Induction of tier-2 neutralizing antibodies in mice with a DNA-encoded HIV envelope native like trimer

Ziyang Xu,Ishaan Patel,Lauren Gites,Faraz I Zaidi,Laurent Humeau,April Obeirne,Yuanhan Wu,Jesper Pallesen,Neethu Chokkalingam,Mansi Purwar,Alan W Moore ,Abhijeet J Kulkarni ,Trevor R.f Smith ,David B Weiner ,Megan C Wise ,Kate E Broderick ,Kylie M Konrath ,Edgar Tello‐Ruiz ,Nicholas J Tursi ,Emma L Reuschel ,Janess Mendoza,Susanne Walker,Jianqiu Du,Katherine Schultheis,Sonali Majumdar,Daniel W Kulp

doi:10.1038/s41467-022-28363-z

Abstract

HIV Envelope (Env) is the main vaccine target for induction of neutralizing antibodies. Stabilizing Env into native-like trimer (NLT) conformations is required for recombinant protein immunogens to induce autologous neutralizing antibodies(nAbs) against difficult to neutralize HIV strains (tier-2) in rabbits and non-human primates. Immunizations of mice with NLTs have generally failed to induce tier-2 nAbs. Here, we show that DNA-encoded NLTs fold properly in vivo and induce autologous tier-2 nAbs in mice. DNA-encoded NLTs also uniquely induce both CD4 + and CD8 + T-cell responses as compared to corresponding protein immunizations. Murine neutralizing antibodies are identified with an advanced sequencing technology. The structure of an Env-Ab (C05) complex, as determined by cryo-EM, identifies a previously undescribed neutralizing Env C3/V5 epitope. Beyond potential functional immunity gains, DNA vaccines permit in vivo folding of structured antigens and provide significant cost and speed advantages for enabling rapid evaluation of new HIV vaccines.

Highlights

HIV Envelope (Env) is the main vaccine target for induction of neutralizing antibodies
Using binding ELISA, expressed BG505.MD39 was shown to bind to broadly neutralizing antibodies (bNAbs) PGT145, which preferentially recognizes the trimeric conformational epitope on Env V2-apex[34], but not non-NAb 3074, which is specific for the Env V3 loop which is an epitope exposed on monomeric gp[140] but hidden in a NLT35–37 (Fig. 1b)
To further assess the antigenic profile including glycan-sensitive antibodies of in vivo produced versus recombinant native-like trimer (NLT), we have developed and performed Antigen Conformation Tracing In Vivo by ELISA (ACTIVE) to compare in vivo produced versus recombinant MD39 or gp120-foldon in binding to HIV antibodies

Summary

Introduction

HIV Envelope (Env) is the main vaccine target for induction of neutralizing antibodies. Stabilizing Env into native-like trimer (NLT) conformations is required for recombinant protein immunogens to induce autologous neutralizing antibodies(nAbs) against difficult to neutralize HIV strains (tier-2) in rabbits and non-human primates. Several modifications have been found to allow the folding and production of trimer proteins that resemble the native viral Env conformations, or native-like trimers (NLTs)[7–11] Biophysical techniques such as cryo-electron microscopy (cryo-EM) and X-ray crystallography of various identified broadly neutralizing antibodies (bNAbs) bound to NLTs confirmed that these NLTs can present important conformational neutralizing epitopes in a solvent-accessible fashion[8,12]. While early studies demonstrated the immunogenicity of DNA vaccines in larger animals and humans was sub-optimal, advances in antigen design, nucleic acid formulations, genetic adjuvants, and adaptive electroporation (EP) technologies have enabled DNA vaccines to induce more potent and consistent responses in several clinical studies, including Zika, MERS and Ebola[24–26]. We have demonstrated that DNA/EP can be used for direct in vivo delivery of highly-folded monoclonal antibodies and biologics[28–30], and to launch de novo assembly of more complex nanoparticle vaccines in the hosts to induce immune responses phenotypically different from protein nanoparticle vaccines[31]

Methods

Results

Conclusion