Previous in silico studies have predicted a stable RNA structure designated SL6, in the C protein-encoding region, for a limited number of viruses within the mTBFV subgroup (16, (26) (27) (28) . Structural RNA elements were also revealed in the C region of some MBFV (28) although their homology to SL6 of TBFV had not been established. Here, we utilized a variety of independent structure prediction methods and a much larger sample of viral sequences to analyze whether or not the SL6-like structure was conserved throughout the entire genus Flavivirus.