The cloning and sequencing of the hepatitis C virus (HCV) genome represented a major breakthrough in modern virology ‘: this was the first virus identification based almost entirely upon characterization of the ge-nomic sequence. In fact, HCV was not visualized by electron microscopy until only recently. 2 The invention of the polymerase chain reaction (PCR) was essential for most of the molecular studies of HCV because the level of viremia in infected individuals is usually too low to be detected by other means. 3’4 After the development of specific serological tests for antibody to HCV (anti-HCV) S it was demonstrated that most cases of transfusion-associated non-A, non-B hepatitis, as well as community-acquired non-A, non-B hepatitis, were associated with HCV infection.‘/” 7 The detection of genomic HCV sequences with sensitive and specific cDNA PCR as-says?" 11 confirmed that HCV viremia correlated with progression to chronic hepatitis in non-A, non-B hepatitis patients.“_'3 Thus, it was established that HCV is a major etiologic agent of acute and chronic hepatitis around the world. 6 An astonishingly high proportion of individuals acutely infected with HCV become chronically infected (approximately 80%), and more than 20% of these individuals will eventually develop liver cirrho-sis. 6 Interestingly, a strong association has been found between HCV infection and the development of hepato-cellular carcinoma.“" 5 Finally, HCV infection seems to be associated with other diseases, including some au-toimmune diseases “‘'17 and type II cryoglobulinemia. 18