NE060: Genetic Bases for Resistance and Immunity to Avian Diseases
Statement of Issues and Justification
The economic importance of disease to chicken production (both layers and broilers) is difficult to estimate as costs are not only direct (mortality and morbidity) but indirect as well (vaccinations, chemotherapy, and eradication programs). Annual economic losses in the United States alone are estimated in the billions. Vulnerability to disease also may threaten U.S. domestic supplies as well as exports of this important food commodity.It is now clear that the genetic constitution of the specific strain of chicken stocks being produced is a major determinant of the bird's immune response to pathogens. Much of this understanding is based on studies of the chicken MHC, but other gene loci are also known to be important. In addition, the chicken's ability to mount an immune response is strongly influenced by non-genetic factors and relatively little is known about interactions between genetic and non-genetic factors. Preliminary evidence that certain genetic strains exhibit diverse responses to different vaccines against Marek's disease suggests that genetic constitution of the chicken host could also be of strategic importance in vaccine development. Genetically-engineered vaccines tailored not only to the disease agent but to the chicken strain itself may be typical of vaccines in the future.
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