AIDS (Acquired ImmunoDeficiency Syndrome) has become a major world-wide epidemic. AIDS is caused by the human immunodeficiency virus (HIV). By killing or damaging cells of the body's immune system, HIV progressively destroys the body's ability to fight infections and certain cancers. People diagnosed with AIDS may get life-threatening diseases called opportunistic infections, which are caused by microbes such as viruses or bacteria that usually do not make healthy people sick. The term AIDS applies to the most advanced stages of HIV infection. During the past 10 years, however, researchers have developed drugs to fight both HIV infection and its associated infections and cancers. The first group of drugs used to treat HIV infection, called nucleoside reverse transcriptase (RT) inhibitors, interrupts an early stage of the virus making copies of itself. A second class of drugs for treating HIV infection is called protease inhibitors, which interrupt virus replication at a later step in its life cycle. Research is extremely active in all areas of HIV infection, including developing and testing preventive HIV vaccines and new treatments for HIV infection and AIDS - associated opportunistic infections. Researchers also are investigating how exactly HIV damages the immune system. This research is identifying new and more effective targets for drugs and vaccines. This new book includes in its scope the prevention, pathogenesis, diagnosis and treatment of this disease.