Herpes virus particles. Transmission electron micrograph (TEM) of a cluster of Herpes simplex 1 (HSV-1) virus particles (round) in infected tissue. Each particle consists of a deoxyribonucleic acid (DNA) core (dark purple) surrounded by an icosahedral (20-sided) outer coat (capsid), which is itself surrounded by an envelope. Herpes simplex causes oral herpes (cold sores) and genital herpes in humans. There is no known cure for it and the virus remains in the body for life.