Abstract: Compositions which comprise one or more B epitopes of the envelope glycoprotein of a retrovirus and one or more T epitope of the envelope glycoprotein from a distinct retrovirus, or a Tepitope from a different protein of the same retrovirus as the B epitope. In particular, the retrovirus is a human immunodeficiency virus (HIV) or a simian immunodeficiency virus (SIV), human T-cell lymphotropic virus type I (HTLV-I), or a human T-cell lymphotropic virus type II (HTLV-II).

Abstract: Compositions comprise one or more B epitopes of the envelope glycoprotein of a retrovirus and one or more T epitopes of the envelope glycoprotein from a distinct retrovirus, or a T epitope from a different protein of the same retrovirus as the B epitope. In particular, the retrovirus is a human immunodeficiency virus (HIV) or a simian immunodeficiency virus (SIV), human T-cell lymphotropic virus type 1 (HTLVI), or human T-cell lymphotropic virus type II (HTLVII).

Abstract: The present invention teaches multiple branch peptide constructions (MBPCs) formed from a core matrix to which is attached peptides derived from the V3 loop of the envelope glycoprotein of HIV-1, and including the amino acid sequence GPGR (SEQ ID NO: 5), preferably in the form GPGRAF, but which peptides preferably are free of the amino acid sequences IGPGR (SEQ ID NO: 1) or IXXGPGR (SEQ ID NO: 3), where X is an amino acid residue, and the use of such MBPCs as a therapy against HIV. The MBPCs prevent virus/cell infection and cell-to-cell virus transmission between CD4.sup.+ cells and HIV without hindering the immunogenic role of the CD4.sup.+ cells. Moreover, the MBPCs are effective in blockading both CD4 receptors on lymphocytes and macrophages and GalCer receptors on colon epithelial cells. These MBPCs are not immunogenic nor toxic at doses of their intended use (<[10.sup.-3 M]), thus allowing for them to be used therapeutically.