When I first became aware of AIDS my knee-jerk guess was an experiment
gone wrong like with the "killer bees", for example. At the time I even
considered the possibility that it could have been a military,
biological-weapon experiment. Like with the killer bees, it just didn't
seem likely to me that something like this could have happened without
some sort of man-made intervention with mother nature.

There is a theory by a Dr. Leonard Horowitz that the HIV infection was
a result of a hepatitis B vaccine. So, my first guess might still turn
out to be right.

http://www.originofaids.com/