David M. Belnap

University of Utah

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Alasdair C. Steven

National Institutes of Health

Naiqian Cheng

National Institute of Arthritis and Musculoskeletal and Skin Diseases

James M. Hogle

Harvard University

David J. Filman

Harvard University

Davide Corti

VIR Biotechnology (United States)

Gyorgy Snell

VIR Biotechnology (United States)

Amalio Telenti

VIR Biotechnology (United States)

Saveez Saffarian

University of Utah

Benjamin Preece

University of Utah

Fabrizia Zatta

Vir Biotechnology (Switzerland)

Cooperative Institutions

University of Utah

VIR Biotechnology (United States)

Vir Biotechnology (Switzerland)

National Institutes of Health

European Foundation for the Study of Chronic Liver Failure

Harvard University

Brigham Young University

National Institute of Arthritis and Musculoskeletal and Skin Diseases

Stanford University

University of Washington

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Detection of Bacteriophages: Electron Microscopy and Visualisation

Springer eBooks (2021)

David M. Belnap

Negative stain

10.1007/978-3-319-40598-8_18-2

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Citations (0)

Common conventions for interchange and archiving of three-dimensional electron microscopy information in structural biology

Journal of Structural Biology (2005)

J. Bernard Heymann Mónica Chagoyen David M. Belnap

Presentation (obstetrics)

Representation

Data Exchange

Data set

10.1016/j.jsb.2005.06.001

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Citations (67)

Encapsulating Nanoemulsions Inside eLiposomes for Ultrasonic Drug Delivery

Langmuir (2012)

Marjan Javadi William G. Pitt David M. Belnap Naakaii H. Tsosie Jonathan M. Hartley

An eLiposome is a liposome encapsulating an emulsion nanodroplet and can be used for drug delivery. For example, therapeutic agents are encapsulated inside the eLiposomes, and the application of ultrasound can cause the emulsion droplet to change from liquid to gas, thus increasing the volume inside the vesicle and causing rupture and the release of the drug. In this research, two different methods were used to prepare eLiposomes. In the first method, emulsion droplets were made of perfluorohexane or perfluoropentane and stabilized with 1,2-dipalmitoyl-sn-glycero-3-phosphate. A layer of 1,2-dimyristoyl-sn-glycero-3-phosphocholine was dried in a round-bottomed flask. Then the emulsion suspension was added to the flask. As the suspension hydrated the phospholipids, they formed liposomes around the emulsions. In the second method, emulsions and liposomes were made separately, and then they were mixed using ultrasound. The advantage of this second method compared to the previous one is that eLiposomes can be made with fewer restrictions because of incompatible combinations of surfactants. Dynamic light scattering and transmission electron microscopy were used to measure the size of the emulsions, liposomes, and eLiposomes. The size of eLiposomes is appropriate for extravasation into tumors with malformed capillary beds. We hypothesize that ultrasound breaks open these eLiposomes. Both types of eLiposomes were constructed with folate attached via a poly(ethylene glycol) tether to induce endocytosis of the eLiposome. The latter eLiposomes were successfully used to deliver calcein as a model drug to HeLa cells.

Calcein

Suspension

10.1021/la303464v

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Citations (77)

Contents

Journal of Hepatology (2023)

Patrizia Burra Frank Tacke Vlad Ratziu S Zeuzem Bruno Sangro

10.1016/s0168-8278(23)05114-0

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Structure and function of ATP-dependent protease Clp(Chaperonin-linked-protease)

Seibutsu Butsuri (2000)

Taisuke Ishikawa Fabienne Beuron David M. Belnap Martin Kessel Sue Wickner

Chaperonin

10.2142/biophys.40.s33_3

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Enhanced Yield and Gentle Purification of HIV for Cryo-Electron Tomography Analysis of Virion Maturation

bioRxiv (Cold Spring Harbor Laboratory) (2024)

