Biology subjects

Brown, R.

Publications and source records attributed to Brown, R..

At least 37 records · Page 2Linked to original sources

bioRxiv2024

Novel phylogenomic inference and 'Out of Asia' biogeography of cobras, coral snakes, and their allies

Estimation of evolutionary relationships among lineages that rapidly diversified can be challenging, and, in such instances, inaccurate or unresolved phylogenetic estimates can lead to erroneous conclusions regarding historical geographical ranges of lineages. One example underscoring this issue has been the historical challenge posed by untangling the biogeographic origin of elapoid snakes, which includes numerous dangerously venomous species as well as species not known to be dangerous to humans. The worldwide distribution of this lineage makes it an ideal group for testing hypotheses related to historical faunal exchanges among the many continents and other landmasses occupied by contemporary elapoid species. We developed a novel suite of genomic resources, included worldwide sampling, and inferred a robust estimate of evolutionary relationships, which we leveraged to quantitatively estimate geographical range evolution through the deep-time history of this remarkable radiation. Our phylogenetic and biogeographical estimates of historical ranges definitively reject a lingering former Out of Africa hypothesis and support an Out of Asia scenario involving multiple faunal exchanges between Asia, Africa, Australasia, the Americas, and Europe.

evolutionary biology↗

bioRxiv2024

Edinger-Westphal ghrelin receptor signalling regulates binge alcohol consumption in a sex specific manner

BackgroundRates of risky drinking are continuing to rise, particularly in women, yet sex as a biological variable has been largely ignored. An emerging yet understudied potential component of this circuitry is the central projecting Edinger-Westphal (EWcp), which is made up of two prominent, but distinct cell populations expressing either an array of neuropeptides (including cocaine and amphetamine regulated transcript; CART) or vGlut2 (glutamatergic). MethodsHere, we use a combination of approaches including genetic, molecular biology, behavioural testing, and electrophysiology to understand how the EWcp contributes to alcohol consumption in female versus male mice. ResultsChemogenetic inhibition of EWcpCART cells reduced binge drinking specifically in female, but not male mice. Further, inhibition of EWcpCART cells prevented ghrelin induced drinking, and viral-mediated ghrelin receptor (Ghsr) knockdown in the EWcp reduced binge drinking in female, but not male mice. RNAscope revealed Ghsr expression across peptidergic (marked by CART) and glutamatergic populations in the EWcp, with neurons from female mice more sensitive to bath application of ghrelin than male mice. Targeted knockdown of Ghsr from distinct EWcp populations revealed GHSR signalling on peptidergic, but not glutamatergic cells mediate binge drinking in female mice. Finally, both a GHSR inverse agonist and antagonist delivered directly within the EWcp reduced binge drinking in female mice. ConclusionsThese findings suggest the EWcp is a region mediating excessive alcohol bingeing through GHSR actions on peptidergic cells (CART-expressing) in female mice and expand our understanding of the neural mechanism(s) underpinning how the ghrelin system mediates alcohol consumption.

neuroscience↗

bioRxiv2023

METTL3 alters capping enzyme expression and its activity on ribosomal proteins

The 5 cap, catalyzed by RNA guanylyltransferase and 5-phosphatase (RNGTT), is a vital mRNA modification for the functionality of mRNAs. mRNA capping occurs in the nucleus for the maturation of the functional mRNA and in the cytoplasm for fine-tuning gene expression. Given the fundamental importance of RNGTT in mRNA maturation and expression there is a need to further investigate the regulation of RNGTT. N6-methyladenosine (m6A) is one of the most abundant RNA modifications involved in the regulation of protein translation, mRNA stability, splicing, and export. We sought to investigate whether m6A could regulate the expression and activity of RNGTT. A motif for the m6A writer methyltransferase 3 (METTL3) in the 3UTR of RNGTT mRNA was identified. Knockdown of METTL3 resulted in destabilizing RNGTT mRNA, and reduced protein expression. Sequencing of capped mRNAs identified an underrepresentation of ribosomal protein mRNA overlapping with 5 terminal oligopyrimidine (TOP) mRNAs and genes are dysregulated when cytoplasmic capping is inhibited. Pathway analysis identified disruptions in the mTOR and p70S6K pathways. A reduction in RPS6 mRNA capping, protein expression, and phosphorylation was detected with METTL3 knockdown.

molecular biology↗

bioRxiv2023

The circulating immune cell landscape stratifies metastatic burden in breast cancer patients

