While the effective use of antibiotics for the control of human disease has
saved countless lives and has increased life expectancy over the past few
decades, there are concerns arising from their usage in Livestock. The use
of antibiotic feed additives in food production animals has been linked to
the emergence in the food chain of multiple drug-resistant bacteria that ap
pear impervious to even the most powerful antimicrobial agents. Furthermore
, the use of chemical antimicrobials has led to concerns involving environm
ental contamination and unwanted residues in food products. The imminent ba
nning of antibiotic usage in livestock feed has intensified the search for
environmentally-friendly alternative methods to control disease. Cytokines,
as natural mediators and regulators of the immune response, offer exciting
new alternatives to conventional chemical-based therapeutics. The utilisat
ion of cytokines is becoming more feasible, particularly in poultry, with t
he recent cloning of a number of avian cytokine genes. Chickens offer an at
tractive small animal model system with which to study the effectiveness of
cytokine therapy in the control of disease in intensive livestock. In this
report we will review the status of avian cytokines and focus on our recen
t studies involving the therapeutic potential of chicken interferon gamma (
ChIFN-gamma) as a vaccine adjuvant and a growth promoter. (C) 2000 Elsevier
Science Ltd. All rights reserved.