In 1981, the first cases of acquired immunodeficiency syndrome (AIDS) were described in American homosexual men. Thereafter, within three short years, French and American scientists confirmed that the human immunodeficiency virus (HIV) is the causative agent for AIDS. In the ensuing 20 years, >20 million individuals have died from AIDS; and currently, in 2006, 50 million people worldwide are infected by HIV-1 with 3 million incremental AIDS deaths and 4-5 million new infections occurring annually. The magnitude of this burden casts urgency to medical research on HIV/AIDS.