Screening method for the identification of agents capable of activating CD4+CD25+ regulatory T-cells through interactions with the HIV-1 GP120 binding site on CD4

A method according to claim 1 wherein step (a) of claim 16 comprises:

• (a) providing a first solution comprising CD4,
• (b) providing a second solution comprising CD4,
• (c) adding to the first solution a substance to be tested and HIV-1 gp120 under conditions which allow binding of HIV-1 gp120 with CD4,
• (d) adding to the second solution HIV-1 gp120 under conditions like
• (c) allowing binding of HIV-1 gp120 with CD4,
• (e) measuring in the first and in the second solution whether the HIV-1 gp120 has bound to the CD4 wherein a reduced amount of bound HIV-1 gp120 in the first solution indicates that the substance can interact with HIV-1 gp120-binding site of CD4.

A method for determining whether a substance can activate a regulatory T cell (Treg) via interaction with the epitope as set forth in SEQ ID NO:

• 1 comprising:
• (a) providing a first solution comprising a CD4+CD25+ Treg cell,
• (b) adding a substance to be tested under conditions which allow interaction of the substance with a CD4+CD25+ Treg cell,
• (c) measuring whether a CD4+CD25+ Treg cell of the first solution has been activated,
• (d) providing a second solution comprising a CD4+CD25+ Treg cell,
• (e) adding the substance to be tested and a peptide comprising an amino acid sequence as set forth in SEQ ID NO:
• 1 under conditions like (b),
• (f) measuring whether a CD4+CD25+ Treg cell of the second solution has been activated,
• (g) comparing results obtained from (c) with those obtained from
• (f) wherein a reduced activation of (f) identifies the substance as a Treg cell activator which activates a CD4+CD25+ Treg cell via interaction with the epitope as set forth in SEQ ID NO:
• 1.

A method according to claim 19 wherein in step (e) of claim 34 the peptide used is selected from a group consisting of an isolated peptide spanning amino acid No. 1-31 of SEQ ID NO 1, No. 26 to 458 of SEQ ID NO.:

• 2, No. 26 to 419 of SEQ ID NO.:2, No. 26 to 207 of SEQ ID NO.:
• 2, No. 26 to 131 of SEQ ID NO.:
• 2 and No. 46 to 89 of SEQ ID NO.:
• 2.