HIV-1 Env-Dependent Cell Killing by Bifunctional Small-Molecule/Peptide Conjugates

Area of Science:

• Virology
• Medicinal Chemistry
• Structural Biology

Background:

• HIV-1 envelope glycoprotein trimeric complex (Env) is a key target for antiviral therapies.
• Existing therapies often struggle with resistance and complete viral eradication.
• Bifunctional molecules offer a novel approach by engaging multiple viral targets simultaneously.

Purpose of the Study:

• To synthesize and characterize novel bifunctional covalent conjugates targeting HIV-1 Env.
• To evaluate the antiviral activity, including virus inhibition and virion lysis (virolysis).
• To elucidate the mechanism of action, distinguishing between Env-specific and non-specific effects.

Main Methods:

• Synthesis of bifunctional conjugates combining a gp120-binding CD4 mimic (BNM-III-170) and a gp41-binding peptide (Trp3).
• In vitro assays to assess virus inhibition, virion lysis, and cell-based cytotoxicity using flow cytometry.
• Computational modeling to predict binding modes and conformational changes within the Env trimer.

Main Results:

• Bifunctional conjugates inhibited HIV-1 infection with low micromolar potency and induced virion lysis.
• Lysis was dependent on the covalent linkage of the two components, not mere co-administration.
• Cytotoxicity was specific to HIV-1 Env-expressing cells, with Env-negative cells showing no susceptibility.
• Computational modeling indicated tandem binding to gp120 and gp41, inducing conformational changes in Env.

Conclusions:

• The developed small-molecule bifunctional inhibitors specifically trigger Env conformational changes, leading to cell killing.
• This approach demonstrates potential for eliminating HIV-1 infected cells and contributing to viral eradication.
• The findings support further development of bifunctional inhibitors as a strategy against HIV-1.