Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 1, 2000
Publication Date: N/A
Interpretive Summary: Coccidiosis is a major parasitic disease of poultry which causes >$600 million annual economic loss. Drug resistance of coccidia parasites in the field urges a development of new control strategy against this disease. In this paper, ARS scientists collaborated with scientists at academia and industry to clone a coccidia gene which induces cell-mediated immunity. Furthermore, these scientists demonstrated that the chickens which are vaccinated with this protein showed good level of protective immunity against live coccidiosis challenge infection. This report sets the ground work for future development of novel control strategy against coccidiosis.
cDNA expressed in E. coli produced a 60 kDa fusion protein and a 23 kDa protein after factor Xa treatment of the fusion protein. Both proteins were reactive with the F3 antiserum by Western blot analysis. 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. By immunofluorescence staining, a monoclonal antibody produced against the recombinant 3-1E protein, reacted with sporozoites and merozoites of E. acervulina, E. tenella, and E. maxima. Spleen lymphocytes from E. acervulina immune chickens showed antigen specific proliferation and IFN- gamma production upon stimulation with the recombinant 301E 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 with adjuvant, 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 chicken IFN-gamma or IL-2 further enhanced protective immunity. These results indicate that the recombinant E. acervulina 3-1E cDNA or its polypeptide product may prove useful as vacines against avian coccidiosis.