Characterization of the HCV core virus-like particles produced in the methylotrophic yeast Pichia pastoris

Little is known about the mechanism of hepatitis C virion assembly. So the capacity of the entire Hepatitis C virus core protein (HCcAg) produced in P ichia pastoris to form particles either in its native soluble state or afte r detergent treatment of HCcAg associated to cell debris were studied. Size exclusion chromatography suggested that HCcAg assembled into high molecula r weight structures. HCcAg was also specifically recognized by a serum from a chronic HCV carrier patient. This antigen migrated with buoyant density values similar to those obtained for native nucleocapsid particles from inf ected patients when analyzed using sucrose density gradient centrifugation. The analysis by electron microscopy of purified HCcAg showed aggregates re sembling virus-like particles (VLPs) with an average diameter of 30 nm. The se results indicated that the HCcAg obtained from P. pastoris assembled int o VLPs resembling HCV nucleocapsid particles in a mature stage. Such HCcAg aggregates characterized here could be a valuable tool to elucidate the mec hanisms of HCV nucleocapsid assembly. (C) 2001 Academic Press.