Effect of CypB knock-down on HIV-1 and SIV replication in human CEM-SS T cells. (A) Immunoblot analysis of CypB expression. Lysates of CEM-SS (normal), CypA-KD, and CypB-KD cells were subjected to the immunoblot analysis using anti-α-tubulin, anti-CypA and anti-CypB antibodies (Abcam Inc., Cambridge, MA) (left panel). CypA- and CypB-specific band densities were quantified by densitometric scanning and are plotted in the right panels. The image of one representative blot is shown. (B) Replication of SIVagm (left panels) or HIV-1 (right panels) in CypB-KD CEM-SS cells. Viral production in normal CEM-SS (closed circles) or CypB-KD cells (closed triangles) was monitored by measuring RT activity in the culture supernatants.