FIG. 4.

Viral RNA synthesis in L-929 cells. L-929 cells were infected with WT GDVII (G) or dl-L (▵) at an MOI of 5 and incubated at 37°C. At 8 h p.i., cytoplasmic RNA was extracted and purified as described in Materials and Methods. Amounts of RNA used in each analysis were derived from set numbers of cells, as indicated above the pairs of lanes. RNA from mock-infected cells (lane M) was used as a control. (A) Extracted RNA was subjected to a two-cycle RNase protection assay for the detection of negative strands as described in Materials and Methods. Lane P, starting probe; lane t, tRNA. (B) Lower amounts of the same RNA preparations were used to probe for positive strands of viral RNA by using a negative-strand probe as described in Materials and Methods.