CT is a sui table adjuvant for intra-intestinal application in chickens, especiall y when the antigen is conjugated to it. (C) 1998 Elsevier Science B.V.