Our understanding of Acquired Immune Deficiency Syndrome ( AIDS) and Human Immune Deficiency Virus ( HIV) has undergone rapid progress. Still, gaps in our understanding have prevented us from developing the ideal therapy or vaccine. Should we panic? The answer is no. Education has caused a decrease in the spread of AIDS in certain high-risk populations, and current therapies and vaccines add confidence that more effective treatments will be developed.

AIDS therapies have been difficult to develop for several reasons. Retroviruses, such as HIV, can integrate directly into the genetic material of the host cell. The virus can then go undetected for extended periods of time. HIV also infects a large variety of tissue and cells within the body. In particular, the virus can enter the nervous system where it is protected by the blood-brain barrier, which many helpful drugs cannot penetrate. Secondary diseases...