GB virus C infection in patients with type II mixed cryoglobulinemia

Background: Hepatitis C virus (HCV) infection is present in most but not all patients with type II mixed cryoglobulinemia. Objective: To investigate the role of GB virus C (GBV-C) in type II mixed cryoglobulinemia. Design: Retrospective study of serum and cryoprecipitate samples. Setting: Tertiary care hospital in Bergamo, Italy. Patients: 58 cryoglobulinemic patients, 35 of whom were treated with interferon-alpha. Measurements: GB virus C RNA was determined by a reverse-transcription polymerase chain reaction assay done by using primers derived from the conserved GBV-C helicase region. Results: GB virus C RNA was detected in serum specimens from 23 of 58 cryoglobulinemic patients (40% [95% CI, 27% to 53%]) and 1 of 145 healthy blood donors (0.7%) (P < 0.001). Twenty of the 23 patients with GBV-C RNA were simultaneously infected with HCV. Unlike antibodies to HCV and HCV RNA, GBV-C RNA did not concentrate in cryoprecipitate in patients co-infected with GBV-C and HCV. Furthermore, the therapeutic effectiveness of interferon-alpha in patients with coinfection was related to the disappearance of HCV RNA but not GBV-C RNA from serum. None of 3 patients with GBV-C infection alone had detectable GBV-C RNA in cryoprecipitate. Conclusions: Infection with GBV-C, usually associated with HCV, is common in patients with type II mixed cryoglobulinemia but is unlikely to have a primary role in this disease.