Mapping polyclonal serum responses is critical to rational vaccine design. However, most high-resolution mapping approaches involve isolating and characterizing individual antibodies, which incompletely defines the polyclonal response. Here we use two complementary approaches to directly map the specificities of the neutralizing and binding antibodies of polyclonal anti-HIV-1 sera from rabbits immunized with BG505 Env SOSIP trimers. We used mutational antigenic profiling to determine how all mutations in Env affected viral neutralization and electron microscopy polyclonal epitope mapping (EMPEM) to directly visualize serum Fabs bound to Env trimers. The dominant neutralizing specificities were generally only a subset of the more diverse binding specificities. Additional differences between binding and neutralization reflected antigenicity differences between virus and soluble Env trimer. Further, we refined residue-level epitope specificity directly from sera, revealing subtle differences across sera. Together, mutational antigenic profiling and EMPEM yield a holistic view of the binding and neutralizing specificity of polyclonal sera.
- Jesse D Bloom
- John P Moore
- Andrew B Ward
- Julie M Overbaugh
- Jesse D Bloom
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Pamela J Bjorkman, California Institute of Technology, United States
- Received: October 22, 2020
- Accepted: January 12, 2021
- Accepted Manuscript published: January 13, 2021 (version 1)
© 2021, Dingens et al.
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