Molecular cloning of a novel interferon regulatory factor in Japanese flounder, Paralichthys olivaceus

A complementary DNA library was constructed in lambda ZAP II using messenger RNA from the leukocytes of some heterocloned Japanese flounder, Paralichthys olivaceus, that had been artificially infected with Hirame rhabdovirus (HRV). A cloned flounder interferon regulatory factor (designated fIRF) cDNA was found to be 1746 bp in length, with an open reading frame of 297 amino acids. The overall amino acid sequence of fIRF had approximately 40% identity with the previously reported avian and mammalian IRF-1s and IRF-2s. The fIRF sequence was most similar to that recorded for the chicken IRF-1. Amino acid sequence identities between the DNA-binding domain of the fIRF and that of both chicken IRF-1 and chicken IRF-2 were 72.3%. The DNA-binding domain of fIRF contained the repeated tryptophan motif that is characteristic of members of the IRF family. The mRNA of fIRF was detected in various tissues by reverse transcription-polymerase chain reaction (RT-PCR).