False-colour transmission electron micrograph (TEM) of Human T-Cell Leukaemia Virus I (HTLV-1, red spheres). HTLV-1 is the cause of a virulent form of leukaemia found in Japan, the Caribbean and Africa. The virus is a member of the retrovirus family which includes HTLV-3 (now called HIV), the cause of AIDS. HTLV-1 acts by infecting T-lymphocyte cells and taking over the genetic machinery so as to reproduce itself. The virus is spherical and about 100-120 nanometres in diameter. Magnification x6300 at 6x7cm size.