Effect of CypA knock-down on SIV and HIV-1 replication in human CEM-SS cells. (A) The amounts of viral cDNA synthesized after SIVagm (left panel), SIVmac239 (middle panel) or HIV-1 (right panel) infection. Viruses produced from CEM-SS cells were used to infect CsA-untreated or CsA-treated target CEM-SS, CypA-KD cells. Heat-inactivated virus was used as an infection control. The synthesized viral cDNA levels were measured by real-time PCR. Mean values and standard deviations in six independent experiments are shown. Relative viral cDNA levels are shown as the ratio (%) of the viral cDNA levels to that of viruses produced from CsA-untreated CEM-SS in CsA-untreated CEM-SS cells. (B) Replication of SIVagm (left panels) or HIV-1 (right panels) in CypA-KD CEM-SS cells. Viral production in normal CsA-untreated CEM-SS (closed circles), CsA-untreated (closed squares) or CsA-treated CypA-KD (open squares) was monitored by measuring RT activity in the culture supernatants.