Coloured transmission electron micrograph of Human Herpes Virus type 6 (HHV6) infecting a human cell. Within a pseudopodium (cell outgrowth centre), virus particles (red) are seen each with a thick protein envelope and a darker staining core of DNA genetic material. Some particles have an immature coat and core. Once mature, these HHV6 viruses will leave the cell to reinfect other human 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: x29,900 at 6x4.5cm size.