FIG. 4.
Infectivities of three HIV-1 strains in JC clones and PBMCs. M-tropic HIV-1 strain JR-CSF and Ba-L and T-tropic HIV-1 NL4-3 were used to infect nine HeLa-CD4/CCR5 JC clones with differing levels of CCR5 expression, as well as the CCR5-negative CD4-positive parental clone HI-J and PBMCs. JC clones with CCR5 expression ranging from 2 × 103 to 1.3 × 105 molecules/cell gave similar titers for the two M-tropic strains. In contrast, HI-J was negative and clone JC.20, with background CCR5 expression (<7 × 102 molecules/cell), had markedly reduced titers. Although M-tropic HIV-1 did not infect HI-J cells, titers are indicated as <5 to account for the virus dilutions used in the assays. Titers in PBMCs expressed as TCID50/0.05 ml were numerically similar to titers (foci/0.05 ml) seen on the highly sensitive JC clones.