Herpes simplex virus particles, coloured transmission electron micrograph (TEM). Each particle consists of deoxyribonucleic acid (DNA) genetic material surrounded by an icosahedral (20-sided) outer coat (capsid, orange), which is itself surrounded by an envelope covered in glycoprotein spikes (not seen). The herpes simplex virus (HSV) causes watery blisters on the skin, mucous membranes and genitals. HSV is divided into two types: HSV1 (oral herpes) and HSV2 (genital herpes). Other viruses in the herpes family that infect humans include varicella-zoster virus (chicken pox and shingles), Epstein-Barr virus (glandular fever) and cytomegalovirus. Magnification: x125,000 when printed 10 centimetres tall.