Genotyping MHC class I loading complex genes (TAP1, TAP2 and Tapasin) for their association with immunocompetence traits in chicken

Abstract

The production, reproduction and health of the animals are mainly influenced by the genetic makeup of the animal along with nutritional and environmental milieu. With the intensive selective breeding in poultry, remarkable progress has made in both egg and meat production traits but this unidirectional selection (either for meat or egg) leads to some undesirable traits like congenital disorders, vulnerability towards many diseases etc. Further, awareness in the food safety there is a need to reduce the use of antibiotic and other chemicals. So, it is desirable to have disease resistant strains along with better genetic amalgamation for useful traits. Disease resistance is a complex trait and the mortality/disease susceptible in poultry is a great concern for economic loss in poultry industry. A potential and sustainable option to reduce or check the diseases in poultry is the genetic selection/ improvement of birds for disease resistance. With natural selection and using traditional selection tools, the genetic gain in the desired traits is slow, difficult to measure and time consuming. Moreover, the heritability of immune traits is also very low in poultry. The differences in genetic response to different diseases have been well established in chickens and selection of chickens which shows better genetic resistance for diseases is an important way to greater disease protection. The selective genotyping will provide an efficient means of achieving desired immune traits that may quickly and cost-effectively provide functional markers for validation and application in poultry molecular breeding programs. The effect of many major genes involved in disease resistance has been intensively studied in farm animals including poultry. However, the other associated genes are equally important for regulating and coordinating the disease controlling process need to be evaluated for their role in disease leading to better understanding of the this complex immune process. Cell-mediated immunity plays an essential role against pathogens particularly against viral infection via presentation of peptides bound to MHC class I molecules to CD8+ cytotoxic T lymphocytes. This presentation, stabilization and translocation of peptide to MHC class I molecules involves various proteins that constituents peptide loading complex (PLC). Therefore, the delineation of the genetic design of the genes involved in the peptide loading complex is an important step towards bird’s selection to accelerate the genetic gain for the disease traits.