Genetic diversity and evolution of hepatitis C virus - 15 years on

• Published in: Journal of general virology Vol. 85; no. 11; pp. 3173 - 3188
• Main Author: Simmonds, Peter
• Format: Journal Article
• Language: English
• Published: Reading Soc General Microbiol 01.11.2004; Society for General Microbiology
• Subjects: Biological and medical sciences; Biological Evolution; Disease Transmission, Infectious; Fundamental and applied biological sciences. Psychology; Genetic Variation; Genetics; Genome, Viral; Genotype; Hepacivirus - classification; Hepacivirus - genetics; Hepacivirus - pathogenicity; Hepatitis C - transmission; Hepatitis C - virology; Hepatitis C virus; Human viral diseases; Humans; Infectious diseases; Liver - virology; Medical sciences; Microbiology; Miscellaneous; RNA, Viral - genetics; Viral diseases; Viral Envelope Proteins - genetics; Viral hepatitis; Viral Nonstructural Proteins - genetics; Virology; Microbiology; Hepatic disease; Genetic diversity; Virology; Infection; Virus; Viral disease; Digestive diseases; Evolution; Genetics; Flaviviridae; Hepatitis C virus; Hepacivirus; Viral hepatitis C
• ISSN: 0022-1317; 1465-2099
• DOI: 10.1099/vir.0.80401-0

Centre for Infectious Diseases, University of Edinburgh, Summerhall, Edinburgh EH9 1QH, UK Correspondence Peter Simmonds Peter.Simmonds{at}ed.ac.uk In the 15 years since the discovery of hepatitis C virus (HCV), much has been learned about its role as a major causative agent of human liver disease and its ability to persist in the face of host-cell defences and the immune system. This review describes what is known about the diversity of HCV, the current classification of HCV genotypes within the family Flaviviridae and how this genetic diversity contributes to its pathogenesis. On one hand, diversification of HCV has been constrained by its intimate adaptation to its host. Despite the >30 % nucleotide sequence divergence between genotypes, HCV variants nevertheless remain remarkably similar in their transmission dynamics, persistence and disease development. Nowhere is this more evident than in the evolutionary conservation of numerous evasion methods to counteract the cell's innate antiviral defence pathways; this series of highly complex virus–host interactions may represent key components in establishing its ‘ecological niche’ in the human liver. On the other hand, the mutability and large population size of HCV enables it to respond very rapidly to new selection pressures, manifested by immune-driven changes in T- and B-cell epitopes that are encountered on transmission between individuals with different antigen-recognition repertoires. If human immunodeficiency virus type 1 is a precedent, future therapies that target virus protease or polymerase enzymes may also select very rapidly for antiviral-resistant mutants. These contrasting aspects of conservatism and adaptability provide a fascinating paradigm in which to explore the complex selection pressures that underlie the evolution of HCV and other persistent viruses. Published online ahead of print on 19 August 2004 as DOI 10.1099/vir.0.80401-0.