LOW-LEVEL OR ABSENT IN-VIVO REPLICATION OF HEPATITIS-C VIRUS AND HEPATITIS-G VIRUS GB-VIRUS-C IN PERIPHERAL-BLOOD MONONUCLEAR-CELLS

To investigate which subsets of peripheral blood mononuclear cells (PB MCs) are susceptible to infection with hepatitis C virus (HCV) and hep atitis G virus (HGV) or GB virus C (GBV-C), a PCR-based assay using ta gged primers in the core region (HCV) and NS3 region (HGV/GBV-C) for t he specific detection of negative strand (replicating) viral RNA seque nces was developed, In liver biopsy samples both positive and negative strands of HCV RNA were detected, at levels ranging from 3 to 11 x 10 (6) RNA copies per 10(6) cells and 3.7-4.2x10(3) copies per 10(6) cell s respectively, while lower frequencies of positive strands of GBV-C/H GV RNA were detected (from 13 biopsies, the highest frequency was 7.3 x 10(3) per 10(6) cells), In no samples were negative RNA strands dete cted, To investigate extra-hepatic replication of HCV and GBV-C/HGV, C D4(+), CD8(+) and B lymphocytes, monocytes and putative dendritic cell populations were separated from PBMCs from ten study subjects, Detect ion of positive strand HCV RNA was largely confined to B lymphocytes ( at levels of up to 5 x 10(3) copies per 10(6) cells), while detection of negative strands was confined to a single subset (dendritic cells) of one of the study individuals. Similarly, GBV-C/HGV was detected at low levels in only twelve of twenty PBMC samples, while negative stran ds were uniformly absent, The low levels of HCV and GBV-C/HGV RNA in P BMCs suggest that these cells are at most a minor reservoir for virus replication, The absence of detectable replication of GBV-C/HGV sugges ts that the actual site of GBV-C/HGV replication remains to be discove red.