Molecular cloning of a feline leukemia provirus integrated adjacent to the c-myc gene in a feline T-cell leukemia cell line and the unique structure of its long terminal repeat.

This paper reports the molecular cloning of a rearranged c-myc region from the FT-1 cell line, which was derived from a spontaneous feline T-cell leukemia carrying the feline leukemia virus (FeLV). An abnormal c-myc EcoRI fragment of about 18 kilobases, detected by Southern blotting, was molecularly cloned from the DNA of the FT-1 cell line. The c-myc rearrangement in FT-1 was due to direct integration of the FeLV provirus genome immediately upstream of the c-myc gene in the opposite transcriptional orientation. Nucleotide sequencing showed that the LTR of this provirus had three copies of an enhancer-like sequence, unlike the sequences of FeLVs reported previously, which have only a single copy of this enhancer-like sequence.