FIG. 1.

(A) The proposed conformation and 93-nt sequence (12) of the DEN2 3′-SL. Nucleotides are numbered from the 3′ terminus of the DEN2 genome. For the purposes of this study, the DEN2 3′-SL was divided into top and bottom portions according to an approach taken for the 3′-SL of WN strain E101 (3). Segments of the DEN2 3′-SL that were mutagenized are indicated by brackets, labeled with the names of the respective mutant viruses. See Fig. 2 and 3 for the genotypes of mutant viruses. (B) The conformation and 96-nt sequence of the WN 3′-SL (4). Nucleotides are numbered beginning from the 3′ terminus of the genome. Top and bottom portions were previously defined (3). Segments of the WN 3′-SL nucleotide sequence that were substituted for the corresponding DEN2 nucleotide sequences in DEN2-WN chimeric RNAs are indicated by brackets labeled with the names of the resultant chimeric viruses (see Fig. 2).