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Characterization of human monoclonal antibodies selected with a hypervariable loop-deleted recombinant HIV-1(IIIB)
S A Jeffs1, M K Gorny, C Williams
1Division of Retrovirology, NIBSC, Blanche Lane, South Mimms, Potters Bar, EN6 3QG, Herts, UK. sjeffs@nibsc.ac.uk
Immunology Letters
|October 16, 2001
Summary
Researchers engineered the PR12 protein from HIV-1 gp120 to expose the CD4 binding domain (CD4bd). This facilitated the generation of human monoclonal antibodies (MAbs) targeting conserved and clade-specific epitopes, aiding in HIV-1 vaccine development.
Area of Science:
- Immunology
- Virology
- Structural Biology
Background:
- The HIV-1 envelope glycoprotein gp120 contains a critical CD4 binding domain (CD4bd) essential for viral entry.
- The accessibility of CD4bd epitopes is often masked in the native gp120 structure, posing challenges for antibody-mediated neutralization.
- Recombinant proteins can be engineered to enhance epitope exposure for antibody selection.
Purpose of the Study:
- To develop a modified gp120 protein (PR12) with enhanced CD4 binding domain (CD4bd) exposure.
- To generate and characterize human monoclonal antibodies (MAbs) targeting CD4bd epitopes using the PR12 protein.
- To assess the specificity and conservation of anti-CD4bd MAbs across different HIV-1 clades.
Main Methods:
- Site-directed mutagenesis was used to create the PR12 protein, deleting C-terminal amino acids and V1-V3 loops from HIV-1(IIIB) gp120.
- Human MAbs were selected using PR12 as an immunogen from HIV-1 infected individuals.
- Antibody specificity was determined by binding assays against recombinant envelope proteins from various HIV-1 clades and by sequence analysis of antibody variable regions.
Main Results:
- The PR12 protein exhibited significantly increased CD4bd exposure compared to wild-type gp120.
- Five human MAbs (1570A, 1570C, 1570D, 1595, 1599) were generated, with three (1570A, C, D) representing a single MAb lineage.
- MAb 1599 showed clade B specificity, MAb 1595 reacted with clades A, B, and D, and MAb 1570 recognized a conserved epitope binding all tested clades.
Conclusions:
- The engineered PR12 protein effectively serves as an immunogen for inducing anti-CD4bd antibodies.
- PR12 selection yields MAbs with distinct specificities, including broadly conserved and clade-specific targets within the CD4bd.
- These findings highlight the potential of PR12 for developing immunogens aimed at eliciting broadly neutralizing antibodies against HIV-1.