Submitted to: World Poultry Congress Proceedings
Publication Type: Proceedings
Publication Acceptance Date: June 1, 2001
Publication Date: N/A
Interpretive Summary: Coccidiosis is a major protozoan disease seriously impairing the feed utilization and growth of chickens. Because natural infection with Eimeria is self-limiting and induces long-lasting protective immunity, vaccination against coccidiosis is probably feasible although the success of any vaccine will ultimately depend upon comprehensive understanding of host immunity both at the cellular and molecular levels. In this paper, ARS scientist showed that chicken cytokines such as IL-2 and IFN-gamma enhance the effect of recombinant vaccination against coccidiosis. Vaccination of chickens with a recombinant protein expressed on the surface of coccidia induced partial protection against live challenge infection with E. acervulina. Furthermore, co-injection of recombinant protein with chicken cytokines such as IL-2 or IFN-gamma further enhanced host immunity. These results will facilitate the development of novel immunological control strategy against coccidiosis.
A rabbit antiserum against an 18 - 27 kDa native protein fraction (F3) from E. acervulina merozoites identified a cDNA (3-1E) containing a 1,086 base pair insertion with an open reading frame of 170 amino acids. A rabbit antiserum against a synthetic peptide deduced from the amino acid sequence of the 3-1E cDNA reacted with a 27 kDa recombinant 3-1E protein expressed in Sf9 insect cells and a 20 kDa native protein expressed by E. acervulina sporozoites and E. tenella sporozoites and merozoites. Spleen lymphocytes from E. acervulina immune chickens showed antigen specific proliferation and IFN-g production upon stimulation with the recombinant 3-1E protein indicating that it activates cell mediated immunity during coccidiosis. Immunization of chickens with either the E. coli or Sf9 expressed recombinant 3-1E protein, or direct injection of the 3-1E cDNA, induced protective immunity against live E. acervulina. Simultaneous injection of the recombinant 3-1E protein, or the 3-1E cDNA, with cDNAs encoding chicke IFN-g or IL-2/15 further enhanced protective immunity. These results indicate that the recombinant E. acervulina 3-1E cDNA or its polypeptide product may prove useful as vaccines against avian coccidiosis.