Biophysical characterization of GB virus C from human plasma.

Viral characterization studies were carried out on GB virus C (GBV-C) RNA positive plasma from normal human donors and from donors co-infected with GBV-C and hepatitis C virus (HCV). GBV-C RNA was detected by reverse-transcriptase polymerase chain reaction (RT-PCR) and probe hybridization in a single tube assay. Sequential filtration of GBV-C positive plasma indicated that GBV-C RNA is associated with a particle 50-100 nm in diameter. The peak of GBV-C RNA in sucrose gradients was observed at a buoyant density of 1.05-1.13 g/ml. GBV-C RNA titer was reduced following treatment with chloroform or with five detergents indicating that GBV-C has a lipid-containing envelope. Sucrose density gradients and self-forming cesium chloride gradients of detergent-treated GBV-C showed a shift in the RNA peak to heavier buoyant density only when RNase inhibitor (RNasin) and high detergent concentrations were present. The treated material was non-filterable and the RNA had a density of > 1.5 gm/ml.