Cloning and biological characterization of buffalo (Bubalus bubalis) interferon-gamma.

Interferon-gamma, a major immunomodulatory cytokine, of Indian water buffalo (Bubalus bubalis) was characterized at molecular level. Complementary DNA and essential promoter region were cloned and sequenced, and functional recombinant protein was expressed in bacterial system. The cDNA has 97.8% nucleotide identity with 11-nucleotide and four-amino acid variations, and the essential promoter region has 98.4% identity with five-nucleotide variations and a four-nucleotide deletion in comparison with the corresponding bovine sequences. All the major promoter elements such as NF IL-2 like motif, cyclosporin sensitive binding element and GATA motif are strictly conserved. Recombinant buffalo-IFN-gamma expressed in bacterial system reacted with an anti-bovine-IFN-gamma monoclonal antibody in Western blot and showed antiviral activity against buffalo pox virus in cultured Madin-Darby bovine kidney (MDBK) cells by inhibiting virus induced cytopathic effect. The study shows high level sequence similarity of IFN-gamma among ruminants. In view of the immunomodulatory and antiviral activities of IFN-gamma, this molecule will be useful in better understanding of the immune system of water buffaloes.