Electron-Microscopy-Based Epitope Mapping Defines Specificities of Polyclonal Antibodies Elicited during HIV-1 BG505 Envelope Trimer Immunization

By M. Bianchi, H. Turner, B. Nogal, C. Cottrell, D. Oyen, M. Pauthner, R. Bastidas, R. Nedellec, Laura E. McCoy, Ian A. Wilson and 3 more. 2018

204 citations recorded by the source corpus.

SUMMARY Characterizing polyclonal antibody responses via currently available methods is inherently complex and difficult. Mapping epitopes in an immune response is typically incomplete, which creates a barrier to fully understanding the humoral response to antigens and hinders rational vaccine design efforts. Here, we describe a method of characterizing polyclonal responses by using electron microscopy, and we applied this method to the immunization of rabbits with an HIV‐1 envelope glycoprotein vaccine candidate, BG505 SOSIP.664. We detected known epitopes within the polyclonal sera and revealed how antibody responses evolved during the prime‐boosting strategy to ultimately result in a neutralizing antibody response. We uncovered previously unidentified epitopes, including an epitope proximal to one recognized by human broadly neutralizing antibodies as well as potentially distracting non‐neutralizing epitopes. Our method provides an efficient and semiquantitative map of epitopes that are targeted in a polyclonal antibody response and should be of widespread utility in vaccine and infection studies. Graphical Abstract Figure. No caption available. HighlightsMapped polyclonal epitopes of HIV‐Env‐immunized rabbits via electron microscopyFollowed development and specificity of neutralizing antibodies over timeIdentified a class of antibodies binding between the HIV Env trimer bladesNeutralizing antibody class displays highly convergent structural features &NA; Comprehensive epitope mapping is fundamental to understanding immune responses. Bianchi et al. applied electron microscopy to study polyclonal antibody responses in HIV‐Env‐immunized rabbits. Different antibody specificities were identified and followed over time, revealing the source of neutralization, a distinct class of antibodies, and a highly convergent structural evolution of the neutralizing antibodies.

Subfields: Molecular Biology, Radiology, Nuclear Medicine and Imaging, Virology

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In Molecular Biology

1. Neil P. King
2. Lauren P. Carter
3. David Baker
4. D. Veesler
5. Daniel Ellis
6. M. Kanekiyo
7. Kelly K. Lee
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In Radiology, Nuclear Medicine and Imaging

1. Neil P. King
2. M. Kanekiyo
3. Daniel Ellis
4. David Baker
5. Barney S. Graham
6. Frances H. Arnold

In Virology

1. Neil P. King

Citations in the corpus

• Structures of Human Antibodies Bound to SARS-CoV-2 Spike Reveal Common Epitopes and Recurrent Features of Antibodies (2020, unknown): “In this method, Fabs that bind to an antigenic target are separated from non-binding Fabs in a polyclonal mixture by size-exclusion chromatography (SEC), Fab-antigen complexes are imaged by EM, and 2D/3D classification are used to identify predominant epitopes (Bianchi et al., 2018; Nogal et al., 20”
• Elicitation of broadly protective immunity to influenza by multivalent hemagglutinin nanoparticle vaccines (2020, methodology): “We directly visualized the epitopes recognized by nanoparticle immunogen-elicited antibodies in individual NHPs using recently developed methods for single-particle EM analysis of polyclonal antibody responses 54,55 ​ .”