False-colour transmission electron micrograph (TEM) of 3 virions (virus particles) of the mumps virus (a member of the paramyxoviridae virus family). Individual virions possess a protein capsid (surrounding genetic information in form of RNA) which has helical symmetry (the particles themselves are roughly spherical). Surrounding the capsid is a protein envelope covered in projections made up of sub-units of haemagglutinin (permits agglutination of red blood cells) & enzyme neuraminidase. Symptoms of mumps include fever, headache & vomiting, preceding swelling of the parotid salivary glands in neck. Magnification: X 76,500 at 35mm size.