Hepatitis C virus core particle detected by immunoelectron microscopy and optical rotation technique

Hepatitis C Virus (HCV) are 55-65 nm spherical particles, but the internal structure of the virion remains to be clarified. To clarify the morphology of HCV core particles, we performed an immune electron microscopy (IEM) usi ng plasma samples from two blood donors with high HCV RNA titers and a dete rgent-treated anti-HCV core antibody-free plasma sample with high HCV RNA t iter (1.5 x 10(8) copies/ml). Spherical particles, with 33-40 nm in diamete r tan average diameter of 37 nm) were found in 1.22-1.25 g/ml fractions aft er sucrose density gradient centrifugation by conventional electron microsc opy (EM). IEM using rabbit polyclonal antibody (RR8) specific to the putati ve HCV core protein and goat anti-rabbit IgG colloidal gold particles revea led that these spherical particles specifically reacted with RR8. This find ing indicates that the spherical particles are naked HCV core particles. So me of the HCV core particles had an icosahedron-like structure. Optical rot ation technique showed that the HCV core particle exhibits six-fold symmetr y and that the length of regular hexagon side is approximately 20 nm. These findings showed that HCV core particles are spherical particles of 33-40 n m in diameter and that HCV core particles may possess an icosahedron-like s tructure and a buoyant density of 1.22-1.25 g/ml. (C) 2001 Elsevier Science B.V. All rights reserved.