FIG. 4.

Cellular gag RNA levels and vif mRNA splicing of the wild-type control and deletion mutants in transfected FOS cells. (A) Levels of gag RNA, as measured by real-time qRT-PCR using gag RNA-specific primers. Measurements were normalized for ovine β-actin mRNA expression. Values are expressed as copy numbers of gag RNA per 100 copies of β-actin mRNA. Means with standard errors for at least three independent experiments are shown. (B) RT-PCR products of vif mRNA visualized after electrophoresis in 1.7% agarose. Splicing of the MSD to the splice acceptor for vif mRNA generated a 356-bp product for the wild type and for mutants with deletions located downstream of the MSD, but for the upstream mutants ΔSL1, ΔSL2, Δ5MSD, and DM, the products were expected to be 334, 336, 256, and 256 bp, respectively.