Proviral load. Genomic DNA was isolated from PBMCs and used in a real-time PCR assay to detect provirus. The average proviral load was 84, 116, 89, and 166 proviral copies per 10,000 PBMCs at 8, 13, 21, and 34 wk post-infection, respectively. ROS1, the negative control, was below the level of detection for the entire length of the study.