False-colour transmission electron micrograph (TEM) of two particles of HIV-2, a virus causing AIDS. The viral protein coat (orange) has small surface projections; inside, a cone-shaped nucleoid (red) contains genetic material in the form of RNA. HIV-2 (Human Immunodeficiency Virus type 2) is more closely related to the Simian Immunodeficiency Virus (SIV) of monkeys, than is HIV-1. However, both types attack T-lymphocytes (white blood cells) of the human immune system, undermining the body's defences & exposing those infected to a range of opportunistic infections. Magnification: x26,200 at 6x7cm size.