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Mascola, John R.

Publications and source records attributed to Mascola, John R..

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Antibody-directed evolution reveals a mechanism for enhanced neutralization at the HIV-1 fusion peptide site

The HIV-1 fusion peptide (FP) represents a promising vaccine target, but global FP sequence diversity among circulating strains has limited anti-FP antibodies to ~60% neutralization breadth. Here we evolve the FP-targeting antibody VRC34.01 in vitro to enhance FP-neutralization using site saturation mutagenesis and yeast display. Successive rounds of directed evolution by iterative selection of antibodies for binding to resistant HIV-1 strains establish a variant, VRC34.01_mm28, as a best-in-class antibody with 10-fold enhanced potency compared to the template antibody and ~80% breadth on a cross-clade 208-strain neutralization panel. Structural analyses demonstrate that the improved paratope expands the FP binding groove to accommodate diverse FP sequences of different lengths while also recognizing the HIV-1 Env backbone. These data reveal critical antibody features for enhanced neutralization breadth and potency against the FP site of vulnerability and accelerate clinical development of broad HIV-1 FP-targeting vaccines and therapeutics.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2023

Diverse Murine Vaccinations Reveal Distinct Antibody Classes to Target Fusion Peptide and Variation in Peptide Length to Improve HIV Neutralization

The HIV-1 fusion peptide has been identified as a site for elicitation of broadly neutralizing antibodies, with prior studies demonstrating that priming with fusion peptide-based immunogens and boosting with soluble envelope (Env) trimers can elicit cross-clade HIV-1-neutralizing responses. To improve the neutralizing breadth and potency of fusion peptide-directed responses, we evaluated vaccine regimens that incorporated diverse fusion peptide-conjugates and Env trimers with variation in fusion peptide length and sequence.

Virology↗
DOE OSTI2022

Rare, convergent antibodies targeting the stem helix broadly neutralize diverse betacoronaviruses

Humanity has faced three recent outbreaks of novel betacoronaviruses, emphasizing the need to develop approaches that broadly target coronaviruses. Here, we identify 55 monoclonal antibodies from COVID-19 convalescent donors that bind diverse betacoronavirus spike proteins. Most antibodies targeted an S2 epitope that included the K814 residue and were non-neutralizing. However, 11 antibodies targeting the stem helix neutralized betacoronaviruses from different lineages. Eight antibodies in this group, including the six broadest and most potent neutralizers, were encoded by IGHV1-46 and IGKV3-20. Crystal structures of three antibodies of this class at 1.5–1.75-Å resolution revealed a conserved mode of binding. COV89-22 neutralized SARS-CoV-2 variants of concern including Omicron BA.4/5 and limited disease in Syrian hamsters. Collectively, these findings identify a class of IGHV1-46/IGKV3-20 antibodies that broadly neutralize betacoronaviruses by targeting the stem helix but indicate these antibodies constitute a small fraction of the broadly reactive antibody response to betacoronaviruses after SARS-CoV-2 infection.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2022

Epstein-Barr virus gH/gL has multiple sites of vulnerability for virus neutralization and fusion inhibition

Epstein-Barr virus (EBV) is nearly ubiquitous in adults. EBV causes infectious mononucleosis and is associated with B cell lymphomas, epithelial cell malignancies, and multiple sclerosis. The EBV gH/gL glycoprotein complex facilitates fusion of virus membrane with host cells and is a target of neutralizing antibodies. Here, in this study, we examined the sites of vulnerability for virus neutralization and fusion inhibition within EBV gH/gL. We developed a panel of human monoclonal antibodies (mAbs) that targeted five distinct antigenic sites on EBV gH/gL and prevented infection of epithelial and B cells. Structural analyses using X-ray crystallography and electron microscopy revealed multiple sites of vulnerability and defined the antigenic landscape of EBV gH/gL. One mAb provided near-complete protection against viremia and lymphoma in a humanized mouse EBV challenge model. Our findings provide structural and antigenic knowledge of the viral fusion machinery, yield a potential therapeutic antibody to prevent EBV disease, and emphasize gH/gL as a target for herpesvirus vaccines and therapeutics.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2022

Safety and antiviral activity of triple combination broadly neutralizing monoclonal antibody therapy against HIV-1: a phase 1 clinical trial