Advanced breast cancers show varying degrees of metastasis; however, reliable biomarkers of metastatic disease progression remain unknown. In circulation, immune cells are the first line of defence against tumour cells. Herein, using >109,591 peripheral blood mononuclear cells from healthy individuals and breast cancer patients, we tested whether molecular traits of the circulating immune cells, probed with single-cell transcriptomics, can be used to segregate metastatic profiles. Our analyses revealed significant compositional and transcriptional differences in PBMCs of patients with restricted or high metastatic burden versus healthy subjects. The abundance of T cell and monocyte subtypes segregated cancer patients from healthy individuals, while memory and unconventional T cells were enriched in low metastatic burden disease. The cell communication axes were also found to be tightly associated with the extent of metastatic burden. Additionally, we identified a PBMC-derived metastatic gene signature capable of discerning metastatic condition from a healthy state. Our study provides unique molecular insights into the peripheral immune system operating in metastatic breast cancer, revealing potential new biomarkers of the extent of the metastatic state. Tracking such immune traits associated with metastatic spread could complement existing diagnostic tools.

cancer biology↗

bioRxiv2023

cMYC-mediated immune repression is reversed by inhibition of H3K9/H3K27 methylation maintenance

Aberrant cMYC activity is a key driver of cancer, involved in several hallmark processes. Alongside the canonical hallmark of proliferation, cMYC represses immune signalling in a cell-intrinsic manner. The histone methyltransferases EZH2 and G9a interact with cMYC to modulate gene expression, including repression of immune genes via H3K27 and H3K9 histone methylation. Analyses of 565 cell lines derived from solid cancers demonstrated that greater cMYC-G9a/EZH2-mediated repression correlates with lower immune gene scores in a cell-intrinsic manner (innate, Type I and Type II IFN response), an effect most evident in MYC-amplified cell lines. In ovarian high-grade serous carcinoma (HGSC) cell lines and an in vivo murine model of HGSC, HKMTi-1-005, an inhibitor of H3K27/H3K9 methylation maintenance, relieved cMYC-G9a/EZH2 repression whilst inducing an immune response. A 7-gene immune signature (7ISG), related to viral mimicry signalling, is at the core of the HGSC immune response to HKMTi-1-005. In MYC-amplified HGSC patients, a low 7ISG score was associated with poor survival. Additionally, MYC-amplified cell lines were significantly more sensitive to HKMTi-1-005, whilst a low 7ISG score was associated with greater HKMTi-1-005 sensitivity, effects that were independent of canonical cMYC transcriptional activation. Examining the effects of HKMTi-1-005 treatment in a MYC-deregulated lung adenocarcinoma (LuAd) revealed induction of an immune response in vitro and prolonged survival in vivo. This suggests that inhibition of H3K27/H3K9 methylation maintenance will have efficacy in cMYC-deregulated tumours with low 7ISG scores, via disruption of cMYC-mediated repression of cell autonomous immune signalling and induction of an anti-tumour immune response. Statement of significanceOver 70% of cancers are cMYC-deregulated. We show that inhibition of H3K27/H3K9 methylation maintenance relieves cMYC-dependent immune repression and prolongs survival of animal tumour models, suggesting a novel approach to treating cMYC-deregulated tumours.

cancer biology↗

bioRxiv2023

Volumetrically tracking retinal and choroidal structural changes in central serous chorioretinopathy

Central serous chorioretinopathy (CSCR) leads to accumulation of subretinal fluid and retinal thickness change, which can be readily detected in clinics using optical coherence tomography (OCT). However, current quantification methods usually require sophisticated processing such as retinal layer segmentations, and volumetric visualization of structural changes is generally challenging, which can hinder fast and accurate assessment of disease progression and/or treatment efficacy. In this study, we developed an algorithm that can register the OCT scans acquired from different visits without requiring prior layer segmentation and calculated the three-dimensional (3-D) structural change maps for patients with CSCR. Our results demonstrate that this tool can be useful in monitoring the progression of CSCR and revealing the resolution of pathologies following treatment automatically with minimal pre-processing.

bioengineering↗

bioRxiv2023

Maintenance of pig brain function under extracorporeal pulsatile circulatory control (EPCC)

Selective vascular access to the brain is desirable in metabolic tracer, pharmacological and other studies aimed to characterize neural properties in isolation from somatic influences from chest, abdomen or limbs. However, current methods for artificial control of cerebral circulation can abolish pulsatility-dependent vascular signaling or neural network phenomena such as the electrocorticogram even when preserving individual neuronal activity. Thus, we set out to mechanically render cerebral hemodynamics fully regulable to replicate or modify native pig brain perfusion. To this end, blood flow to the head was surgically separated from the systemic circulation and full extracorporeal pulsatile circulatory control (EPCC) delivered via a modified aorta or brachiocephalic artery. This control relied on a computerized algorithm that maintained, for several hours, blood pressure, flow and pulsatility at near-native values individually measured before EPCC. Continuous electrocorticography and brain depth electrode recordings were used to evaluate brain activity relative to the standard offered by awake human electrocorticography. Under EPCC, this activity remained unaltered or minimally perturbed compared to the native circulation state, as did cerebral oxygenation, pressure, temperature and microscopic structure. Thus, our approach enables the study of neural activity and its circulatory manipulation in independence of most of the rest of the organism.

