Structural Basis for Broad HIV-1 Neutralization by the MPER-Specific Human Broadly Neutralizing Antibody LN01

Dora Pinto,François Dehez,Maciej Tarkowski,Sonia Barbieri,Christophe Caillat,Olivier Schwartz,Timothée Bruel,Georgia D Tomaras,Andrea Minola,Michael S Seaman,Christophe Chipot,Agostino Riva,David Jarrossay,Giuseppe Pantaleo,Xiaoying Shen,Serafima Guseva,Antonio Lanzavecchia,Jérémy Dufloo,Chiara Silacci,Craig Fenwick,David C Montefiori,Davide Corti,Winfríed Weissenhorn

doi:10.1016/j.chom.2019.09.016

Abstract

SummaryPotent and broadly neutralizing antibodies (bnAbs) are the hallmark of HIV-1 protection by vaccination. The membrane-proximal external region (MPER) of the HIV-1 gp41 fusion protein is targeted by the most broadly reactive HIV-1 neutralizing antibodies. Here, we examine the structural and molecular mechansims of neutralization by anti-MPER bnAb, LN01, which was isolated from lymph-node-derived germinal center B cells of an elite controller and exhibits broad neutralization breadth. LN01 engages both MPER and the transmembrane (TM) region, which together form a continuous helix in complex with LN01. The tilted TM orientation allows LN01 to interact simultaneously with the peptidic component of the MPER epitope and membrane via two specific lipid binding sites of the antibody paratope. Although LN01 carries a high load of somatic mutations, most key residues interacting with the MPER epitope and lipids are germline encoded, lending support for the LN01 epitope as a candidate for lineage-based vaccine development.

Highlights

LN01 Isolation and Characterization Among a cohort of chronically HIV-1-infected patients, naıve to antiretroviral therapy, we identified a patient (SA003) who showed high level of serum bnAbs, as assessed on a panel of 9 HIV-1 pseudoviruses (PVs) from the Global Panel of HIV-1 Env reference strains (Figure S1A)
SA003 donor is an elite controller with viremia
The two B cell subsets were immortalized with Epstein-Barr virus (EBV) in the presence of anti-B-cell-receptor polyclonal antibodies and cultured for 14 days on a monolayer of mesenchymal stromal cells (MSCs) together with a cocktail of stimuli composed of IL2, IL21, IL6, and the TLR-9 agonist CpG-2006

Summary

Methods

B-cell Isolation and Stimulation Memory and GC B cells from patient SA003 were isolated from cryopreserved lympho node mononuclear cells (LNMCs) as follows: LNMCs were stained with anti-human CD19 PE-Cy7 (BD Bioscience_341113), anti-human IgM FITC (Invitrogen_A21215), anti-human IgA FITC (Invitrogen_A18788), anti-human CD27 BV650 (Biolegend_302827), anti-human CD38 APC (Beckman Coulter_555462) and anti-human CD14 PC5 (Beckman Coulter_A07765) plus anti-human CD3 PC5 (Beckman Coulter_A07749) on ice for 20 min. Memory IgG+ B cells were sorted as CD19+CD27+CD38- while GC IgG+ B cells as CD19+CD27+CD38+, both negative for all other markers, resuspended in complete IMDM with 10% FBS and immortalized with Epstein-Barr virus (EBV) in the presence of 2.5 mg/ml CpG 2006, 2.5 mg/ml AffiniPure F(ab’) Fragment Goat Anti-Human IgA+IgG+IgM (H+L) (Jackson Immunoresearch), 500 U/ml IL-2, 5 ng/ml IL-6 (BD Pharmingen) and 10 ng/ml IL-21 (ImmunoTolls). The B cells that neutralized four out of four HIV-1 PVs were lysed and the variable regions of the heavy and light chain were cloned

Results

Discussion

Conclusion