Kinetics of replication of primary HIV isolates from LTS and individuals who progressed to AIDS (Progressors). The ability of primary HIV isolates from 6 LTS (A) and 6 Progressors (B) to replicate in PHA-stimulated PBMC of HIV seronegative donors was evaluated over a 2-week period. The PBMC were infected with 100 TCID₅₀ of virus, and replication of virus was indicated by the level of reverse transcriptase activity in the culture fluids.20