neuroscience↗

bioRxiv2022

Stress-Induced Mucosal Layer Disruption Drives Gut Dysbiosis and Depressive-like Behaviors

Depression is a prevalent psychological condition with limited treatment options. While its etiology is multifactorial, both chronic stress and changes in the microbiome are associated with disease pathology. In depression, stress is known to induce microbiome dysbiosis, defined here as a change in microbial composition associated with a pathological condition. This state of dysbiosis is then known to feedback on depressive symptoms. While studies have demonstrated that targeted restoration of the microbiome can alleviate depressive-like symptoms in mice, translating these findings to human patients has proven challenging due to the complexity of the human microbiome. As such, there is an urgent need to identify factors upstream of microbial dysbiosis. Here we investigate the role of mucin 13 as an upstream mediator of microbiome composition changes. Using a model of chronic stress, we show that the mucosal protein, mucin 13, is selectively reduced after psychological stress exposure. We further demonstrate that the reduction of Muc13 is mediated by the Hnf4 transcription factor family. Finally, we determine that deleting Muc13 is sufficient to drive microbiome shifts and despair behaviors. These findings shed light on the mechanisms behind stress-induced microbial changes and reveal a regulator of mucin 13 expression. SummaryIn this paper, authors identified a pathway by which stress induces microbiome shifts. They found that psychological stress selectively alters a key mucosal protein, mucin 13, which in turn modifies the microbial niche to induce changes in bacterial composition.

microbiology↗

bioRxiv2022

P1 bacteriophage-enabled delivery of CRISPR-Cas9 antimicrobial activity against Shigella flexneri

The discovery of clustered, regularly interspaced, short palindromic repeats (CRISPR) and the Cas9 RNA-guided nuclease provides unprecedented opportunities to selectively kill specific populations or species of bacteria. However, the use of CRISPR-Cas9 to clear bacterial infections in vivo is hampered by the inefficient delivery of cas9 genetic constructs into bacterial cells. Here, we use a broad-host-range P1-derived phagemid to deliver the CRISPR-Cas9 chromosomal-targeting system into Escherichia coli and the dysentery-causing Shigella flexneri to achieve DNA sequence-specific killing of targeted bacterial cells. We show that genetic modification of the helper P1 phage DNA packaging site (pac) significantly enhances the purity of packaged phagemid and improves the Cas9-mediated killing of S. flexneri cells. We further demonstrate that P1 phage particles can deliver chromosomal-targeting cas9 phagemids into S. flexneri in vivo using a zebrafish larvae infection model, where it significantly reduces the bacterial load and promotes host survival. Our study highlights the potential of combining a P1 bacteriophage-based delivery with the CRISPR chromosomal-targeting system to achieve DNA sequence-specific cell lethality and efficient clearance of bacterial infection.

microbiology↗

bioRxiv2022

Dual inhibition of SHP2 and autophagy suppresses NF1-associated Malignant Peripheral Nerve Sheath Tumors

Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive sarcomas and the primary cause of mortality in patients with neurofibromatosis type 1 (NF1). MPNSTs develop within pre-existing benign plexiform neurofibromas (PNs). PNs are driven solely by biallelic NF1 loss eliciting RAS pathway activation and respond favorably to MEK inhibitor therapy. Our analysis of genetically engineered and orthotopic patient-derived xenograft MPNST indicates that MEK inhibition has poor anti-tumor efficacy. By contrast, upstream inhibition of RAS through the protein-tyrosine phosphatase SHP2 reduced downstream signaling and suppressed NF1 MPNST growth, although resistance eventually emerged. To investigate possible mechanisms of acquired resistance, kinomic analyses of resistant tumors was performed, and data analysis identified enrichment of activated autophagy pathway protein kinases. Combining pharmacological blockade of autophagy and SHP2 inhibition resulted in durable responses in NF1 MPNSTs in both genetic and orthotopic xenograft mouse models. Our studies can be rapidly translated into a clinical trial to evaluate SHP2 inhibition in conjunction with autophagy inhibitors as a novel treatment approach for NF1 MPNSTs. Statement of significanceCurrently, no effective therapies exist for MPNST. We demonstrate intrinsic MPNST resistance to MEKi monotherapy and identify SHP2 inhibition as an actionable vulnerability upstream of RAS. Furthermore, anti-tumor effects are extended and enhanced by dual exposure to autophagy pathway inhibition. Validation of these results as the most effective therapy to date in multiple genetically engineered models and in orthotopic patient-derived xenografts justify a clinical trial to evaluate SHP2i in conjunction with autophagy inhibitors as a novel treatment approach for NF1 MPNSTs.

