Figure 5.

Synthesis of IVa2 and pTP/Polymerase mRNAs during infection by wild-type and pTP deletion mutant viruses. RNA samples isolated from 293 or 293-pTP₄₀ cells at various times after infection with either dl308_ΔpTP or dl309 as indicated above the lanes were assayed by RNase protection for the presence of IVa2 mRNA. The antisense probe consists of the sequence between the XhoI site at bp 5788 and the BstEII site at bp 5186 and overlaps both the pTP and DNA polymerase mRNAs and IVa2 mRNA as schematically indicated above. IVa2 mRNA contains an intron, indicated by the gap, that is not removed from the E2B mRNAs. An autoradiograph of the gel is presented below with the protected species indicated. The fragment protected by the 5′ exon of IVa2 mRNA migrated to the bottom of the gel and is excluded. An overexposure of the lanes containing mRNAs from 293-pTP₄₀ cells infected with dl308_ΔpTP and 293 cells infected with dl309 is presented so that the pTP+DNA pol band present in 293 cells infected with dl308_ΔpTP is apparent.