Role of 3'-end sequences in infectivity of poliovirus transcripts made in vitro.

TLDR: T7D-polio, a plasmid that allows the in vitro synthesis of full-length RNA molecules with two additional guanine residues at the 5' end, differed from the construct of van der Werf et al. in that RNA transcribed from T7D -polio has an authentic 3'end, ending with only a polyadenine nucleotide sequence.

Abstract: It has been shown by van der Werf et al. (S. van der Werf, J. Bradley, E. Wimmer, F. W. Studier, and J. Dunn, Proc. Natl. Acad. Sci. USA 83:2330-2334, 1986) that in vitro synthesis of poliovirus RNA by T7 RNA polymerase gives rise to infectious RNA molecules; however, these molecules are only 5% as infectious as RNA isolated from virions. A plasmid, T7D-polio, was constructed that allows the in vitro synthesis of full-length RNA molecules with two additional guanine residues at the 5' end. However, T7D-polio differed from the construct of van der Werf et al. in that RNA transcribed from T7D-polio has an authentic 3' end, ending with only a polyadenine nucleotide sequence. Transfection of these RNA molecules into mammalian cells produced wild-type poliovirus with an efficiency similar to that of virion RNA. The use of this vector in the characterization of viral mutants in vivo and in vitro is discussed.