FIG. 1.

Proposed secondary and tertiary RNA structures within the 5′NTR and the immediately downstream segment of the long open reading frame of the genotype 1b virus HCV-N (10, 11). Major structural domains are labeled I, II, IIIa, IIIb, etc.; the initiator AUG codon in stem-loop IV is highlighted. The circled nucleotides indicate differences between the sequences of HCV-N and the genotype 1a HCV-H virus, which are clustered at four loci: UGA, GA, A₁, and A₂.