(A)-(C) Secondary structure of the complete sfRNAs of DENV2 (A), ZIKV (B) and WNV (C). The stem-loop structures (SLI and SLII), SL3 of WNV, pseudo-dumbbell (ψ-DB1) structure of ZIKV, duplicated dumbbell structures (DB1, DB2), as well as the essential 3' SL are indicated. Sequences involved in pseudoknots (PK1, PK2, PK3, PK4) formation are indicated with red lines. 