HIV type 1 Env precursor cleavage state affects recognition by both neutralizing and nonneutralizing gp41 antibodies

Area of Science:

• Immunology
• Virology
• Structural Biology

Background:

• HIV-1 is challenging to neutralize due to its resistant envelope glycoproteins (Env).
• Specific antibodies targeting gp120 and gp41 can neutralize diverse HIV-1 isolates.
• The membrane proximal external region (MPER) of gp41 is a target for broadly neutralizing antibodies like 2F5 and 4E10.

Purpose of the Study:

• To investigate the recognition of cleaved vs. cleavage-defective HIV-1 Env spikes by gp41-specific antibodies.
• To compare the binding patterns of neutralizing and non-neutralizing gp41 antibodies to different Env spike forms.
• To understand the influence of Env spike cleavage on antibody binding kinetics and quaternary structure.

Main Methods:

• Site-directed mutagenesis to create cleavage-defective HIV-1 Env spikes.
• Analysis of antibody binding to cleaved and non-cleaved JR-FL Env spikes.
• Assessment of antibody recognition following CD4 interaction with Env spikes.

Main Results:

• Non-neutralizing gp41 antibodies bound better to cleavage-defective spikes than cleaved spikes.
• Broadly neutralizing gp41 antibodies (2F5, 4E10) showed limited recognition of cleaved JR-FL spikes.
• Cleavage-defective spikes significantly enhanced recognition by both neutralizing and non-neutralizing gp41 antibodies.
• CD4 binding increased non-neutralizing gp41 antibody recognition but minimally affected 2F5 and 4E10 recognition.

Conclusions:

• HIV-1 Env spike cleavage profoundly influences the quaternary structure and antibody recognition landscape.
• The binding of broadly neutralizing gp41 antibodies is sensitive to the cleavage status of the Env spike.
• Findings have implications for designing effective soluble trimer immunogens for HIV-1 vaccine development.