Secondly, AIDS is caused by the human immunodeficiency virus, or HIV. This virus attacks the antibodies in a person’s immune system, thereby disabling that system. HIV works in an unusual way because it uses the immune system to its advantage. Viruses cannot live unless they are inside of a living cell called a host. The virus uses the host cell to reproduce themselves, causing the cell to die in the process. The new virii are then set free. The HIV virus attacks T4 lymphocytes, which are a special type of white blood cell. These cells are the body’s method of defense. Without them, humans are susceptible to disease and infection. It is not HIV that kills people, but the opportunistic infections people get because of a weakened immune system. Bevan characterizes HIV by saying, “It’s the sneakiest virus of all. It goes for the crucial link in the immune system, the cells at the heart of the fightback effort” (Bevan 24). This is why HIV is so dangerous.