FIG 3.
Effects of glycoprotein expression levels on specific infectivity of EBOV GP1,2 and HIV Env-pseudotyped viruses. 293T cells were cotransfected with 500 ng of plasmid encoding HIVΔEnv (SG3) backbone plus plasmids encoding GP1,2 from Zaire ebolavirus or HIV Env (SF162). The amounts of glycoprotein-encoding DNA plasmids varied from 4 μg to 4 ng, and pseudovirus infectivity in supernatant was measured at 48 h posttransfection by luciferase assay and converted to PFU/ml as described in Materials and Methods. In parallel, the level of p24 in supernatant was determined by a sandwich ELISA. Based on the obtained results, the specific infectivity of EBOV GP1,2 as well as HIV Env-pseudoviruses, defined as PFU/pg p24, was calculated and plotted versus the amount of transfected GP1,2 or HIV Env DNA, respectively.