Infectivities of replication-competent viruses carrying highly macrophage-tropic and non-macrophage-tropic envelopes evaluated on HeLa TZM-BL cells, primary macrophages, PBMCs, and CD4+ T cells. A. Infectivity titers of replication-competent viruses carrying macrophage-tropic (YU2, NA20 B59, and NA420 B33) or non-macrophage-tropic (JR-CSF, NA420 LN85, and NA118 LN33) envelopes. Infectivities for HeLa TZM-BL cells and macrophages were estimated by FFU assays, and the results shown represent averaged FFU counts for duplicate wells from one of several experiments with similar results. Infectivities for PBMCs and CD4+ T cells were estimated by TCID50 assay, using replicates of six wells, and are representative of at least two experiments. B. Ratios of infectivity for macrophages compared to HeLa TZM-BL cells, PBMCs, and CD4+ T cells. C. Ratios of infectivity for macrophages, PBMCs, and CD4+ T cells compared to HeLa TZM-BL cells.