Adenoviruses. Coloured transmission electron micrograph (TEM) of three adenovirus particles. There are many kinds of adenoviruses that are all icosahedral (20-sided) viruses. They infect the respiratory tract, causing common cold-like symptoms, and also infect the eyes and gut, particularly in children. The ball-and-stick objects on the surface (orange) are fibres that are detaching from the particles. Virus particles consist of a protein coat that contains genetic material. They replicate by invading cells, inserting their own genes and causing the cell to produce more virus particles. Magnification: x103,000 at 6x7cm size.