Biology subjects

Guest, J. D.

Publications and source records attributed to Guest, J. D..

6 recordsLinked to original sources

bioRxiv2025

Chronic Cervical Midline Contusion in Rats Disrupts Aerobic, Muscular, and Cardiovascular Function

Cardiovascular dysfunction significantly contributes to morbidity and mortality following cervical spinal cord injury (SCI). Unfortunately, only a limited number of preclinical models have been developed for investigating cardiovascular dysfunction following cervical SCI. Furthermore, the broader consequences of cervical SCI on aerobic capacity and muscle endurance during physiological stress testing also remains understudied preclinically. Therefore, in this study we assessed potential deficits across multiple physiological systems in a rat model of cervical SCI using a battery of stress tests. Female Sprague-Dawley rats (n = 20) received either a C8 midline contusion (cSCI) or laminectomy alone as a control (LAM). Exercise stress testing was conducted to evaluate cardiorespiratory fitness and recovery using a metabolic treadmill, or forelimb fitness using the isometric pull task. Orthostatic stress testing and pharmacological stress testing were also performed to more directly challenge the cardiovascular system. Our findings demonstrate a decline in aerobic fitness in cSCI rats, as evidenced by dysregulated excess post-exercise oxygen consumption. cSCI rats also exhibited impaired muscle endurance compared to LAM. During orthostatic stress testing, 70% of cSCI rats experienced an approximately 25 mmHg decrease in systolic blood pressure and 20 mmHg decrease in diastolic blood pressure, in addition to modest but significant decreases in heart rate, myocardial contractility index, stroke volume index, and cardiac output index. During dobutamine infusion, cardiac output index and stroke volume index were significantly reduced following cSCI compared to LAM. Overall, these stress testing results suggest that preclinical cervical SCI in rats can lead to, and therefore model, clinically relevant impairments in cardiopulmonary exercise performance, muscle endurance, and cardiovascular function.

physiology↗

bioRxiv2024

A Comprehensive Engineering Strategy Improves Potency and Manufacturability of a Near Pan-neutralizing Antibody Against HIV

Anti-HIV envelope broadly neutralizing antibodies (bnAbs) are alternatives to conventional antiretrovirals with the potential to prevent and treat infection, reduce latent reservoirs, and/or mediate a functional cure. Clinical trials with "first generation" bnAbs used alone or in combination show promising antiviral effects but also highlight that additional engineering of "enhanced" antibodies will be required for optimal clinical utility, while preserving or enhancing cGMP manufacturing capability. Here we report the engineering of an anti-CD4 binding-site (CD4bs) bnAb, N49P9.3, purified from the plasma of an HIV elite-neutralizer. Through a series of rational modifications we produced a variant that demonstrates: enhanced potency; superior antiviral activity in combination with other bnAbs; low polyreactivity; and longer circulating half-life. Additional engineering for manufacturing produced a final variant, eN49P9, with properties conducive to cGMP production. Overall, these efforts demonstrate the feasibility of developing enhanced anti-CD4bs bnAbs with greatly improved antiviral properties as well as potential translational value.

bioengineering↗

bioRxiv2021

Structural basis for recognition of two HLA-A2-restricted SARS-CoV-2 spike epitopes by public and private T cell receptors

T cells play a vital role in combatting SARS-CoV-2 and in forming long-term memory responses. Whereas extensive structural information is available on neutralizing antibodies against SARS-CoV-2, such information on SARS-CoV-2-specific T cell receptors (TCRs) bound to their peptide-MHC targets is lacking. We determined structures of a public and a private TCR from COVID-19 convalescent patients in complex with HLA-A2 and two SARS-CoV-2 spike protein epitopes (YLQ and RLQ). The structures revealed the basis for selection of particular TRAV and TRBV germline genes by the public but not the private TCR, and for the ability of both TCRs to recognize natural variants of YLQ and RLQ but not homologous epitopes from human seasonal coronaviruses. By elucidating the mechanism for TCR recognition of an immunodominant yet variable epitope (YLQ) and a conserved but less commonly targeted epitope (RLQ), this study can inform prospective efforts to design vaccines to elicit pan-coronavirus immunity.

immunology↗

bioRxiv2021

Structural and energetic profiling of SARS-CoV-2 antibody recognition and the impact of circulating variants

The SARS-CoV-2 pandemic highlights the need for a detailed molecular understanding of protective antibody responses. This is underscored by the emergence and spread of SARS-CoV-2 variants, including B.1.1.7, P1, and B.1.351, some of which appear to be less effectively targeted by current monoclonal antibodies and vaccines. Here we report a high resolution and comprehensive map of antibody recognition of the SARS-CoV-2 spike receptor binding domain (RBD), which is the target of most neutralizing antibodies, using computational structural analysis. With a dataset of nonredundant experimentally determined antibody-RBD structures, we classified antibodies by RBD residue binding determinants using unsupervised clustering. We also identified the energetic and conservation features of epitope residues and assessed the capacity of viral variant mutations to disrupt antibody recognition, revealing sets of antibodies predicted to effectively target recently described viral variants. This detailed structure-based reference of antibody RBD recognition signatures can inform therapeutic and vaccine design strategies.

microbiology↗

bioRxiv2020

CoV3D: A database of high resolution coronavirus protein structures

SARS-CoV-2, the etiologic agent behind COVID-19, exemplifies the general threat to global health posed by coronaviruses. The urgent need for effective vaccines and therapies is leading to a rapid rise in the number of high resolution structures of SARS-CoV-2 proteins that collectively reveal a map of virus vulnerabilities. To assist structure-based design of vaccines and therapeutics against SARS-CoV-2 and other coronaviruses, we have developed CoV3D, a database and resource for coronavirus protein structures, which is updated on a weekly basis. CoV3D provides users with comprehensive sets of structures of coronavirus proteins and their complexes with antibodies, receptors, and small molecules. Integrated molecular viewers allow users to visualize structures of the spike glycoprotein, which is the major target of neutralizing antibodies and vaccine design efforts, as well as sets of spike-antibody complexes, spike sequence variability, and known polymorphisms. In order to aid structure-based design and analysis of the spike glycoprotein, CoV3D permits visualization and download of spike structures with modeled N-glycosylation at known glycan sites, and contains structure-based classification of spike conformations, generated by unsupervised clustering. CoV3D can serve the research community as a centralized reference and resource for spike and other coronavirus protein structures, and is available at: https://cov3d.ibbr.umd.edu.

microbiology↗

bioRxiv2020

Structure-based design of hepatitis C virus E2 glycoprotein improves serum binding and cross-neutralization

An effective vaccine for hepatitis C virus (HCV) is a major unmet need, and it requires an antigen that elicits immune responses to key conserved epitopes. Based on structures of antibodies targeting HCV envelope glycoprotein E2, we designed immunogens to modulate the structure and dynamics of E2 and favor induction of bNAbs in the context of a vaccine. These designs include a point mutation in a key conserved antigenic site to stabilize its conformation, as well as redesigns of an immunogenic region to add a new N-glycosylation site and mask it from antibody binding. Designs were experimentally characterized for binding to a panel of human monoclonal antibodies (HMAbs) and the coreceptor CD81 to confirm preservation of epitope structure and preferred antigenicity profile. Selected E2 designs were tested for immunogenicity in mice, with and without hypervariable region 1, which is an immunogenic region associated with viral escape. One of these designs showed improvement in polyclonal immune serum binding to HCV pseudoparticles and neutralization of isolates associated with antibody resistance. These results indicate that antigen optimization through structure-based design of the envelope glycoproteins is a promising route to an effective vaccine for HCV.

microbiology↗