The emerging role of avian cytokines as immunotherapeutics and vaccine adjuvants

The use of antibiotic feed additives and chemical antimicrobials in food production animals is a double-edged sword. On one hand, it helps to prevent the outbreak of disease and promotes the growth of animals, but on the other hand, concerns are mounting over the emergence of antibiotic-resistant bacteria. As a consequence, some countries have already banned the use of in-feed antibiotics which has resulted in meat producers urgently seeking environmentally friendly alternative methods to control disease. Cytokines are proteins that control the type and extent of an immune response following infection or vaccination. They therefore represent excellent naturally occurring therapeutics. The use of cytokines in poultry has become more feasible with the discovery of a number of avian cytokine genes. Since the immune system of chickens is similar to that of mammals, they offer an attractive model system to study the effectiveness of cytokine therapy in the control of disease in livestock. This review will focus on the recent advances made in avian cytokines, with a particular focus on their assessment as therapeutic agents and vaccine adjuvants.