Abstract:

【Objective】 Comparative analyses were conducted employing the coding sequences of the CD3ε, CD4, and CD8α genes from ducks of certain Chinese domestic breeds, which provide a fundamental basis for the investigation of their structure and function, and potential application of related antibodies. 【Method】 The complete coding sequences of CD3ε, CD4, and CD8α of Sheldrake and Cherry Valley ducks were isolated by RT-PCR assay, and sequence alignment was made employing ClustalX(1.83) and DNAstar software by aligned with the corresponding coding sequences of Pekin duck (published in the GenBank, and accession no: AF378704, AF378701 and AF378373). 【Result】 The identities of pair-wise nucleotide and amino acid sequences of CD3ε and CD4 genes have reached to 99% among Pekin duck, Sheldrake and Cherry Valley duck. As for CD8α, the nucleotide sequences similarities between Pekin duck and Sheldrake reached 99%, whereas it was 95% for Pekin duck and Cherry Valley duck. Furthermore, the amino acid sequence of CD8α is the same for both Sheldrake and Cherry Valley duck, whereas the protein sequence of CD8α of Cherry Valley duck contained 16 different amino acids, including 15 amino acids in the extracellular area, which result in the obvious differences in protein hydrophilicity, antigenicity and the possibilities to be exposed on protein surface.The phylogenetic and evolutionary relationships of the nucleic acid sequences of these genes were analysed, the result showed a close relationship among Cherry valley duck ,Sheldrake and Pekin duck in genes coding for CD3ε and CD4, but Cherry valley duck had a remote relationship with Sheldrake and Pekin duck in genes coding for CD8α. 【Conclusion】 There is a low diversity among Cherry valley duck ,Sheldrake and Pekin duck in genes coding for CD3ε and CD4, but Cherry valley duck has a considerable diversity with Sheldrake and Pekin duck in genes coding for CD8α.

Key words: CD3ε, CD4, CD8α, sequence analyses, sequence identity