Direct evidence that the poly(A) tail of influenza A virus mRNA is synthesized by reiterative copying of a U track in the virion RNA template.
Poon LL., Pritlove DC., Fodor E., Brownlee GG.
The poly(A) tail of influenza virus mRNA is thought to be synthesized by reiterative copying of the U track near the 5' end of the virion RNA template. This has been widely accepted as a plausible hypothesis, but until now there has been no direct experimental evidence for it. Here, we report such direct evidence based on the fact that (i) replacing the U track with an A track directs synthesis of products with poly(U) tails, both in vitro and in vivo, and (ii) interrupting the U track abolishes polyadenylation in vitro.