Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 28, 1998
Publication Date: N/A
Interpretive Summary: Avian coccidiosis is caused by several intestinal protozoan parasites. Coccidiosis cost poultry industry >$600 million annual loss. Since drug is used to control coccidiosis, new methods of control are needed to enhance food safety. One strategy that ARS scientists are developing depends upon a lymphocyte secreted factor called lymphokine. One of these lymphokines called gamma interferon has been cloned and recombinant gamma interferon inhibited parasite growth in vitro. Furthermore, ARS scientists show for the first time that recombinant gamma-interferon can reduce oocyst production when chickens are injected with this material. These results indicate a potential use of recombinant interferon-gamma in coccidiosis control by poultry industry in the future.
Recombinant chicken interferon-gamma (IFN-g) was produced in CHO-K1 or Spodoptera frugiperda (SF9) insect cells by transfection with a pcDNA vector or baculovirus vector (SF9-IFN-g) carrying the chicken IFN-g gene. Biological activity of recombinant chicken IFN-g was shown by its inhibition of vesicular stomatitis virus-induced cytotoxicity of chicken embryonic fibroblast cells in vitro. To investigate the role of chicken IFN-g during Eimeria infection, CHCC-OU2 chicken fibroblast cells either pretreated with chicken IFN-g or stably transfected with the chicken IFN-g gene were infected with E. Tenella sporozoites. IFN-g demonstrated significant reductions in intracellular sporozoite development without affecting sporozoite invasion of host cells. Furthermore, chickens treated with recombinant chicken IFN-g showed decreased cocyst production and significant improvement in body weight gain following Eimeria challenge infection. These results provide the first direct evidence that chicken IFN-g exerts an inhibitory effect against Eimeria and provides a ratiional basis for use of this cytokine as a vaccine adjuvant against coccidiosis.