Molecular characterization of MHC class II region in guinea fowl

1. The MHC class II gene was amplified, cloned and sequenced in guinea fowl. 2. The NumeMHC II sequence of 754 nucleotides included complete exon 1 (91 nt), exon 2 (270 nt), exon 3 (282 nt) and exon 4 (110 nt). 3. The size of β(1) and β(2), domains were 89 and 93 amino acids, respectively in guinea fowl. 4. High amino acid variability (38·2%) was observed within guinea fowl in β(1) domain, while in β(2) domain, amino acid variability (6·3%) was low. 5. Among poultry species, the percent amino acid identity between guinea fowl and chicken, quail, pheasant and duck was 38·8, 42·2, 44·4 and 58·8 in β(1) domain; and 13·8, 17·0, 13·8 and 27·6 in β(2) domain, respectively. 6. Sequence alignment with mammalian and avian MHC showed that many of the conserved features of MHC class II glycoprotein was conserved in guinea fowl. 7. Within-species genetic distances (Poisson correction) based on cumulative amino acid variability in β(1) domain and β(2) domains was 0·141 in guinea fowl. 8. Guinea fowl showed low and similar genetic distances with all the poultry species (0·255-0·268) except duck (0·456). 9. Guinea fowl made separate branch within the major cluster having chicken, quail and pheasant, showing equal distance from these poultry species, whereas duck MHC II clustered separately.