Dynamics of GB virus C viremia early after orthotopic liver transplantation indicates extrahepatic tissues as the predominant site of GB virus C replication.

The principal site of GB virus C (GBV-C) replication is unknown. To determine whether hepatic GBV-C replication is important for the maintenance of a measurable viremia level in GBV-C infection, the influence of hepatectomy followed by liver transplantation on GBV-C viremia was investigated. GBV-C RNA levels were determined by a quantitative TaqMan polymerase chain reaction (PCR) in 12 patients with pretransplantation GBV-C infection before and daily after orthotopic liver transplantation (OLT) for 25 to 28 days. Compared with the pretransplantation values (mean, 12.4 +/- 3.9 x 10(7) copies/mL), mean GBV-C RNA levels declined significantly by 1 log by day 1 after OLT (mean, 3.5 +/- 1.6 x 10(7) copies/mL), but subsequently remained relatively stable on this high level for the entire observation period, indicating ongoing high-level virus replication (mean GBV-C RNA levels on days 7 and 28 were: 1.7 +/- 0. 5 x 10(7) and 2.8 +/- 0.7 x 10(7) copies/mL; P = ns). Thus, at the end of the follow-up, mean GBV-C RNA levels were not significantly different from that of the 1st and 7th postoperative day and remained significantly lower compared with the pretransplantation values. However, in 2 of the 12 patients, different kinetics were observed. Both already had low-level viremia pre-OLT (0.02 and 0.002 x 10(7) copies/mL) and became persistently GBV-C RNA-negative 2 days after OLT. In 5 patients, liver tissues were collected 6 to 9 days after OLT and investigated for GBV-C RNA. All but 1 were GBV-C RNA-negative in the liver, although 2 of them had rather high serum GBV-C RNA levels at this time. The kinetics of GBV-C viremia observed in our study were neither influenced by the immunosuppressive therapy nor by the number of blood and blood product transfusions given after OLT. In addition, they were quite different from those observed in patients with chronic hepatitis C in whom early reinfection of the graft could be demonstrated by a steady increase in HCV RNA levels starting 3 days after OLT and exceeding preoperative levels by day 8. From our data, one can conclude that the liver is certainly not the major site of GBV-C replication in most patients. However, one cannot exclude that host or viral factors exist that predispose GBV-C replication predominantly in the liver.