NV RNA replicates in 293FT cells. (A) Schematic drawing of NV genome RNA showing viral proteins encoded by each of the three ORFs. (B) Western blotting detection of VPg precursors and VP1 in NV RNA-transfected 293FT cells. Cells were transfected with carrier RNA (−) or NV RNA (+) and incubated for 48 h. Note that mature VPg (20 kDa) was not detectable by Western blotting. Actin and a nonspecific protein band served as equal loading controls. (C) NV VP1 expression is RNA replication dependent. 293FT cells were transfected with in vitro-transcribed NV genomic RNA (NV IVT RNA) or stool-isolated NV RNA and incubated for 48 h. VPg precursors and VP1 in cell lysates were detected by Western blotting. VP1 was concentrated by immunoprecipitation (IP) prior to Western blotting. (D and E) Kinetics of expression of VP1 and NV RNA during NV RNA replication. 293FT cells were transfected with carrier RNA or NV RNA and incubated for 8, 24, 48, and 72 h. At each time point, cells were either lysed for IP and Western blotting of VP1 (D) or extracted for cellular RNA to quantify NV RNA by RT-qPCR (E). WB, Western blotting.