Biological characterization of the recombinant viruses.

A) Infectivity of env recombinant viruses in TZM-bl cells. Cells were infected with 15 units of HIV-1 p24 antigen (75 pg) of virus-supernatants. Luciferase activity was measured 48 hours post-infection and the results were normalized to the value obtained with the WT virus (89ES061). Results represented the median and SE of two independent assays with thee replicates. B) Replication kinetics of env recombinant viruses in U87-CD4/CCR5 cells. Cells were infected with 100 units of HIV- 1 p24 antigen (500 pg) of virus supernatants. Cultures were followed during 14 days, and HIV-1 production was quantified by the RT-activity in the supernatant with in-house Syber green I based real-time PCR enhanced RT assay (SGPERT). Cluster’s recombinant viruses (red) were compared with recombinant viruses from chronic progressor patients (green), with a recombinant virus obtained from laboratory strain SF-162 (black), and with the laboratory infectious clone 89ES061 (black) where the nucleotide sequences were cloned.