Benjamin Preece Wiley Peppel Rodrigo Gallegos Gillian Yassasi Gabe Clinger

Abstract HIV is a lentivirus characterized by the formation of its mature core. Visualization and structural examination of HIV requires purification of virions to high concentrations. The yield and integrity of these virions are crucial for ensuring a uniform representation of all viral particles in subsequent analyses. In this study, we present a method for purification of HIV virions which minimizes forces applied to virions while maximizing the efficiency of collection. This method allows us to capture between 1,000 and 5,000 HIV virions released from individual HEK293 cells after transfection with the NL4.3 HIV backbone, a 10 fold advantage over other methods. We utilized this approach to investigate HIV core formation from several constructs: pNL4-3(RT:D 185 A&D 186 A) with an inactive reverse transcriptase, NL4.3(IN: V 165 A&R 166 A) with a type-II integrase mutation, and NL4.3(Ѱ: Δ(105-278)&Δ(301-332)) featuring an edited Ѱ packaging signal. Notably, virions from NL4.3(Ѱ: Δ(105-278)&Δ(301-332)) displayed a mixed population, comprising immature virions, empty cores, and cores with detectable internal density. Conversely, virions derived from NL4.3(IN: V 165 A&R 166 A) exhibited a type II integrase mutant phenotype characterized by empty cores and RNP density localized around the cores, consistent with previous studies. In contrast, virions released from pNL4-3(RT:D 185 A&D 186 A) displayed mature cores containing detectable RNP density. We suggest that the purification methods developed in this study can significantly facilitate the characterization of enveloped viruses.

HEK 293 cells

Core protein

10.1101/2024.12.12.628087

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Low-Resolution Density Maps from Atomic Models: How Stepping “Back” Can Be a Step “Forward”

Journal of Structural Biology (1999)

David M. Belnap Abhinav Kumar Jon T. Folk Thomas J. Smith Timothy S. Baker

10.1006/jsbi.1999.4093

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Citations (29)

Minimal system for assembly of SARS-CoV-2 virus like particles

bioRxiv (Cold Spring Harbor Laboratory) (2020)

Heather Swann Abhimanyu Sharma Benjamin Preece Abby Peterson Crystal Eldridge

Abstract SARS-CoV-2 virus is the causative agent of COVID-19. Here we demonstrate that non-infectious SARS-CoV-2 virus like particles (VLPs) can be assembled by co-expressing the viral proteins S, M and E in mammalian cells. The assembled SARS-CoV-2 VLPs possess S protein spikes on particle exterior, making them ideal for vaccine development. The particles range in shape from spherical to elongated with a characteristic size of 129 ± 32 nm. We further show that SARS-CoV-2 VLPs dried in ambient conditions can retain their structural integrity upon repeated scans with Atomic Force Microscopy up to a peak force of 1 nN.

Virus-like particle

Particle (ecology)

Sars virus

10.1101/2020.06.01.128058

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Citations (6)

The engineered monoclonal antibody tobevibart enhances HBsAg capture by Fc receptor positive cells leading to activation of HBV-specific T cells

medRxiv (Cold Spring Harbor Laboratory) (2025)

Lucia Vincenzetti Rachel Wong Roberta Marzi Barbara Guarino Erin Stefanutti

Background & Aims: Immune targeting is likely required for functional cure of chronic hepatitis B (CHB). Tobevibart, a human monoclonal antibody against hepatitis B virus (HBV) surface antigen (HBsAg), neutralizes HBV and hepatitis delta virus (HDV). This study aimed to characterize effects of the engineered GAALIE Fc of tobevibart on HBV immune responses. Methods: We studied tobevibart and its equivalent HBC34*-GAALIE in vitro using electron microscopy, FcgR reporter cells, and primary human or mouse immune cells to assess HBsAg binding, dendritic cell (DC) activation, and T cell stimulation. Tobevibart-mediated binding of HBsAg to immune cells was evaluated also in a phase 1 clinical trial in patients with CHB. Results: The GAALIE Fc of tobevibart mediated gain of function in FcgR signaling in immune complexes (ICs) with HBsAg compared to wild-type (WT) Fc and increased binding of HBsAg to neutrophils and monocytes in vitro. Similarly, dosing of 300 mg tobevibart in patients with CHB mediated binding of HBsAg to these cells in vivo, concomitant with reducing HBsAg in circulation. In vitro, ICs of HBC34*-GAALIE and HBsAg activated human DCs significantly more than HBC34*-WT. These DCs presented antigen and stimulated HBsAg-specific human T cells. Similarly, ICs of HBC34*-GAALIE and HBsAg activated DCs from mice transgenic for human FcgRs and stimulated CD4+ T cells from immunized animals more than ICs with HBC34*- WT. Conclusions: We demonstrate that tobevibart combines the advantages of potent neutralization of HBV and HDV, FcgR-mediated reduction of HBsAg, and Fc-dependent enhancement of T cell responses. Tobevibart is currently under clinical investigation alone or in combination with other agents to treat patients with chronic hepatitis delta and to induce functional cure of patients with CHB.

10.1101/2025.01.13.25320453

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Membrane proteins significantly restrict exosome mobility

Biochemical and Biophysical Research Communications (2018)

Mikhail Skliar Vasiliy S. Chernyshev David M. Belnap German V. Sergey Samer M. Al-Hakami

Exosome

Cell membrane

10.1016/j.bbrc.2018.05.107

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Citations (68)