ULTRASTRUCTURAL OBSERVATIONS OF VIRAL PARTICLES WITHIN HEPATITIS-C VIRUS-INFECTED HUMAN B-LYMPHOBLASTOID CELL-LINE

Hepatitis C virus (HCV)-infected TOFE cells, a human bone marrow-deriv ed B-ceIl line, were studied by transmission electron microscopy (TEM) . We reported the presence of virus-like particles, (VLPs) having a di ameter of 45 nm on average, within the cytoplasm of HCV-infected cells and their absence in uninfected cells. The VLPs were mostly seen in d ilated cisternae of endoplasmic reticulum (ER) and consisted of an ele ction-dense core and a membrane envelope with surface projections. In the HCV-infected TOFE cells, examination by TEM revealed tubular struc tures similar to those observed in liver cells of chimpanzees and huma ns infected by the virus. In some instances, the outer membrane of the particles was connected io the ER membrane, indicating possible virus budding into the cisternae. Rarely, coated vesicles containing a part icle were seen. In most of the infected cells, enlarged cytoplasmic va cuoles filled with degenerative amorphous material were observed. The data suggest a flavivirus-like pattern of HCV morphogenesis in infecte d non-hepatic cells and identify lymphoblastoid TOFE cells as a valuab le system for the study of the sequential steps of the infection proce ss and the morphological effects produced by HCV infection.