Herpes virus. Transmission electron micrograph (TEM) of human herpes virus type 6 (HHV-6) infecting a human cell. The round virus particles each have a protein envelope (orange) and a core of DNA (deoxyribonucleic acid, pink). Once mature, the viruses will emerge from the cytoplasm and burst out of the cell to infect other cells. These viruses were isolated from an AIDS patient with HHV-6 as a secondary infection. HHV-6 is now known to be the cause of the childhood disease roseola infantum which produces sudden fever, irritability, and a skin rash. Magnification: x14,000 at 6x7cm size.