Decreased cellular HAP95 does not affect the production of HIV-1 particles, but reduces the infectivity of virus particles. 293 T cells were treated with siRNACon or siRNAHAP, and 16 hours later, were transfected with DNA encoding for HIV-1 BH10. (A) Cell lysates were prepared at 24 hours posttransfection of DNA and analyzed by Western blotting using anti-HAP95, anti-RHA, or anti-β-actin. (B) The extracellular culture medium was analyzed by CAp24 ELISA assay at the indicated time points posttransfection of DNA to determine the amount of virus particles. (C) Viral infectivity assay. HIV-1 particles were purified at 48 hours posttransfection of DNA and the single-round viral infectivity was measured by challenging TMZ-b1 cell with purified viruses corresponding to 5 ng of CAp24. The induced luciferase activity was determined at 24 hours later and the results were normalized to that of virions produced from siRNACon-treated cells. Shown are the mean values ± standard deviation (SD) of results of 3 experiments. *, P <0.05.