Figure 2

Anatomy of trans -splicing group I introns. The IGS forms the P1 helix with the target to bring it into proximity with the GNP 3'-OH. The EGS is an extra stretch of antisense RNA that improves the efficiency and specificity of intron targeting the desired viral sequence. The formation of the P10 helix brings the newly cleaved 3'-OH of the uracil into proximity with the 3' exon, allowing covalent splicing. P1 and P10 overlap by 2 bp IGS upon targeting of the DENV-2 genome. A UAA stop codon was inserted in the trans-splicing domain of each intron immediately upstream of the UCG splice site to prevent inadvertent translation of the 3' exon until formation of the DENV 2-FL spliced product. The sites of trans-esterification on the phosphodiester backbone (1 and 2) are marked with black arrows.