CD4 and infection: HeLa-CD4 cells transfected with HDAC1 siRNA (Hs_HDAC1_5) or a non-related control siRNA (GFP-22 siRNA) were infected with HIV-1 NL4–3 and replication was monitored for 8 days by quantification of the p24 viral protein in cell supernatants at day 1, 2, 3, 5 and 8 post-infection (pi).