Biology subjects

Piepenbrink, M. S.

Publications and source records attributed to Piepenbrink, M. S..

4 recordsLinked to original sources

bioRxiv2022

Structure and Epitope of a Neutralizing Monoclonal Antibody that Targets the Stem Helix of β Coronaviruses

Monoclonal antibodies (MAbs) that retain neutralizing activity against distinct coronavirus (CoV) lineages and variants of concern (VoC) must be developed to protect against future pandemics. These broadly neutralizing MAbs (BNMAbs) may be used as therapeutics and/or to assist in the rational design of vaccines that induce BNMAbs. 1249A8 is a BNMAb that targets the stem helix (SH) region of CoV spike (S) protein and neutralizes Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) original strain, delta, and omicron VoC, Severe Acute Respiratory Syndrome CoV (SARS-CoV) and Middle East Respiratory Syndrome CoV (MERS-CoV). To understand its mechanism of action, the crystal structure of 1249A8 bound to a MERS-CoV SH peptide was determined at 2.1[A] resolution. BNMAb 1249A8 mimics the SARS-CoV-2 S loop residues 743-749, which interact with the C-terminal end of the SH helix in the S postfusion conformation. The crystal structure shows that BNMAb 1249A8 disrupts SH secondary structure and packing rearrangements required for CoV S to adopt its prefusion conformation that mediates membrane fusion and ultimately infection. The mechanisms regulating BNMAb 1249A8 CoV S specificity are also defined. This study provides novel insights into the neutralization mechanisms of SH-targeting CoV BNMAbs that may inform vaccine development and the design of optimal BNMAb therapeutics.

immunology↗

bioRxiv2022

Potent universal-coronavirus therapeutic activity mediated by direct respiratory administration of a Spike S2 domain-specific human neutralizing monoclonal antibody

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) marks the third novel {beta}-coronavirus to cause significant human mortality in the last two decades. Although vaccines are available, too few have been administered worldwide to keep the virus in check and to prevent mutations leading to immune escape. To determine if antibodies could be identified with universal coronavirus activity, plasma from convalescent subjects was screened for IgG against a stabilized pre-fusion SARS-CoV-2 spike S2 domain, which is highly conserved between human {beta}-coronavirus. From these subjects, several S2-specific human monoclonal antibodies (hmAbs) were developed that neutralized SARS-CoV-2 with recognition of all variants of concern (VoC) tested (Beta, Gamma, Delta, Epsilon, and Omicron). The hmAb 1249A8 emerged as the most potent and broad hmAb, able to recognize all human {beta}-coronavirus and neutralize SARS-CoV and MERS-CoV. 1249A8 demonstrated significant prophylactic activity in K18 hACE2 mice infected with SARS-CoV-2 lineage A and lineage B Beta, and Omicron VoC. 1249A8 delivered as a single 4 mg/kg intranasal (i.n.) dose to hamsters 12 hours following infection with SARS-CoV-2 Delta protected them from weight loss, with therapeutic activity further enhanced when combined with 1213H7, an S1-specific neutralizing hmAb. As little as 2 mg/kg of 1249A8 i.n. dose 12 hours following infection with SARS-CoV Urbani strain, protected hamsters from weight loss and significantly reduced upper and lower respiratory viral burden. These results indicate in vivo cooperativity between S1 and S2 specific neutralizing hmAbs and that potent universal coronavirus neutralizing mAbs with therapeutic potential can be induced in humans and can guide universal coronavirus vaccine development.

immunology↗

bioRxiv2021

Mixed Origins: HIV gp120-specific memory develops from pre-existing memory and naive B cells following vaccination in humans

The most potent and broad HIV envelope (Env)-specific antibodies often when reverted to their inferred germline versions representing the naive B cell receptor, fail to bind Env suggesting that the initial responding B cell population is not exclusively comprised of a naive population, but also a pre-existing cross-reactive antigen-experienced B cell pool that expands following Env exposure. Previously we isolated gp120-reactive monoclonal antibodies (mAbs) from participants in HVTN 105, an HIV vaccine trial. Using deep sequencing VH-lineage tracking we identified several of these mAb lineages in pre-immune peripheral blood. Several of these pre-immune lineages also persisted in the bone marrow, including CD138+ long-lived plasma cell compartment, [~]7 months after the final vaccination. The majority of the pre-immune lineage members included IgM, however IgG and IgA members were also prevalent and exhibited somatic hypermutation. These results suggest that vaccine-induced gp120-specific antibody lineages originate from both naive and cross-reactive memory B cells.

immunology↗

bioRxiv2020

Therapeutic activity of an inhaled potent SARS-CoV-2 neutralizing human monoclonal antibody in hamsters

SARS-CoV-2 infection results in viral burden in the upper and lower respiratory tract, enabling transmission and often leading to substantial lung pathology. Delivering the antiviral treatment directly to the lungs has the potential to improve lung bioavailability and dosing efficiency. As the SARS-CoV-2 Receptor Binding Domain (RBD) of the Spike (S) is increasingly deemed to be a clinically validated target, RBD-specific B cells were isolated from patients following SARS-CoV-2 infection to derive a panel of fully human monoclonal antibodies (hmAbs) that potently neutralize SARS-CoV-2. The most potent hmAb, 1212C2 was derived from an IgM memory B cell, has high affinity for SARS-CoV-2 RBD which enables its direct inhibition of RBD binding to ACE2. The 1212C2 hmAb exhibits in vivo prophylactic and therapeutic activity against SARS-CoV-2 in hamsters when delivered intraperitoneally, achieving a meaningful reduction in upper and lower respiratory viral burden and lung pathology. Furthermore, liquid nebulized inhale treatment of SARS-CoV-2 infected hamsters with as low as 0.6 mg/kg of inhaled dose, corresponding to approximately 0.03 mg/kg of lung deposited dose, mediated a reduction in respiratory viral burden that is below the detection limit, and mitigated lung pathology. The therapeutic efficacy achieved at an exceedingly low-dose of inhaled 1212C2 supports the rationale for local lung delivery and achieving dose-sparing benefits as compared to the conventional parenteral route of administration. Taken together, these results warrant an accelerated clinical development of 1212C2 hmAb formulated and delivered via inhalation for the prevention and treatment of SARS-CoV-2 infection.

immunology↗