Biology subjects

Harvey, D. J.

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

4 recordsLinked to original sources

bioRxiv2024

Structural and Functional Glycosylation of the Abdala COVID-19 Vaccine

Abdala is a COVID-19 vaccine produced in Pichia pastoris and is based on the receptor-binding domain (RBD) of the SARS-CoV-2 spike. Abdala is currently approved for use in multiple countries with clinical trials confirming its safety and efficacy in preventing severe illness and death. Although P. pastoris is used as an expression system for protein-based vaccines, yeast glycosylation remains largely uncharacterised across immunogens. Here, we characterise N-glycan structures and their site of attachment on Abdala and show how yeast-specific glycosylation decreases binding to the ACE2 receptor and a receptor-binding motif (RBM) targeting antibody compared to the equivalent mammalian-derived RBD. Reduced receptor and antibody binding is attributed to changes in conformational dynamics resulting from N-glycosylation. These data highlight the critical importance of glycosylation in vaccine design and demonstrate how individual glycans can influence host interactions and immune recognition via protein structural dynamics.

biochemistry↗

bioRxiv2024

The alpha4 nicotinic acetylcholine receptor is necessary for the initiation of organophosphate-induced neuronal hyperexcitability

Acute intoxication with organophosphorus (OP) cholinesterase inhibitors can produce seizures that rapidly progress to life-threatening status epilepticus. Significant research effort has been invested investigating the involvement of muscarinic acetylcholine receptors (mAChRs) in OP-induced seizure activity. In contrast, there has been far less effort focused on nicotinic AChRs (nAChRs) in this context. Here, we address this data gap using a combination of in vitro and in vivo models. Pharmacological antagonism and genetic deletion of 4, but not 7, nAChR subunits prevented or significantly attenuated OP-induced electrical spike activity in acute hippocampal slices and seizure activity in mice, indicating that 4 nAChR activation is necessary for neuronal hyperexcitability triggered by acute OP exposures. These findings not only suggest that therapeutic strategies for inhibiting the 4 nAChR subunit warrant further investigation as prophylactic and acute treatments for acute OP-induced seizures, but also provide mechanistic insight into the role of the nicotinic cholinergic system in seizure generation.

pharmacology and toxicology↗

bioRxiv2020

Networks of HIV-1 envelope glycans maintain antibody epitopes in the face of glycan additions and deletions

Numerous broadly neutralizing antibodies (bnAbs) have been identified that target the glycans of the HIV-1 envelope spike. Neutralization breadth is notable given that glycan processing can be substantially influenced by the presence or absence of neighboring glycans. Here, using a stabilized recombinant envelope trimer, we investigate the degree to which mutations in the glycan network surrounding an epitope impact the fine glycan processing of antibody targets. Using cryo-electron microscopy and site-specific glycan analysis, we reveal the hierarchy of importance of glycans in the formation of the 2G12 bnAb epitope, and show that the epitope is only subtly impacted by variations in the glycan network. In contrast, we show that the PG9 and PG16 glycan-based epitopes at the trimer apex are dependent on the presence of the highly conserved surrounding glycans. Glycan networks underpin the conservation of bnAb epitopes and are an important parameter in immunogen design.

immunology↗

bioRxiv2019

Endothelial-derived exosomes demonstrate a link between endothelial innate inflammation and brain dysfunction and injury in aging

We test the hypothesis that endothelial cells take on an inflammatory phenotype in functionally intact human subjects with radiographic evidence of white matter injury. Markers within all three complement effector pathways and regulatory proteins were quantified from endothelial-derived exosomes (EDE) of subjects (age 70-82) with (n=11) and without (n=16) evidence of white matter hyperintensity on MRI. Group differences and associations with systemic markers of immune activation (IL6, ICAM1), cognition and neuroimaging were calculated via regression modelling.\n\nEDE complement factors within the alternative and classical pathways were found to be higher and regulatory proteins lower in subjects with WMH. EDE levels of several factors demonstrated significant associations with cognitive slowing and systolic blood pressure. The inhibitor of the membrane attack complex, CD46, showed a significant positive association with cerebral grey matter volume. Systemic inflammatory markers, IL6 and ICAM1, were positively associated with EDE levels of several factors.\n\nThese findings provide the first in vivo evidence of the association of endothelial cell inflammation with white matter injury, cognition, and brain degeneration in functionally normal older individuals, and form the basis for future biomarker development in early or preclinical stages of vascular cognitive impairment and dementia.

neuroscience↗