Vaccination with Eimeria tenella elongation factor-1a with IL-7 DNA vaccine protect broiler chickens against Coccidiosis

Authors: Panebra, Alfredo; Lillehoj, Hyun

Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2019
Publication Date: 5/1/2019
Citation: Panebra, A., Lillehoj, H.S. 2019. Vaccination with Eimeria tenella elongation factor-1a with IL-7 DNA vaccine protect broiler chickens against Coccidiosis. Avian Diseases. 63:342-350. https://doi.org/10.1637/11976-092418-Reg.1.
DOI: https://doi.org/10.1637/11976-092418-Reg.1

Interpretive Summary: Multiple challenges confront the rising demand for poultry food products, including governmental restrictions on the use of antibiotic growth promoters, high-density production conditions, waste management, and emergence of infectious pathogens, particularly those that cause intestinal disease. Avian coccidiosis is caused by several distinct Eimeria parasites and is the most significant enteric disease of poultry in terms of economics. Ability to develop new prevention strategies against avian coccidiosis will reduce the use of antibiotics in poultry production. In this paper, ARS scientists identified a protein of Eimeria parasites which induced partial protection against coccidiosis challenge infection. The new antigen is called elongation factor 1 alpha (EF-1a) and it is highly conserved and ubiquitously expressed in all eukaryotic cells, playing a central role in protein synthesis. While the use of Eimeria sp. vaccines has been valuable in reducing the need for in-feed medication in chicken growth, experimental coccidiosis vaccines based upon some recombinant Eimeria proteins have been shown to be effective in model systems of experimental infection. In this study, coccidiosis disease challenge model was used to demonstrate significant effects of EF-1a, and chicken IL-7 DNA vaccine against coccidiosis in broiler chicken. This study demonstrated the usefulness of a co-administration of EF-1a DNA vaccine and host cytokine chIL-7 to induce protective immune response against coccidiosis in broiler chickens.

Technical Abstract: Eimeria sp., the causative agent of Coccidiosis lead economic loses in poultry industry. Multiple challenges confront the rising demand for poultry food products, including governmental restrictions on the use of antibiotic growth promoters and novel feedstuffs, high-density production conditions, waste management and the emergency of infectious pathogens, particularly those that cause intestinal disease. There is little doubt that in-feed antibiotics has dramatically increased the efficiency of commercial poultry production. However, antibiotic usage in chickens has raised concerns regarding chemical residues in poultry food products and has directly led the appearance antibiotic-resistance among avian pathogens. Because Eimeria infection leads to a strong species-specific, protective immune response, vaccination of poultry flocks offers an alternative method of disease control. While the use of Eimeria vaccines has been valuable in reducing the need for in-feed medication in chicken growth. Experimental coccidiosis vaccines based upon recombinant Eimeria genes and proteins have been developed and shown to be effective in model systems of experimental infection. We have explored the use of E. tenella EF-1a and chicken IL-7 DNA vaccine against coccidiosis in broiler chicken. After EF-1a and chIL-7 intramuscular immunization and parasite challenge, disease clinical parameters like body weight gain, lesion score, oocyst shedding, serum antibody response and pro-inflammatory cytokines up-regulation were assessed as vaccination efficacy against infection with E. acervulina. Chickens immunized with EF-1a and chIL-7, improved ostensible overall clinical disease manifestations (body weight gain, lesion scores, oocyst shedding, pro-inflammatory cytokines gene expression). Since, it is well-established that DNA vaccine mainly activate CD8+ cytotoxic lymphocytes and its well-known IL-7 action on survival, proliferation and stimulation of CD8+ T-cell lymphocytes, we think that CD8+ cytotoxic T-cell lymphocytes was the main effector of chicken cellular immune response. This study demonstrated the usefulness of Eimeria's antigen (EF-1a) DNA vaccine co-administered with host cytokine (chicken IL-7) to improve and targeted specific T-cell effector lymphocytes against coccidiosis in broiler chickens.