HIV virus. Coloured transmission electron micrograph of an HIV virus. HIV (Human Immuno- deficiency Virus) is the virus responsible for AIDS (Acquired Immunodeficiency Syndrome). This virus infects T-lymphocyte cells (white blood cells) of the body's immune response. It injects virus genetic material into the blood cell, causing the cell to form new HIV viruses. Once formed, these new viruses bud out of the T-cell, damaging the cell membrane. This is a possible way in which the T-cell is destroyed, weakening the body's immune system, and leading to the symptoms of AIDS. Magnification: unknown.