It is now known that a large number of hepatitis cases are due to an RNA virus termed hepatitis C virus. Its existence and role in the etiology of hepatitis was identified by prepar-ing numerous complementary DNA clones from the presumed RNA virus in infectious serum. Peptides encoded by these clones were then tested for reaction with sera from cases of hepatitis and one was found to be highly specific, providing a basis for a serologic test.
Hepatitis C virus is an RNA virus in the flavivirus (eg, yellow fever, dengue) family. It has a very simple genome, consisting of just three structural and five nonstructural genes. There are at least six major genotypes, with multiple subtypes. The genotypes have differ-ent geographic distributions and may be associated with differing severity of disease as well as response to therapy.