FIG. 1.

Schematic of the HCV subgenomic replicon. Translation of the neomycin resistance sequence (neomycin) is initiated at the HCV IRES, whereas expression of the polyprotein containing the HCV nonstructural proteins 3 (protease and helicase), 4A, 4B, 5A, and 5B (RNA-dependent RNA polymerase) is initiated at the EMCV IRES. An amino-terminal 17-amino-acid portion of the HCV core coding sequence (HCV core) is included immediately downstream of the HCV IRES. Processing of the viral polyprotein by the viral proteinase results in formation of the membrane-associated HCV replication complex. The complex mediates transcription of the replicon RNA from the authentic HCV 3′ and 5′ untranslated regions (bold lines) (19).