There is no cure for HIV infection or AIDS, and drug therapy is too expensive for most affected populations. For this reason, the development of safe, effective vaccines to prevent HIV infections worldwide is needed. ALVAC vCP1452 and MN rgp120/HIV-1 have been shown to be well tolerated in Phase I and II studies. ALVAC vCP1452 given alone or in combination with subunit antigens [AS PER AMENDMENT 10/12/00: antigen] is a candidate vaccine to be evaluated for the ability to produce and express vaccine antigen in greater quantity for a longer time and with improved immunogenicity.