Redesigned HIV antibodies exhibit enhanced neutralizing potency and breadth
Jordan R. Willis, … , Jens Meiler, James E. Crowe Jr.
Jordan R. Willis, … , Jens Meiler, James E. Crowe Jr.
Published May 18, 2015
Citation Information: J Clin Invest. 2015;125(6):2523-2531. https://doi.org/10.1172/JCI80693.
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Research Article AIDS/HIV

Redesigned HIV antibodies exhibit enhanced neutralizing potency and breadth

Abstract

Several HIV envelope-targeting (Env-targeting) antibodies with broad and potent neutralizing activity have been identified and shown to have unusual features. Of these, the PG9 antibody has a long heavy chain complementarity determining region 3 (HCDR3) and possesses unique structural elements that interact with protein and glycan features of the HIV Env glycoprotein. Here, we used the Rosetta software suite to design variants of the PG9 antibody HCDR3 loop with the goal of identifying variants with increased potency and breadth of neutralization for diverse HIV strains. One variant, designated PG9_N100FY, possessed increased potency and was able to neutralize a diverse set of PG9-resistant HIV strains, including those lacking the Env N160 glycan, which is critical for PG9 binding. An atomic resolution structure of the PG9_N100FY fragment antigen binding (Fab) confirmed that the mutated residue retains the paratope surface when compared with WT PG9. Differential scanning calorimetry experiments revealed that the mutation caused a modest increase in thermodynamic stability of the Fab, a feature predicted by the computational model. Our findings suggest that thermodynamic stabilization of the long HCDR3 in its active conformation is responsible for the increased potency of PG9_N100FY, and strategies aimed at stabilizing this region in other HIV antibodies could become an important approach to in silico optimization of antibodies.

Authors

Jordan R. Willis, Gopal Sapparapu, Sasha Murrell, Jean-Philippe Julien, Vidisha Singh, Hannah G. King, Yan Xia, Jennifer A. Pickens, Celia C. LaBranche, James C. Slaughter, David C. Montefiori, Ian A. Wilson, Jens Meiler, James E. Crowe Jr.

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Figure 2

Rosetta redesigned mutants exhibit increased breadth and potency against HIV.

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Rosetta redesigned mutants exhibit increased breadth and potency against...
Binding and neutralization profiles for the characterized PG9 mutants. Antibody mutants are shown using Kabat numbering. The virus name is shown in the left column, and amino acid sequence for position 160 (HIV strain HXBc2 numbering) is shown in the second column. Strains lacking a potential N-linked glycosylation site are indicated with bold rows. A yellow-to-green color scale indicates ranges of values, from less than 0.01 μg/ml to greater than 100 μg/ml, respectively, for concentrations needed for half maximum signal in ELISA (EC50) in the left panel. A yellow-to-green scale from 0.4 ng/ml to greater than 33 μg/ml, respectively, is shown for half-maximal concentration needed to inhibit virus infection (IC50), in the right panel. Each ELISA experiment was done in triplicate, and neutralization was done in duplicate. A Wilcoxon test was used to determine if the distributions for binding and neutralization were statistically significant from WT PG9. The P value for comparison of each variant against WT PG9 (comparing the pattern of results in a single variant antibody column against the results in the left column for WT PG9) is shown at the bottom of the panels and reflects a 2-sided significance at a level of 0.05.