Three oligonucleotide primer combinations selected from the 5' noncoding, the nucleocapsid and the putative nonstructural regions of the hepatitis C virus genome were compared in a nested polymerase chain reaction assay with respect to sensitivity and specificity for the detection of viral RNA in chimpanzeeinfected and human-infected sera. Sera from both the acute and the chronic phase of the infection were obtained from 13 animals inoculated with five different non-A, non-B hepatitis strains and from seven cardiac surgery patients who had non-A, non-B hepatitis develop after transfusion and who had been tested in parallel for the presence of hepatitis C virus RNA and anti-C100-3. A total of 90% of the acute-phase and 100% of the chronic-phase sera tested positive for hepatitis C virus RNA when the 5' noncoding4erived or the nucleocapsid-derived combinations were used; only 58% and 56%, respectively, gave positive results with the putative nonstructural primers, whereas 33% and 71%, respectively, scored positive for C100-3. Thus polymerase chain reaction primers selected from either the highly conserved 5' noncoding or nucleocapsid-regions appear to provide the sensitivity and the specificity necessary to detect low levels of hepatitis C virus RNA in both chimpanzee-infected and human-infected sera. (HEPATOLOGY 199 1; 14595-600. ) The virus of non-A, non-l3 (NANB) hepatitis is responsible for more than 90% of the cases of hepatitis after transfusion (1-4). An estimated 3 5 9 to 50% of NANB-diagnosed patients will have chronic liver disease develop (5-6).
The partial cloning of a small positive-stranded RNA virus provided preliminary characterization of the NANB agent now named hepatitis C virus (HCV) (7). This cloning led to the development of a serological test for the detection of antibodies using a recombinant nonstructural polypeptide ((2100-3) coded for by the genome of HCV (8). The C100-3 immunoassay has been