FIG. 2.

Intergenotypic JFH1-based recombinant HCV with Core-NS2 of genotypes 1a, 1b, 2b, 3a, and 4a were infection impaired upon HVR1 deletion, but the infectivity of most viruses could be rescued by envelope mutations. The spread of viruses (genotypes 1a, 1b, 2b, 3a, and 4a) following HCV RNA transfection of Huh7.5 cells was moni- tored by determining the percentage of infected cells by HCV-specific immunostaining and HCV supernatant infectivity titers by FFU assay, shown as the mean of three replicates with SD (the lower cutoff was 100 FFUs/ml). The original virus is shown by black squares, HVR1-deleted virus is shown by purple triangles pointing up, and HVR1-deleted virus with one or more HVR1 deletion adaptive envelope mutations is shown by green triangles pointing down or by orange diamonds. All mutations are annotated based on the H77 reference sequence (GenBank accession no. AF009606). n.d., not detected.