A class of organic compounds which contain two rings that share a pair of bridgehead carbon atoms.

Includes the spectrum of human immunodeficiency virus infections that range from asymptomatic seropositivity, thru AIDS-related complex (ARC), to acquired immunodeficiency syndrome (AIDS).

Development of neutralizing antibodies in individuals who have been exposed to the human immunodeficiency virus (HIV/HTLV-III/LAV).

Studies of the number of cases where human immunodeficiency virus (HIV) is present in a specific population at a designated time. The presence in a given individual is determined by the finding of HIV antibodies in the serum (HIV SEROPOSITIVITY).

Immune status consisting of non-production of HIV antibodies, as determined by various serological tests.