TEMPORAL GENE-REGULATION OF THE CHANNEL CATFISH VIRUS (ICTALURID HERPESVIRUS-1)

To identify promoter regions that impart differential temporal regulat ion of channel catfish virus (CCV) genes, the transcriptional kinetics of an immediate-early gene and prospective early and late genes were characterized, A cDNA clone, designated IE3C, representing a third imm ediate-early transcript was identified. The 5' end of the IE3C transcr ipt was mapped to nucleotides 15,368 and 131,043 in the terminal repen t regions of the CCV genome, The full length of the transcript represe nted by the IE3C clone is 1,412 bp, and it most likely codes for the p rotein specified by open reading frame (ORF) 12. The putative product of ORF12 contains a consensus RING finger metal binding motif (C3HC4 s tructure), Temporal expression studies, in conjunction with protein sy nthesis and DNA replication inhibition, demonstrated that the IE3C tra nscript belongs to an immediate-early kinetic class, the ORF5 transcri pt is a member of the early kinetic class, and ORF39 and ORF46 are tru e late-kinetic-class genes, Additionally, we demonstrated that ORF38 t ranscription overlaps ORF39 and the products presumably share the same poly(A) signal, The 5' ends of the transcripts encoding ORF38, ORF39, and ORF46 were mapped to nucleotides 44,862, 45,254, and 59,644, resp ectively, and potential transcriptional control elements were located.