German measles virus. Computer artwork of a German measles (rubella) virus. At centre is the nucleocapsid core. The nucleocapsid consists of genetic material (RNA) and proteins and has icosahedral (20 sided) symmetry. Surrounding the nucleocapsid (orange and yellow) is the lipoprotein envelope. On the surface of the envelope are projections of haemagglutinin subunits (green). These enable the virus to stick to red blood cells. Rubella is spread in airborne droplets and occurs commonly in children as a mild rash. Rubella poses a more serious risk to unborn children if the mother is infected in pregnancy.