Rescue of the 1947 Zika Virus Prototype Strain with a Cytomegalovirus Promoter-Driven cDNA Clone

Schwarz, Megan C.; Sourisseau, Marion; Espino, Michael M.; Gray, Essanna S.; Chambers, Matthew T.; Tortorella, Domenico; Evans, Matthew J.

Indeed, sequence analysis of bacterial plasmid clones of these RT-PCRs demonstrated that all products from wild-type plasmid-transfected cell RNA lacked the inserted intron (Fig. 3B) . In contrast to parental virus RT-PCR products (Fig. 3B) , these sequences carried a single silent G3127A mutation that was inserted during intron cloning, which indicated that these RNAs were generated from the MR766 plasmid. While spliced sequences were observed in eight of the 15 bacterial plasmid clones of the Pol(Ϫ) RT-PCR products, seven of these clones retained the intron sequence (Fig. 3B) . These results confirmed that splicing can remove the intron from RNA transcribed from both the wild-type and Pol(Ϫ) MR766 plasmids. Furthermore, the greater abundance of spliced RNA in wild-type plasmid-transfected cells may represent amplification due to viral RNA replication.