Hepatitis B virus. Coloured transmission electron micrograph (TEM) of the Hepatitis B virus and its naturally occurring antigen. The green spheres (called Dane particles) are the complete virus. Hepatitis B virus occurs typically in clusters of three types of particles (as seen here): the virus itself, with smaller spheres and rod-shaped forms made from the protein coat of the virus. The smaller non-infectious spheres (blue) are anti- genically identical to the virus, and provide raw material for Hepatitis B vaccines. Infection by this virus is more serious than Hepatitis A, can be sexually transmitted, and causes chronic hepatitis. Magnification: x110,000 at 5x7cm size. Magnification; x55,000 at 35mm size.