Submitted to: Diseases of Poultry
Publication Type: Book / Chapter
Publication Acceptance Date: 1/3/2007
Publication Date: 6/20/2008
Citation: Cheng, H.H., Lamont, S.J. 2008. Genetics of disease resistance. In: Saif, Y.M., Fadly, A.M., Glisson, J.R., McDougald, L.R., Nolan, L.K., Swayne, D.E., editors. Diseases of Poultry. 12th edition. Ames, IA: Iowa State University Press. p. 59-72.
Technical Abstract: Genetic resistance is alluring from both the industrial and academic viewpoints. With respect to poultry companies, losses due to diseases induced by infectious pathogens continue to be a significant issue and can be the key factor in determining economic viability. This is because pathogens lead to loss or condemnation of birds, inhibit the immune response making birds susceptible to other pathogens and diseases, divert critical resources from growth and production, add expenses for vaccination programs, and force changes in husbandry practices, all of which increase the cost of production. From the academic side, modern molecular genetics has provided an arsenal of new tools for identifying disease resistance genes. As a component of genomics, there is great excitement that some of the complexity of biology, and in particular the immune response, may finally become fully elucidated. It is reasonable to expect that genetics will identify genes, or at least genomic regions containing these genes (known as QTL or quantitative trait loci) that control complex traits like disease resistance. It is also expected that information will be forthcoming on how these genes function and interact as well as respond to changing environments to control disease. Ultimately, this information will be transferred to poultry companies to generate elite lines with superior disease resistance or better vaccinal response. In this section, we focus on recent advancements in genetic resistance to disease, namely, molecular and quantitative genetics. The targeted audience is animal health professionals and others that may not be familiar with molecular or quantitative genetics. We hope to convey the high level of excitement (as well as limitations) in these areas, which has been brought about with the recent release of the chicken genome sequence and other related technologies. To achieve these goals, sections are presented on (1) a review of genetic concepts necessary for a basic understanding, (2) molecular genetic approaches to identify disease resistance genes, (3) complementary functional genomic approaches that provide insights on the biochemical mechanisms and pathways of disease resistance, (4) brief summaries of genetic resistance and experimental studies for specific diseases, and (5) thoughts on how this information may be applied in poultry breeding to improve host resistance to infectious disease. The emphasis throughout these sections is on basic concepts as given the short history and dynamics of the field, knowledge and state-of-the art methods will change rapidly. Finally, some topics of general interest (e.g., the chicken genome assembly, use of molecular genetic tools for veterinary diagnostics) are briefly discussed as general interest or tools that could be transferred to veterinary diagnostics.