Submitted to: Veterinary Immunology and Immunopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 5, 1997
Publication Date: N/A
Interpretive Summary: Avian coccidiosis is a major parasitic disease of poultry which costs the industry greater than $600 million annual loss due to medication. Ability to vaccinate against coccidiosis, will have a major impact on world-wide industry. In this report, ARS scientists genetically engineered a chicken cytokine which can be used in the future control of coccidiosis. The results show that recombinant chicken cytokine activates immune system. Further characterization on this cytokine will lead to a better strategy against coccidiosis.
Chicken cDNA encoding interferon-gamma (IFN-g) was cloned from CD4+ chicken T-cell hybridoma by reverse transcription-polymerase chain reaction (RT-PCR) and expressed in Escherichia coli, COS-7 and CEC- 32 chicken fibroblast cell lines. In general, recombinant IFN-g (rIFN-g) which is expressed in the COS-7 and CEC-32 cell lines showed higher bioactivity in vitro. The kinetics of IFN-g mRNA and gene expression was examined in concanavalin A (Con A)-activated spleen lymphocytes by Northern blot and RT-PCR. IFN-g mRNA was detected as early as 30 min after Con A activation and peaked 2 hr (and then decreased starting at 4 hr) post Con A activation. Rabbit serum made to a synthetic peptide of IFN-g immunoprecipitated a 60 kDa molecule of E. coli maltose-binding protein fusion protein of rIFN-g (MBP-IFN) and a 26-27 kDa secreted rIFN-g expressed in COS cells and in conditioned medium prepared from Con A-activated spleen cells. The chicken rIFN-g inhibited vesicular stomatitis virus (VSV)-mediated cytotoxity of chicken embryonic fibroblast (CEF) cells and upregulated the expression of many macrophage cell surface antigens including the class I and class I major histocompatibility complex (MHC). These results show that chicken rIFN-g possesses anti-viral activity and immunoregulates macrophage activities.