In 1991, AIDSVAX originally consisted of the B envelope of recombinant gp120, a glycoprotein unique to HIV's surface, from a strain of the virus, MN, known at the time to infect people in the United States and Europe.
The vaccine was designed to provoke the production of antibodies in subjects that would strip the gp120 protein off of the HIV viral particles, effectively disabling the virus so that it could not bind to or invade susceptible cells.
[2] VaxGen's leadership enthusiastically applied to the U.S. Food and Drug Administration (FDA) for permission to undertake Phase III studies in the U. S. on large numbers of at-risk volunteers.
[2] In response, VaxGen turned to the international community, seeking a place that would sanction clinical trials of AIDSVAX, and after negotiating with AIDS-plagued officials in Africa and Asia, landed upon Thailand.
Initial Phase II trials of AIDSVAX B/B alone in the US and AIDVAX B/E alone in Thailand were unsuccessful, with both vaccines failing to either prevent or weaken HIV infection,[3] so instead VaxGen began Thai trials of AIDSVAX B/E in combination with the Aventis-Pasteur vaccine, ALVAC-HIV, that uses genetic elements of several different HIV strains encapsulated in a canarypox virus vector.