Submitted to: Vaccine
Publication Type: Proceedings
Publication Acceptance Date: February 4, 2001
Publication Date: N/A
Interpretive Summary: Avian coccidiosis is caused by several distinct species of Eimeria which are intracellular parasites. They infect mostly the host intestine, seriously damaging the intestinal epithelium and causes poor nutrient absorption. Currently, prophylactic medication and live parasite vaccines are used to control coccidiosis. However, increasing incidence of drug resistant parasites and the occurrence of antigenically variant Eimeria strains in the field prompted the development of novel control strategy for coccidiosis. In this report, ARS scientists demonstrate the effect of using a DNA vaccine using a coccidia gene which encodes an immunogenic surface protein to induce protective immune response against coccidia. Furthermore, ARS scientists identified various chicken cytokines which are produced by lymphocytes and demonstrated their effects on enhancing host immune response to DNA vaccination against coccidiosis. These findings provide first background knowledge which will facilitate the development o novel vaccine for coccidiosis.
Recent studies indicate that various chemokines and cytokines enhance host immunity to vaccination as an adjuvant. In order to investigate the role of various chicken cytokines in DNA vaccination against coccidiosis, recombinant pcDNA carrying IL-1B, IL-2, IL-8, IL-15, IFN-g, IFN-a, lymphotactin or TGF-B4 were coinjected into chickens at the time of vaccination with a DNA vaccine (pcDNA/3-1E) encoding the merozoite and sporozoite antigen of E. acervulina. Challenge infection was given one week after DNA immunization. Oocyst production was decreased significantly in the chickens which received pcDNA3-1E simultaneously with IL-15, IL-8, TGF-B4, or IL-1B compared to the chickens injected with pcDNA3-1E alone (p < 0.05). Furthermore, chickens which were vaccinated with pcDNA3-1E in combination with IL-8 or IL-15 had significantly increased CD3+ cells compared with chickens which received DNA vaccine alone or in combination with the other cytokine genes tested. These results provide first evidence in chickens that subcutaneously injected cytokine-encoding genes can modulate intestinal host lymphocyte responses and enhance host immune response to pcDNA3-1E recombinant vaccination against coccidiosis.