Background & aims: Infection of the lymphatic system by hepatitis C virus (HCV) appears to be an intrinsic characteristic of chronic hepatitis C (CHC) and low-level (occult) HCV infection, but the subsets of immune cells involved were not defined. The aim of this study was to characterize HCV replication status and to assess virus compartmentalization in CD4+ and CD8+ T lymphocytes, B cells, and monocytes in CHC, and silent infection persisting after resolution of hepatitis C.
Methods: Immune cell subtypes isolated from 7 patients with CHC and 7 individuals with occult infection were analyzed for HCV-RNA-positive and -negative strands and, in selected cases, nonstructural protein 5A display and HCV variants.
Results: All subtypes of immune cells investigated support HCV replication in both forms of infection, although significant differences were found between patients, and virus loads in the cells were greater in CHC than in occult infection. Although HCV RNA occurred at a comparable frequency in all cell subtypes in CHC, monocytes contained the greatest loads. In contrast, B cells tended to carry the highest virus quantities in occult infection, whereas monocytes appeared to be the least frequently infected. Detection of HCV nonstructural protein 5A and HCV variants that were not found in plasma confirmed virus replication in different immune cell types.
Conclusions: This work documents that the immune system supports HCV replication regardless of clinical appearance of infection and identifies immune cells that are reservoirs of HCV in symptomatic and occult infections.