VIRION-LIKE STRUCTURES IN HELA G CELLS TRANSFECTED WITH THE FULL-LENGTH SEQUENCE OF THE HEPATITIS-C VIRUS GENOME

Background & Aims: The process and the site of hepatitis C virus (HCV) particle formation in cells after infection remain unknown. The aim o f this study was to create an in vitro model for the study of HCV part icle formation. Methods: HeLa G cells were transfected with the full-l ength sequence of the HCV genome. Viral protein expression was analyze d using immunoblotting. The cells were examined using immunoelectron a nd conventional electron microscopy. Results: Core, E2, NS3, NS5a, and NS5b proteins were identified using immunoblotting. Immunoelectron mi croscopy showed that the core antigen was located along the membrane o f the endoplasmic reticulum (ER) and occasionally in its cisternae. Co re antigen- positive particles of 30 nm in diameter were found in the cytosol and in the cisternae of the ER. The particles in the cisternae were coated with an outer membrane that was connected to the ER membr ane. Conventional electron microscopy revealed particles of 45 nm in d iameter with electron-dense cores in the cisternae of the ER. The oute r membrane of thef particles was occasionally connected to the ER memb rane. Conclusions: The findings suggest that HCV core proteins are syn thesized and assembled into particles in the cytosol and that they bud into the cisternae of the ER to form coated particles.