Molecular cloning, phylogenetic analysis and expression of beluga whale (Delphinapterus leucas) interleukin 6

Interleukin 6 (IL-6) is a cytokine produced primarily by the monocytes/macr ophages with regulatory effects in hematopoiesis, acute phase response, and multiple aspects of the immune response. IL-6 exerts its activity through its binding to specific high affinity receptors at the surface of target ce lls. As yet, no molecular data have been reported for the beluga whale IL-6 . In this study, we cloned and determined the entire beluga whale IL-6-enco ding cDNA sequence by reverse transcription-polymerase chain reaction (RT-P CR) sequencing, and analysed its genetic relationship with those from sever al mammalian species including human, rodent, ruminant, carnivore and other marine species. The identity levels of beluga whale IL-6 nucleic and deduc ed amino acid sequences with those from these mammalian species ranged from 62.3 to 97.3%, and 42.9 to 95.6%, respectively. Phylogenetic analysis base d on amino acid sequences showed that the beluga whale IL-6 was most closel y related to that of the killer whale. Thereafter, beluga whale IL-6-encodi ng sequence was successfully expressed in Escherichia coli by using the pTH IOHisA expression vector for the production of a recombinant fusion protein . The immunogenicity of the recombinant fusion protein was then confirmed a s determined by the production of a beluga whale IL-6-specific rabbit antis erum. (C) 2000 Elsevier Science B.V. All rights reserved.