HIV-1 therapy with single or dual broadly neutralizing antibodies (bNAbs) has shown viral escape, indicating that at least a triple bNAb therapy may be needed for robust suppression of viremia. We performed a two-part study consisting of a single-center, randomized, double-blind, dose-escalation, placebo-controlled first-in-human trial of the HIV-1 V2-glycan-specific antibody PGDM1400 alone or in combination with the V3-glycan-specific antibody PGT121 in 24 adults without HIV in part 1, as well as a multi-center, open-label trial of the combination of PGDM1400, PGT121 and the CD4-binding-site antibody VRC07-523LS in five viremic adults living with HIV not on antiretroviral therapy (ART) in part 2. The primary endpoints were safety, tolerability and pharmacokinetics for both parts and antiviral activity among viremic adults living with HIV and not on ART for part 2 of the study. The secondary endpoints were changes in CD4 + T cell counts and development of HIV-1 sequence variations associated with PGDM1400, PGT121 and VRC07-523LS resistance in part 2. Intravenously administered PGDM1400 was safe and well-tolerated at doses up to 30 mg kg -1 and when given in combination with PGT121 and VRC07-523LS. A single intravenous infusion of 20 mg kg -1 of each of the three antibodies reduced plasma HIV RNA levels in viremic individuals by a maximum mean of 2.04 log10 copies per ml; however, viral rebound occurred in all participants within a median of 20 days after nadir. Rebound viruses demonstrated partial to complete resistance to PGDM1400 and PGT121 in vitro, whereas susceptibility to VRC07-523LS was preserved. Viral rebound occurred despite mean VRC07-523LS serum concentrations of 93 µg ml -1 . The trial met the pre-specified endpoints. Our data suggest that future bNAb combinations likely need to achieve broad antiviral activity, while also maintaining high serum concentrations, to mediate viral control.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Structural basis of glycan276-dependent recognition by HIV-1 broadly neutralizing antibodies

Recognition of N-linked glycan at residue N276 (glycan276) at the periphery of the CD4-binding site (CD4bs) on the HIV-envelope trimer is a formidable challenge for many CD4bs-directed antibodies. To understand how this glycan can be recognized, here we isolate two lineages of glycan276-dependent CD4bs antibodies. Antibody CH540-VRC40.01 (named for donor-lineage.clone) neutralizes 81% of a panel of 208 diverse strains, while antibody CH314-VRC33.01 neutralizes 45%. Cryo-electron microscopy (cryo-EM) structures of these two antibodies and 179NC75, a previously identified glycan276-dependent CD4bs antibody, in complex with HIV-envelope trimer reveal substantially different modes of glycan276 recognition. Despite these differences, binding of glycan276-dependent antibodies maintains a glycan276 conformation similar to that observed in the absence of glycan276-binding antibodies. By contrast, glycan276-independent CD4bs antibodies, such as VRC01, displace glycan276 upon binding. These results provide a foundation for understanding antibody recognition of glycan276 and suggest its presence may be crucial for priming immunogens seeking to initiate broad CD4bs recognition.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Immune correlates of protection by mRNA-1273 vaccine against SARS-CoV-2 in nonhuman primates

Immune correlates of protection can be used as surrogate endpoints for vaccine efficacy. Here, nonhuman primates (NHPs) received either no vaccine or doses ranging from 0.3 to 100 μg of the mRNA-1273 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine. mRNA-1273 vaccination elicited circulating and mucosal antibody responses in a dose-dependent manner. Viral replication was significantly reduced in bronchoalveolar lavages and nasal swabs after SARS-CoV-2 challenge in vaccinated animals and most strongly correlated with levels of anti–S antibody and neutralizing activity. Lower antibody levels were needed for reduction of viral replication in the lower airway than in the upper airway. Passive transfer of mRNA-1273–induced immunoglobulin G to naïve hamsters was sufficient to mediate protection. Thus, mRNA-1273 vaccine–induced humoral immune responses are a mechanistic correlate of protection against SARS-CoV-2 in NHPs.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Isolation and characterization of cross-neutralizing coronavirus antibodies from COVID-19+ subjects

SARS-CoV-2 is one of three coronaviruses that have crossed the animal-to-human barrier and caused widespread disease in the past two decades. The development of a universal human coronavirus vaccine could prevent future pandemics. We characterize 198 antibodies isolated from four COVID-19+ subjects and identify 14 SARS-CoV-2 neutralizing antibodies. One targets the N-terminal domain (NTD), one recognizes an epitope in S2, and 11 bind the receptor-binding domain (RBD). Three anti-RBD neutralizing antibodies cross-neutralize SARS-CoV-1 by effectively blocking binding of both the SARS-CoV-1 and SARS-CoV-2 RBDs to the ACE2 receptor. Using the K18-hACE transgenic mouse model, we demonstrate that the neutralization potency and antibody epitope specificity regulates the in vivo protective potential of anti-SARS-CoV-2 antibodies. All four cross-neutralizing antibodies neutralize the B.1.351 mutant strain. Thus, our study reveals that epitopes in S2 can serve as blueprints for the design of immunogens capable of eliciting cross-neutralizing coronavirus antibodies.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2020

Antibody evolution immunogens

The present invention relates, in general, to HIV-1 and, in particular, to broadly neutralizing HIV-1 antibodies, and to HIV-1 immunogens and to methods of using such immunogens to induce the production of broadly neutralizing HIV-1 antibodies in a subject (e.g., a human).

Haynes, Barton F.↗