FIG. 2.

RNase protection assay of influenza C virus M gene-derived mRNAs in infected and M gene-transfected cells. (A) Total RNA was extracted from COS-1 and 293T cells infected with C/Yamagata/1/88 at an MOI of 10 PFU/cell at 24 h p.i. (lane Infect) and from cells transfected with pME18S-CM at 48 h p.t. (lane M gene) and analyzed by RNase protection assay using a ³³P-labeled influenza C virus RNA segment 6 (M gene)-specific RNA probe (vRNA sense). The protected fragments were separated on a 4% polyacrylamide gel containing 4 M urea. The HaeIII digest of ψX174 DNA was 5′ end labeled and used as a size marker (marker lane). The probe lane shows an undigested probe. (B) The ratios of 5′ spliced M mRNA to unspliced M mRNA in infected (open box) and transfected (closed box) COS-1 and 293T cells were calculated after densitometry of panel A.