False-colour transmission electron micrograph of Human Herpes Virus type 6 (HHV6) on the surface of an infected human cell. At the cell membrane surface, round virus particles are seen each with a thick protein envelope and a darker staining core of DNA genetic material. Cell cytoplasm (blue and yellow) is granular containing cell contents. These HHV6 viruses have left the infected cell, and will reinfect other cells. These viruses were isolated from an AIDS patient suffering secondary infection; HHV6 is now known to be the cause of the childhood disease roseola infantum which produces sudden fever, irritability and a skin rash. Magnification: x25,200 at 6x4.5cm size.