In the minus-sense orientation, the conservation of an SL6-like structure was not as robust as in the positivesense. Although most of the TBFVs formed a structure in the minus-sense RNA, the number of hydrogen bonds, the lengths of the stems and free minimal energy of folding varied significantly even between closely related viruses (data not shown). Consequently, the formation of SL6 is likely to be biologically significant only in the positive-sense RNA.