Analysis of hepatitis C virus/classical swine fever virus chimeric 5'NTRs: sequences within the hepatitis C virus IRES are required for viral RNA replication

• Published in: Journal of general virology Vol. 84; no. 7; pp. 1761 - 1769
• Main Authors: Reusken, Chantal B. E. M, Dalebout, Tim J, Eerligh, Peter, Bredenbeek, Peter J, Spaan, Willy J. M
• Format: Journal Article
• Language: English
• Published: England Soc General Microbiol 01-07-2003
• Subjects: 5' Untranslated Regions - genetics; Base Sequence; Classical swine fever virus; Classical Swine Fever Virus - genetics; Hepacivirus - genetics; Hepatitis C virus; Humans; Molecular Sequence Data; Nucleic Acid Conformation; Protein Biosynthesis; Recombination, Genetic; Regulatory Sequences, Ribonucleic Acid - genetics; Ribosomes - chemistry; Ribosomes - metabolism; RNA, Viral - biosynthesis; RNA, Viral - genetics; Tumor Cells, Cultured; Virus Replication
• ISSN: 0022-1317; 1465-2099
• DOI: 10.1099/vir.0.19063-0

Molecular Virology Laboratory, Department of Medical Microbiology, Center of Infectious Diseases, Leiden University Medical Center, LUMC E4-P, PO Box 9600, 2300 RC Leiden, The Netherlands
Correspondence Willy Spaan W.J.M.Spaan{at}LUMC.NL
Hepatitis C virus (HCV) is classified in the genus Hepacivirus of the family Flaviviridae , whose members have a single-stranded RNA genome of positive polarity, which encodes a single polyprotein. Within this family, HCV is closely related to viruses of the genus Pestivirus , which includes classical swine fever virus (CSFV). Translation of the hepaci- and pestiviral polyprotein is initiated by internal entry of ribosomes, promoted by the 5'NTR. The secondary and tertiary RNA structures of the HCV and pestivirus 5'NTRs are well conserved, despite the fact that their sequences differ significantly from one another. By analogy with other positive-stranded RNA viruses, the 5'NTR of HCV is likely to contain cis -acting determinants for replication as well as the determinants for translation. Studies on both signals could be complicated, as these signals might overlap. In this study, this problem was addressed by constructing chimeric HCV/CSFV 5'NTRs. A two-step analysis of these 5'NTRs was performed: (a) in a translation assay, which provided the possibility to study translation independently of the possible effects on replication; and (b) in a replication assay, in which were studied only the chimeric 5'NTRs for which IRES-dependent translation was demonstrated. An overlap was observed between HCV RNA elements involved in these processes. Exchange of domain II had a minor effect on the translation efficiency of the chimeric 5'NTRs, while replication of subgenomic replicons with these chimeric 5'NTRs was abolished. Exchange of domain III subdomains severely decreased translation activity, while replication was maintained.