FIG. 3.

Poly(U)-tailed NA mRNA is synthesized by the A₆ transfectant virus. (A) RT-PCR assays. Total RNA from cells infected with the wild-type virus (lanes 2, 5, and 8) or the A₆ mutant (lanes 3, 6, and 9) was tested by RT-PCR for vRNA (lanes 2 and 3), poly(U)-tailed NA mRNA (lanes 5 and 6), and poly(A)-tailed NA mRNA (lanes 8 and 9). RT-PCR products were analyzed on 8% native acrylamide gels. The high-molecular-weight bands near the wells are nonspecific PCR products. Lanes 1, 4, and 7 are DNA markers. (B) Poly(U) sequence n = 84) of a cDNA clone derived from poly(U)-tailed NA mRNA. The influenza virus mRNA sequence is indicated. N, either C, A, G, or T.