Synthetic Peptides Derived from the Variable Regions of an Anti-CD4 Monoclonal Antibody Bind to CD4 and Inhibit HIV-1 Promoter Activation in Virus-infected Cells

Abstract

The monoclonal antibody (mAb) ST40, specific for the immunoglobulin complementarity-determining region (CDR) 3-like loop in domain 1 of the CD4 molecule, inhibits human immunodeficiency virus type 1 (HIV-1) promoter activity and viral transcription in HIV-infected cells. To design synthetic peptides from the ST40 paratope that could mimic these biological properties, a set of 220 overlapping 12-mer peptides frameshifted by one residue, corresponding to the deduced ST40 amino acid sequence, was synthesized by the Spot method and tested for binding to recombinant soluble CD4 antigen. Several peptides that included in their sequences amino acids from the CDRs of the antibody and framework residues flanking the CDRs were found to bind soluble CD4. Eleven paratope-derived peptides (termed CM1-CM11) were synthesized in a cyclic and soluble form. All the synthetic peptides showed CD4 binding capacity with affinities ranging from 1.6 to 86.4 nM. Moreover, peptides CM2, CM6, CM7, CM9, and CM11 were able to bind a cyclic peptide corresponding to the CDR3-like loop in domain 1 of CD4 (amino acids 81-92 of CD4). Peptide CM9 from the light chain variable region of mAb ST40 and, to a lesser extent, peptides CM2 and CM11 were able to inhibit HIV-1 promoter long terminal repeat-driven ␤-galactosidase gene expression in the HeLa P4 HIV-1 long terminal repeat ␤-galactosidase indicator cell line infected with HIV-1. The binding of mAb ST40 to CD4 was also efficiently displaced by peptides CM2, CM9, and CM11. Our results indicate that the information gained from a systematic exploration of the antigen binding capacity of synthetic peptides from immunoglobulin variable sequences can lead to the identification of bioactive paratope-derived peptides of potential pharmacological interest.

Probing the origins, diagnosis and treatment of amyloid diseases using antibodies

“…Sequences corresponding of the paratope (i.e. the region of the antibody reacting with the antigen) of such antibodies can be used as lead to the rational design of small-molecule drugs [106]. Textbox 2 Diagnostic tests of BSE.…”

The Monoclonal Antibody 1F6 Identifies a pH-dependent Conformational Change in the Hydrophilic NH2 Terminus of NhaA Na+/H+ Antiporter ofEscherichia coli

“…Assay for mAb 1F6 Interaction with Cellulose-bound Peptides-The technique was performed as described previously for epitope analysis (27). The saturated membrane was incubated with 12 g/ml mAb 1F6 solution in the blocking buffer (Genosys Biotechnologies, UK) for 2 h at room temperature.…”

“…For each run mAb 1F6 and His-tagged NhaA, 20 g each, were mixed in the respective buffers and incubated for 30 min at 4°C. Peptide Synthesis on Cellulose Membranes-The general protocol has been described previously (27). Membranes were obtained from Abimed (Langenfeld, Germany); Fmoc amino acids and N-hydroxybenzotriazole were obtained from Nova Biochem (Lä ufelfingen, Switzerland).…”

A Cell-penetrating Antibody Fragment against HIV-1 Rev Has High Antiviral Activity

“…Monoclonal antibodies and their derivatives, such as antigen binding fragments (Fab) 2 and the corresponding complementarity determining region (CDR) peptides, have been described as plausible agents for inhibiting HIV-1. These have been directed either against gp120, the envelope glycoprotein, or more commonly, the CD4 receptor (2)(3)(4)(5)(6)(7)(8). All have shown promise.…”