Figure 1

Absence of K111 5′ end in the genome of some cell lines. (A) Genomic structure of the K111 provirus. Arrows indicate the position of the primers P1 and P4, which amplify the 5′ integration of K111, and the primer/probe combination K111F, K111R, and K111P that specifically discriminates the K111 and K222 env gene from other HERV-K (HML-2) env sequences due to a 6 bp mutation [10]. (B) Detection of K111 5′ end insertions in human cell lines. The 5′ flanking K111 insertions were detected in all human cell lines tested in this study by PCR using the primers P1 and P4 [10], except for the DNA of cell lines H9, HUT78, H9/HTLVIII, and the IRA B-cell line. Arrows indicate individual K111 insertional polymorphisms. Integrity of the DNA was assessed by amplification of GAPDH (see lower gel). The molecular size of the DNA ladder is shown on the left of the gel. On top of each lane is the name of each cell line subjected to study. The weak bands observed in H9 and H9/HTLVIII were shown by sequencing to be the result of non-specific PCR amplification.