Type 1 HERV-K genome is spliced into subgenomic transcripts in the human breast tumor cell line T47D.

Two types of HERV-K genomes exist which differ in the absence (type 1) or the presence (type 2) of a sequence of 292 nucleotides between the putative pol and env genes. Previously published results from teratocarcinoma cell studies had firmly concluded that the type 1 HERV-K genome was defective in splicing and that only the nondeleted type 2 HERV-K genome containing the 292-nucleotide sequence was capable of being spliced. We now show that in the T47D human breast tumor cell line it is the type 1 HERV-K genome, and not the type 2, which is spliced to subgenomic transcripts.