SOSIP Trimer-Specific Antibodies Isolated from a Simian-Human Immunodeficiency Virus-Infected Monkey with versus...

Area of Science:

• Immunology and Virology
• Antibody Engineering
• HIV-1 Research

Background:

• The BG505 SOSIP.664 (SOSIP) trimer is a stabilized mimic of the HIV-1 envelope spike, valuable for isolating neutralizing antibodies.
• Previous methods using SOSIP sometimes yielded non-neutralizing antibodies, including those targeting the gp41 external domain.
• Developing strategies to isolate potent, broadly neutralizing antibodies is crucial for HIV-1 prophylaxis and therapy.

Purpose of the Study:

• To optimize the isolation of neutralizing monoclonal antibodies (MAbs) against HIV-1 using the SOSIP trimer.
• To investigate the impact of a gp41 blocking step on MAb isolation efficiency and specificity.
• To increase the yield of non-gp41-reactive, SOSIP-specific MAbs with neutralizing activity.

Main Methods:

• Screened serum from SHIV-AD8 infected rhesus monkeys for neutralizing activity against various HIV-1 strains.
• Isolated MAbs using fluorescence-activated cell sorting (FACS) with the SOSIP trimer as a probe.
• Implemented a gp41 blocking step prior to PBMC staining and FACS sorting in a second isolation round.

Main Results:

• An initial sort yielded many gp41-specific, non-neutralizing MAbs.
• The second sort, with a gp41 pre-blocking step, significantly increased the proportion of neutralizing MAbs.
• Isolated MAbs in the second round were SOSIP-specific and not directed to the gp41 external domain.

Conclusions:

• Pre-blocking with gp41 recombinant protein effectively reduces the isolation of non-neutralizing, gp41-specific antibodies.
• This strategy significantly enhances the yield of SOSIP-specific MAbs with neutralizing activity.
• The optimized method improves the likelihood of isolating broadly neutralizing antibodies for HIV-1 therapeutic and prophylactic applications.