Channel catfish, Ictalurus punctatus, cyclophilin A and B cDNA characterization and expression analysis.

The preliminary observation of up-regulation of cyclophilin transcripts during Edwardsiella ictaluri infection prompted us to speculate on the potential importance of cyclophilins in the early stage of infection. To provide a framework for answering these questions, two cyclophilin cDNA of channel catfish, Ictalurus punctatus, were identified, sequenced and characterized. The complete nucleotide sequences of cyclophilin A and cyclophilin B cDNA consisted of 1170 and 996 bases, respectively. Analyses of the sequences revealed each had one open reading frame potentially encoding 164 amino acids with calculated molecular mass of 17,450Da and 216 amino acids with calculated molecular mass of 23,852Da for cyclophilin A and cyclophilin B, respectively. The degrees of conservation of channel catfish cyclophilin A and cyclophilin B amino acid sequences to counterparts of other species ranged from 74 to 84% and 80 to 92%, respectively. Both cyclophilin A and cyclophilin B transcripts were constitutively expressed in all tissues of channel catfish examined in this study. These results provide valuable information not only for further exploring the roles of cyclophilins in fish immune responses to infection, but also for production of polyclonal/monoclonal antibodies for channel catfish cyclophilins.