IN-VIVO EFFECTS OF CHICKEN INTERFERON-GAMMA DURING INFECTION WITH EIMERIA

Newly hatched chickens are highly susceptible to infection by opportun istic pathogens during the first 1 or 2 weeks of life, The use of cyto kines as therapeutic agents has been studied in animal models as well as in immunosuppressed patients, This approach has become more feasibl e in livestock animals, in particular poultry, with the recent cloning of cytokine genes and the development of new technologies, such as li ve delivery vectors, We have recently cloned the gene for chicken inte rferon-gamma (Ch-IFN-gamma), Poly-HIS-tagged recombinant Ch-IFN-gamma was expressed in Escherichia coil, was purified by Ni chromatography, and was found to be stable at 4 degrees C and an ambient temperature f or at least several months and Several weeks, respectively, Ch-IFN-gam ma was capable of protecting chick fibroblasts from undergoing virus-m ediated lysis, induced nitrite secretion from chicken macrophages in v itro, and enhanced MHC class II expression on macrophages, Administrat ion of recombinant Ch-IFN-gamma to chickens resulted in enhanced weigh t gain over a 12-day period, Furthermore, the therapeutic potential of Ch-IFN-gamma was assessed using a coccidial challenge model, Birds we re treated with Ch-IFN-gamma or a diluent control and then infected wi th Eimeria acervulina. Infected birds treated with Ch-IFN-gamma showed improved weight gain relative to noninfected birds, The ability of Ch -IFN-gamma to enhance weight gain in the face of coccidial infection m akes it an excellent candidate as a therapeutic agent.