Analysis of particle production and infectivity in MON cells: A. Graphic representation of p24 antigen release (pg/ml) in the culture supernatants of 293T (■) and MON (□) cells transfected with three plasmid based HIV-1 vectors (average of 3 independent experiments). B. Graphic representation of infectivity of virions, normalized for p24, produced in either 293T (■), or MON (□). Both 293T and MON cells were infected with these two sets of virions (average of 3 independent experiments). C. Schematic representation of 2 blocks in HIV-1 replication in MON cells. 1st block exists at the level of virus particle production and the 2nd block exists at the level of infectivity. D. Schematic representation of a block in HIV-1 replication in STA-WT1 cells at the level of virus particle production.