A Panel of IgG1 b12 Variants with Selectively Diminished or Enhanced Affinity for Fcγ Receptors To Define the Role of Effector Functions in Protection against HIV

Brian Moldt,Jackson D Harvey,Niccole Schultz,Michael D Alpert,Pascal Poignard,Dennis R Burton,D Cameron Dunlop,Ann J Hessell,David T Evans

doi:10.1128/jvi.05541-11

Brian Moldt, Jackson D Harvey + Show 7 more

Open Access

PDF Available

https://doi.org/10.1128/jvi.05541-11

Copy DOI

Export

Save

Cite

Abstract
Highlights/Summary
Full-Text PDF
Similar Papers

Abstract

Listen

Passive transfer of neutralizing antibodies is effective in protecting rhesus macaques against simian/human immunodeficiency virus (SHIV) challenge. In addition to neutralization, effector functions of the crystallizable fragment (Fc) of antibodies are involved in antibody-mediated protection against a number of viruses. We recently showed that interaction between the Fc fragment of the broadly neutralizing antibody IgG1 b12 and cellular Fcγ receptors (FcγRs) plays an important role in protection against SHIV infection in rhesus macaques. The specific nature of this Fc-dependent protection is largely unknown. To investigate, we generated a panel of 11 IgG1 b12 antibody variants with selectively diminished or enhanced affinity for the two main activating FcγRs, FcγRIIa and FcγRIIIa. All 11 antibody variants bind gp120 and neutralize virus as effectively as does wild-type b12. Binding studies using monomeric (enzyme-linked immunosorbent assay [ELISA] and surface plasmon resonance [SPR]) and cellularly expressed Fcγ receptors show decreased (up to 5-fold) and increased (up to 90-fold) binding to FcγRIIa and FcγRIIIa with this newly generated panel of antibodies. In addition, there was generally a good correlation between b12 variant affinity for Fcγ receptor and variant function in antibody-dependent cell-mediated virus inhibition (ADCVI), phagocytosis, NK cell activation assays, and antibody-dependent cellular cytotoxicity (ADCC) assays. In future studies, these b12 variants will enable the investigation of the protective role of individual FcγRs in HIV infection.

Highlights

Passive transfer of neutralizing antibodies is effective in protecting rhesus macaques against simian/human immunodeficiency virus (SHIV) challenge
We recently demonstrated that the Fc part of the broadly neutralizing antibody IgG1 b12 plays a crucial role in protection against simian-human immunodeficiency virus (SHIV) infection in rhesus macaques [17, 18]
To enable us to investigate the importance of specific Fc␥ receptors (Fc␥Rs) in the protection against HIV infection, 11 IgG1 b12 variants were generated (Fig. 1)

Summary

Introduction

Passive transfer of neutralizing antibodies is effective in protecting rhesus macaques against simian/human immunodeficiency virus (SHIV) challenge. There was generally a good correlation between b12 variant affinity for Fc␥ receptor and variant function in antibody-dependent cell-mediated virus inhibition (ADCVI), phagocytosis, NK cell activation assays, and antibody-dependent cellular cytotoxicity (ADCC) assays In future studies, these b12 variants will enable the investigation of the protective role of individual Fc␥Rs in HIV infection. We recently demonstrated that the Fc part of the broadly neutralizing antibody IgG1 b12 plays a crucial role in protection against simian-human immunodeficiency virus (SHIV) infection in rhesus macaques [17, 18] In these studies, using b12 variants deficient in Fc␥ receptor (Fc␥R) interaction and complement activation, or complement activation only, we showed that complement activation alone was unimportant but that interaction with Fc␥ receptors was. These studies provide insight into the antibody residues that need to be altered to generate antibodies with specific affinities for individual Fc␥Rs

Methods

Results

Conclusion