Cloning and Sequence Analysis of Caprine Interleukin-10 Gene

Interleukin-10 (IL-10) plays an important role in facilitating development of T helper-2 (Th2) type of immune responses by inhibiting development and progression of Th1 type immune responses. Major reports on IL-10 come from studies in mouse and human models however IL-10 in ruminants is not well investigated, particularly in caprine species. In the present study, gene encoding IL-10 in caprine species was isolated from peripheral blood cells and and sequenced. Caprine IL-10 gene showed 98.9%, 96% and 86.5% similarity with ovine, cattle and human IL-10 gene at the nucleotide level, respectively. At the amino acid level 98.1%, 93% and 79.7% similarity was observed between caprine IL-10 sequence and ovine, cattle and human IL-10 sequence, respectively. There were three amino acid substitutions in caprine IL-10 polypeptide when compared to ovine IL-10 polypeptide (NM1009327). Caprine IL-10 sequence was found to contain 6 alpha-helix structures with 4 cysteine residues that participate in disulphide bond formation. A Phylogenetic tree was constructed based on caprine IL-10 protein sequence. The results suggest that goat IL-10 gene is closely related to small and large ruminants than to monogastric animals.