C3P3-G1: first generation of a eukaryotic artificial cytoplasmic expression system

Jaïs, Philippe H; Decroly, Etienne; Jacquet, Eric; Le Boulch, Marine; Jaïs, Aurélien; Jean-Jean, Olivier; Eaton, Heather; Ponien, Prishila; Verdier, Fréderique; Canard, Bruno; Goncalves, Sergio; Chiron, Stéphane; Le Gall, Maude; Mayeux, Patrick; Shmulevitz, Maya

The lack of 5 -RNA cap on T7-transcripts likely contributes to their poor translational efficiency (24, 27) . In support of this hypothesis, the vaccinia virus-T7RNAP (VV-T7RNAP) expression system was found superior to T7RNAP expression alone (28, 29) . This elegant expression system relies on infection of mammalian cells by a recombinant vaccinia virus encoding T7RNAP, which transcribes target genes under control of the T7-promoter embedded in a second recombinant vaccinia virus or plasmid. The transcripts produced by this system can receive 5'-cap and 3'-polyadenylation by the vaccinia virus capping and polyadenylation machineries, respectively (30) . Although this expression system is able to generate up to 30% of the total cytoplasmic RNA, only 5-10% of the T7-transcripts are capped and 25% of them are polyadenylated, which suggests insufficient synergy between the transcriptional and post-transcriptional machineries (30, 31) .