Detection of hepatitis C virus in paraffin‐embedded liver biopsies of patients negative for viral RNA in serum

The diagnosis of hepatitis C is based on serological testing for antibodies against various epitopes of the hepatitis C virus (HCV) and detection of HCV RNA in serum, because anti‐HCV antibodies alone cannot discriminate patients who are infectious from those who have resolved the infection. If HCV RNA is not detected, which is the case in at least 20% of enzyme immunoassay (EIA)‐positive patients, diagnosis remains unclear in a state of disease possibly well suited for therapeutic intervention. Therefore, we investigated if detection of HCV antigens or HCV RNA in routinely processed, formalin‐fixed and paraffin‐embedded (ffpe) liver biopsy specimens of patients positive for anti‐HCV, but negative for HCV RNA in serum, could confirm diagnosis in this serological constellation. We detected HCV RNA by reverse‐transcription polymerase chain reaction (RT‐PCR) in 27 (61%) of 44 ffpe liver biopsies from EIA‐positive, but HCV‐RNA–seronegative, patients. Testing of 18 of these biopsies by a panel of polyclonal antibodies against structural and nonstructural HCV proteins revealed positive immunostaining in 6 cases (33%), which were also positive by RT‐PCR. Most biopsies showed necroinflammation compatible with chronic hepatitis C, and the detection of tissue HCV RNA correlated significantly with a higher grade of inflammatory activity. Detectability of HCV RNA did not correlate with HCV subtype. In conclusion, the search for HCV RNA by RT‐PCR within the liver biopsy specimen can establish rapid and unequivocal diagnosis of hepatitis C in at least 60% of anti‐HCV antibody–positive patients who are seronegative for HCV RNA, and thus may help to avoid repeated testing and delayed therapy. Tissue RT‐PCR may also be more efficient than serological testing for surveillance of interferon therapy response, because ongoing chronic active hepatitis C is clearly demonstrated in the absence of detectable serum HCV RNA.