Identification and genomic organization of K111 proviruses. (A) Quantitation of K111 env titers by qRT-PCR in the plasma of patients with HIV-1 and other diseases. The K111 env titers were measured by qRT-PCR using the probe K111P (see Supplemental Methods) that specifically discriminates the K111 env gene from other HERV-K (HML-2) env sequences due to a 6-bp mutation. K111 titers were detected in the plasma of patients with HIV infection but not in the plasma of healthy individuals or the plasma of patients with lymphoma or breast cancer. (B) Genomic organization of K111 full-length and solo LTR, target site duplication “GAATTC,” and centromeric flanking sequences (CER:D22Z3). Frame shift (FS) and stop codon (asterisks) mutations are indicated. The positions of the primers used to amplify K111 5′ LTR and 3′ LTR insertions are indicated by arrows.