Hepatitis C virus

Abstract

Hepatitis C virus (HCV) is a small, enveloped, 9.6 kb positive strand RNA virus that belongs to the genus Hepacivirus within the Flaviviridae family. Hepatitis related to HCV is a progressive disease that may result in chronic active hepatitis, cirrhosis and hepatocellular carcinoma. Since it is estimated that about 200 million individuals are chronically infected with HCV and there is no available vaccine, the virus represents serious global health problem. Although direct-acting antiviral agents were recently approved and made available and that more drugs are in the pipeline, patients response to the current standards of care therapy (pegylated interferon?α and ribavirin) is limited. Given this fact, and since the liver is the major site of HCV replication, liver failure arising because of HCV infection is one of the most common reasons for the organ transplant. Its high replicative activity, together with the lack of proof-reading activity of the viral RNA dependent RNA polymerase, are the basis of the high genetic variability of HCV, as well as of the high degree of intra-host genetic diversity. HCV isolates are classified into seven major genetic groups referred to as genotypes, which present distinct geographical distribution. Moreover, HCV exists as an ensemble of closely related but genetically divergent variants, commonly referred to as ?quasispecies?. The mechanisms leading to liver injury are under constant revision, but the fact that both immune system-mediated reactions and viral cytopathic effects are involved in pathogenesis is widely accepted. In this chapter, we addressed HCV structure, cell cycle, pathogenesis, classification and genetic variability in order to understand the clinical manifestations of HCV infection and the treatment strategies.