The Biological Significance of Cellular Alloantigen Systems in Captive Avian Populations

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The overall objective of this research is to apply immunogenetic knowledge already acquired in the domestic fowl toward preserving the genetic health of captive avian species, especially those in danger of extinction. In the chicken there are 12 genetic loci or gene complexes producing antigens on erythrocytes and, more recently some five additional loci determining lymphocyte specificity have been discovered in this laboratory. These genetic systems of polymorphic genes are potentially beneficial in several respects. Some of the gene systems have distinct physiological effects. The B system is the major histocompatibility complex (MHC) of the chicken and is of prime significance in both humoral and cellular immune response. The B system serves as an example of a multi-gene complex in which individuals inheriting two different B gene complexes are at a survival advantage because of more effective immune defense. The other more highly polymorphic systems are to be examined for specific effects on survival under exposure to naturally occurring diseases. Other systems encoding lymphocyte antigens are known to interact with the MHC in the overall immune response to environmental stimuli. The unique genetic stocks and reagents developed for specific immunogenetic objectives make possible interdisciplinary research with colleagues in related areas--restriction fragment length polymorphisms, natural resistance to environmental disease organisms, genome mapping, and the use of alloantigen gene systems as markers in monitoring individual fitness. Finally, studying these multigene systems in avian populations over time will enhance our understanding of their function in the evolution of birds. This research will apply immunogenetic knowledge obtained from study of chickens to develop new knowledge of the immunological recognition systems of several wild bird species which currently exist in very limited numbers. This will be done by identifying, on the surfaces of red and white blood cells, specific families of molecules involved in immune recognition. An immediate practical benefit of being able to identify the immunological recognition systems in captive bird species is their use in a simple blood test to check pedigree information to avoid accidental mating of closely related individuals, and thus to maximize the genetic diversity of small populations. This information will contribute to our ability to preserve the genetic health of captive bird species, especially those in danger of extinction.