RECOMBINANT CHICKEN INTERFERON-GAMMA-MEDIATED INHIBITION OF EIMERIA-TENELLA DEVELOPMENT IN-VITRO AND REDUCTION OF OOCYST PRODUCTION AND BODY-WEIGHT LOSS FOLLOWING EIMERIA-ACERVULINA CHALLENGE INFECTION

Recombinant chicken interferon-gamma (chIFN-gamma) was produced in CHO -K1 or Spodoptera frugiperda (SF9) insect cells by transfect ion with a pcDNA vector or recombinant baculovirus (SF9-interferon-gamma [IFN-g amma]) carrying the chIFN-gamma gene. A rabbit antibody against a synt hetic peptide corresponding to an immunogenic portion of chIFN-gamma r ecognized a 22-23-kDa band in SF3-IFN-gamma cell extracts by western b lot analysis. Biological activity of recombinant chIFN-gamma was shown by its inhibition of vesicular stomatitis virus-induced cytotoxicity of chicken embryonic fibroblast cells in vitro. To investigate the rol e of chIFN-gamma during Eimeria infection, CHCC-OU2 chicken cells eith er pretreated with chIFN-gamma or stably transfected with the chIFN-ga mma gene were infected with Eimeria tenella sporozoites. IFN-gamma dem onstrated significant reductions in intracellular sporozoite developme nt without affecting sporozoite invasion of host cells. Furthermore, c hickens treated with recombinant chIFN-gamma showed decreased oocyst p roduction and significant improvement in body weight gain following Ei meria acervulina challenge infection. These results provide the first direct evidence that chIFN-gamma exerts an inhibitory effect against E imeria and provides a rational basis for use of this cytokine as a vac cine adjuvant against coccidiosis.