FIG. 5.

Mutagenesis of the 3′ end of the BVDV DI9c 3′ UTR. A schematic drawing of the diverse mutations which were introduced into the 3′ UTR of DI9c RNA is shown. The 3′ terminus of the RNA is depicted in its secondary structure suggested in Fig. 4; the numbering scheme is the same as in the previous figures. The substitutions are indicated by arrows, and the resulting DI9c RNA mutants are denoted with numbers 1 to 15.