FIG. 2.

Saturable packaging and transduction of reporter vRNA. (A) Dose-dependent expression of reporter transcripts. 293T cells were transfected with the indicated amounts of NP-Y reporter vector along with either all 17 standard plasmids (at left) or all except the wild-type (wt) NP vRNA vector (at right). Cellular RNA harvested 48 h posttransfection was probed for positive-sense reporter transcripts (mRNA and cRNA) by RPA. Control cells were transfected either with a GFP-mRNA expression vector (EGFP-N1) or with pHH21. (B) Virions isolated from supernatants of the same cells (whose transfections included the wild-type NP vRNA vector) were assayed for MDCK-transducing activity at 10 h postinfection by flow cytometry. (C) Total plaque-forming activities of the supernatants in panel B, assayed in MDCK monolayers.