DETECTION AND LOCALIZATION BY IN-SITU MOLECULAR-BIOLOGY TECHNIQUES AND IMMUNOHISTOCHEMISTRY OF HEPATITIS-C VIRUS IN LIVERS OF CHRONICALLY INFECTED PATIENTS

Hepatitis C virus (HCV) detection in the livers of chronically infecte d patients remains a debatable issue. We used immunohistochemistry, in situ hybridization (iSH) alone or after microwave heating with FITC-l abeled probes, RT-PCR with unlabeled primers followed by ISH (RT-PCR-I SH), and in situ RT-PCR with FITC-labeled primers (in situ RT-PCRd) to localize the virus in 38 liver biopsy specimens from 21 chronically i nfected HCV patients treated with interferon-alpha (IFN-alpha). Biopsi es were taken at the beginning and end of IFN-alpha treatment and 1 ye ar later. Results were compared with that of HCV-PCR in serum. RT-PCR- ISH and in situ RT-PCRd showed HCV signal in all liver biopsies even i n responders with seronegative HCV PCR. This signal was intranuclear, diffuse, or peripheral, in hepatocytes, bile ductule cells, and lympho cytes. Cytoplasmic signals were occasionally observed. Whereas the per centage of labeled hepatocytes remained constant, the number of labele d lymphoid follicles decreased after INF-alpha therapy. Immunohistoche mistry resulted in the same pattern of positivity but it was weaker an d inconstant. This study indicates the persistency of HCV latency in I FN-alpha responders 1 year after IFN-alpha treatment cessation, a find ing that certainly deserves confirmation.