Figure 2.

Effect of Rev and Rex expression constructs on virus stock production by packaging and gene-transfer vectors containing the HIV-1 or SIV RREs. Vector stocks were produced using various combinations of packaging and gene transfer vectors containing either HIV-1 or SIV RREs as shown. SIV 1045 or SIV 272 refers to the length of SIV RRE present in the packaging construct or gene transfer vector. The effect of expression of Rev-like proteins from HIV-1 (pCI-HIV-Rev), SIV (pCI-SIV-Rev) and HTLV-1 Rex (pBCRex-1) on vector stock production was tested with each of the combinations. A control vector, pCI-Neo, was used in parallel. The mean vector titers, shown in the top panel, were calculated from % GFP positivity determined by flow cytometry. The bottom panel depicts mean p24 levels in the vector containing supernatants. The titers and p24 levels were normalized to SEAP activity present in the vector stock. Error bar = 1 SD. IU: infectious units. '*' denotes relatively high p24 levels with respect to titer (described in greater detail in the text).