Organization of the class I region of the bovine major histocompatibility complex (BoLA) and the characterization of a class I frameshift deletion (BoLA-Adel) prevalent in feral bovids
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The major histocompatibility complex (MHC) is a genomic region containing genes of immunomodulatory importance. MHC class I genes encode cell-surface glycoproteins that present peptides to circulating T cells, playing a key role in recognition of self and non-self. Studies of MHC loci in vertebrates have examined levels of polymorphism and molecular evolutionary processes generating diversity. The bovine MHC (BoLA) has been associated with disease susceptibility, resistance and progression. To delineate mechanisms by which MHC class I genes evolved to function optimally in a species like cattle, it is necessary to study genomic organization of BoLA to define gene content, and investigate characteristics of expressed class I molecules. This study describes development of a physical map of BoLA class I region derived from screening two BAC libraries, isolating positive clones and confirming gene content, order and chromosomal location through PCR, novel BAC end sequencing techniques, and selected BAC shotgun cloning and/or sequencing and FISH analysis. To date, this is the most complete ordered BAC array encompassing the BoLA class I region from the class III boundary to the extended class I region. Characterization of a frameshift allele exhibiting trans-species polymorphism in Bos and Bison by flow cytometry, real-time RT-PCR, 1D and 2D gel analysis is also described. This frameshift allele encodes an early termination signal within the antigen recognition site (ARS) of exon 3 of the BoLA BSA-Adel class I gene predicting a truncated class I protein that is soluble. An ability to assess MHC diversity in populations and provision of animals with defined MHC haplotypes and genetic content for experimental research is necessary in developing a basis upon which to build functional studies to elucidate associations between haplotype and disease in bovids. The BoLA class I region is immunologically important for disease association studies in an economically important species. This study provides knowledge of gene content and organization within the class I MHC region in cattle, providing a template for more detailed analysis and elucidation of complex disease associations through functional genomics and comparative analysis, as well as evolution of the MHC in bovids to optimize a populationÂs immune response.
Ramlachan, Nicole (2004). Organization of the class I region of the bovine major histocompatibility complex (BoLA) and the characterization of a class I frameshift deletion (BoLA-Adel) prevalent in feral bovids. Doctoral dissertation, Texas A&M University. Texas A&M University. Available electronically from