Convergent HIV-1 Evolution upon Targeted Destabilization of the gp120-gp41 Interface

Area of Science:

• Virology
• Immunology
• Structural Biology

Background:

• The human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) trimer is crucial for viral entry and the primary target for neutralizing antibodies.
• HIV-1 Env is metastable and conformationally flexible due to weak inter-subunit interactions, posing challenges for vaccine development.
• Current strategies to stabilize Env trimers include structure-based design and high-throughput screening.

Purpose of the Study:

• To investigate the capacity of directed virus evolution to stabilize the HIV-1 Env trimer.
• To identify specific regions and mutations that confer enhanced Env trimer stability through compensatory evolution.

Main Methods:

• Deliberate destabilization of the Env gp120-gp41 interface via mutagenesis in replicating HIV-1.
• Passaging the mutated virus to allow for evolutionary adaptation and identification of compensatory mutations.
• Analysis of mutation locations and their impact on Env trimer stability, including testing in recombinant soluble Env trimers.

Main Results:

• Directed evolution identified compensatory mutations that overcome initial Env destabilization.
• Convergent evolution was observed, with mutations frequently occurring in the V1V2 domain of gp120 and the HR1/HR2 domains of gp41.
• Specific mutations, such as S614G and Q567R, were recurrent, strengthening inter-subunit interactions and enhancing trimer stability.
• Selected mutations improved the stability of recombinant soluble Env trimer proteins.

Conclusions:

• Directed viral evolution is a viable strategy to study and enhance HIV-1 Env trimer stability.
• Compensatory mutations cluster in specific Env regions, highlighting their critical roles in maintaining trimer integrity.
• Understanding these stabilizing mechanisms provides valuable insights for designing more effective HIV-1 vaccine immunogens.