CDNA Cloning And Genomic Structure Of The Duck (Anas Platyrhynchos) MHC Class â…  Gene

In order to provide data for studies on the duck MHC, a pair of degenerate primers according to MHC class I alignment of human, mouse, chicken and etc. was designated to amplify a fragment of the duck MHC class I (Anpl-MHC I) a 2 domain. Based on the known sequence, Anpl-MHC I cDNA was cloned with the methods of 3' -RACE and cDNA PCR Library, and the genome structure was investigated. Anpl-MHC I genes encoded 344-355 amino acids. The genomic organization is composed of eight exons and seven introns. Based on the genetic distance, Anpl-MHC I cDNA from six individuals can be classified into four lineages (from Anpl-UAA to Anpl-UDA). A total of 28 amino acid positions in the PBD (peptide-binding domain) showed high scores by Wu-kabat index analysis. The Anpl-MHC amino acid sequence displayed seven critical HLA-A2 amino acids that bind with antigen polypeptides, and have an 83.6%-88.5% amino acid homology with each lineages, a 55.2% - 64.6% amino acid homology with chicken MHC class I (B-FIV21, B-FIV2, Rfp-Y), and a 40.3% - 42.8% homology with mammalian MHC class I. Among birds, frog and fish species, Anpl-MHC I amino acid is more similar to the human MHC class I (HLA-A2). Compared with the human HLA-A2 tertiary structure of the PBD, Anpl-MHC I had an insertion or deletion variation in four domains (A-D). The phylogenetic tree appear to branch in an order consistent with accepted evolutionary pathways. Nested-PCR detection show that Anpl-MHC I can be expressed in the brain, heart, kidney, intestines and bursa The research provided the data for the further studies on disease resistance.