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Original Research ARTICLE

Front. Immunol. | doi: 10.3389/fimmu.2020.01529

The effects of framework mutations at the variable domain interface on antibody affinity maturation in an HIV-1 broadly neutralizing antibody lineage Provisionally accepted The final, formatted version of the article will be published soon. Notify me

  • 1Swarthmore College, United States

Understanding affinity maturation of antibodies that can target many variants of HIV-1 is important for vaccine development. While the antigen-binding site of antibodies is known to mutate throughout the co-evolution of antibodies and viruses in infected individuals, the roles of the mutations in the antibody framework region are not well understood. Throughout affinity maturation, the CH103 broadly neutralizing antibody lineage, from an individual designated CH505, altered the orientation of one of its antibody variable domains. The change in orientation was a response to insertions in the variable loop 5 (V5) of the HIV envelope. In this study, we generated CH103 lineage antibody variants in which residues in the variable domain interface were mutated, and measured the binding to both autologous and heterologous HIV-1 envelopes. Our data show that very few mutations in an early intermediate antibody of the lineage can improve binding towards both autologous and heterologous HIV-1 envelopes. We also crystallized an antibody mutant to show that framework mutations alone can result in a shift in relative orientations of the variable domains. Taken together, our results demonstrate the functional importance of residues located outside the antigen-binding site in affinity maturation.

Keywords: Human immunodeficiency virus (HIV), antibody, evolution, crystal structure, somatic hypermutation, framework

Received: 11 Feb 2020; Accepted: 10 Jun 2020.

Copyright: © 2020 Fera, Zhou, Zaidi and Ton. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Daniela Fera, Swarthmore College, Swarthmore, United States, dfera1@swarthmore.edu