HIV virus. Coloured transmission electron micrograph of HIV viruses budding from the surface of a host T-lymphocyte white blood cell (bottom). The viruses are here acquiring their viral membrane (green) from the host cell plasma membrane as they depart. Human Immunodeficiency Virus, or HIV, is responsible for AIDS. The T- lymphocyte cell is involved in the body's immune response. HIV viruses infect T-cells by injecting viral genetic material into the cell, causing it to form new HIV viruses. These new viruses bud out of the cell, damaging the cell membrane. The T- cell may thus die, weakening the body's immune system. Magnification: x72,000 at 6x4.5cm size.