TAP1 and TAP2 genes code for the two subunits of the transporter associated with antigen processing (TAP), and in chicken they are located between the two MHC class I genes. Using primers based on chicken sequences, the genomic regions corresponding to chicken TAP1 exons 6 to 7 and TAP2 exons 4 to 6 (which encode portions of the chicken TAP1 and TAP2 molecules corresponding to the human peptide-binding regions) were amplified and sequenced from chicken (70 birds), turkey (24), pheasant (6), and

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... guinea fowl (7). A total of 80 within-species single nucleotide polymorphisms (SNPs) were identified. None of the chicken SNPs detected here was present in public databases. The SNP frequencies in chicken were 9.57 SNP/kb in TAP1 and 19.16 SNP/kb in TAP2, while turkey showed similar SNP frequencies in the two genes. Putative amino acid sequences were inferred to identify non-synonymous substitutions.