Of lives and livers: emerging responses to the hepatitis C virus.

Hepatitis C is an infectious disease affecting the liver, caused by the hepatitis C virus (HCV). HCV is an etiological agent of acute and chronic liver disease that exists throughout the world. The high genetic variability of the HCV genome is reflected by six genotypes (1 to 6). Each genotype has a characteristic geographical distribution, which is important epidemiologically. HCV is a blood-borne virus that generally circulates in low titers in the serum of infected individuals. Epidemiologic studies show that the most efficient transmission of HCV is through the transfusion of blood or blood products, the transplantation of organs from infected donors, and the sharing of contaminated needles among injection-drug users. However, fewer than half of patients with acute hepatitis C report a history of such exposure. A small number of epidemiologic studies demonstrate that perinatal, sexual, household, and occupational transmission occurs, but our understanding of the risks of transmission in these settings has been limited. The therapy for chronic hepatitis C has evolved steadily since alpha interferon was first approved for use. At present, the optimal regimen appears to be a 24- or 48-week course of a combined pegylated alpha interferon and ribavirin regimen. Currently, the combination of RNAi (LV-shIRES) with IFN-α has been proposed to prevent therapeutic resistance, and to promote enhanced antiviral activity against HCV. However, any RNAi based therapy may be years away due to off-target effects.