Figure 1.

vtRNAs are significantly upregulated during IAV infection both in vitro and in vivo. (A) The differentially expressed ncRNAs in A549 cells infected with or without A/WSN/33 influenza virus were analyzed by a cDNA microarray (http://www.ncbi.nlm.nih.gov/geo/; GEO access number GSE58741). Shown are representative ncRNAs whose expressions were significantly changed. vtRNAs are indicated by red rectangle. (B, C) A549 cells were infected with or without WSN for 16 h. RT-PCR (B) and qRT-PCR (C) were performed to determine the expression of vtRNAs. (D) A549 cells were infected with WSN at indicated MOIs for 16 h. Northern blotting was performed to determine vtRNAs expression. 5S rRNA was used as a loading control. (E) The expression of vtRNAs in indicated human cell lines infected with or without WSN for 16 h was examined by RT-PCR. The viral nucleoprotein (NP) was examined by western blotting. (F) The mvtRNA expression in mouse cell lines infected with or without WSN for 18 h was examined by RT-PCR. The viral nucleoprotein (NP) was examined by Western blotting. (G) C57BL/6 mice intranasally infected with or without WSN (5 × 10⁴ PFU) for 2 days were sacrificed, and the lungs were dissected and lysed, followed by qRT-PCR to examine the mvtRNA levels. Shown are representative results from three independent experiments. The error bars represent the SE, **P < 0.01.