cancer biology↗

bioRxiv2022

An ACAT inhibitor regulates SARS-CoV-2 replication and antiviral T cell activity

The severity of disease following infection with SARS-CoV-2 is determined by viral replication kinetics and host immunity, with early T cell responses and/or suppression of viraemia driving a favourable outcome. Recent studies have uncovered a role for cholesterol metabolism in the SARS-CoV-2 life cycle and in T cell function. Here we show that blockade of the enzyme Acyl-CoA:cholesterol acyltransferase (ACAT) with Avasimibe inhibits SARS-CoV-2 entry and fusion independent of transmembrane protease serine 2 expression in multiple cell types. We also demonstrate a role for ACAT in regulating SARS-CoV-2 RNA replication in primary bronchial epithelial cells. Furthermore, Avasimibe boosts the expansion of functional SARS-CoV-2-specific T cells from the blood of patients sampled in the acute phase of infection. Thus, re-purposing of available ACAT inhibitors provides a compelling therapeutic strategy for the treatment of COVID-19 to achieve both antiviral and immunomodulatory effects.

immunology↗

bioRxiv2022

Acyl ghrelin attenuates neurochemical and motor deficits in the 6OHDA model of Parkinsons disease

The feeding-related hormone, acyl-ghrelin, protects dopamine neurons in murine 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-based models of experimental Parkinsons disease (PD). However, the potential protective effect of acyl-ghrelin on substantia nigra pars compacta (SNpc) dopaminergic neurones and consequent behavioural correlates in the more widely used 6-hydroxydopamine (6-OHDA) rat medial forebrain bundle (MFB) lesion model of PD are unknown. To address this question, acyl-ghrelin levels were raised directly by mini-pump infusion for 7-days prior to unilateral injection of 6-OHDA into the MFB with assessment of amphetamine-induced rotations on days 27 and 35, and immunohistochemical analysis of dopaminergic neurone survival. While acyl-ghrelin treatment was insufficient to elevate food intake or body weight, it attenuated amphetamine-induced circling behaviour and SNpc dopamine neurone loss induced by 6-OHDA. These data support the notion that elevating circulating acyl-ghrelin may be a valuable approach to slow or impair progression of neurone loss in PD. HighlightsO_LIAcyl-ghrelin attenuates SNpc dopamine cell loss in rat 6-OHDA-lesion model of PD C_LIO_LIAcyl-ghrelin attenuates motor deficits in rat 6-OHDA-lesion model of PD C_LI

neuroscience↗

bioRxiv2022

Applied phenomics and genomics for improving barley yellow dwarf resistance in winter wheat

Barley yellow dwarf (BYD) is one of the major viral diseases of cereals. Phenotyping BYD in wheat is extremely challenging due to similarities to other biotic and abiotic stresses. Breeding for resistance is additionally challenging as the wheat primary germplasm pool lacks genetic resistance, with most of the few resistance genes named to date originating from a wild relative species. The objectives of this study were to, i) evaluate the use of high-throughput phenotyping (HTP) from unmanned aerial systems to improve BYD assessment and selection, ii) identify genomic regions associated with BYD resistance, and iii) evaluate genomic prediction models ability to predict BYD resistance. Up to 107 wheat lines were phenotyped during each of five field seasons under both insecticide treated and untreated plots. Across all seasons, BYD severity was lower with the insecticide treatment and plant height (PTHTM) and grain yield (GY) showed increased values relative to untreated entries. Only 9.2% of the lines were positive for the presence of the translocated segment carrying resistance gene Bdv2 on chromosome 7DL. Despite the low frequency, this region was identified through association mapping. Furthermore, we mapped a potentially novel genomic region for resistance on chromosome 5AS. Given the variable heritability of the trait (0.211 - 0.806), we obtained relatively good predictive ability for BYD severity ranging between 0.06 - 0.26. Including Bdv2 on the predictive model had a large effect for predicting BYD but almost no effect for PTHTM and GY. This study was the first attempt to characterize BYD using field-HTP and apply GS to predict the disease severity. These methods have the potential to improve BYD characterization and identifying new sources of resistance will be crucial for delivering BYD resistant germplasm.

genetics↗

bioRxiv2021

Kismet/CHD7/CHD8 affects gut biomechanics, the gut microbiome, and gut-brain axis in Drosophila melanogaster

The gut-brain axis may contribute to the pathophysiology of neurodevelopmental disorders, yet it is often unclear how risk genes associated with these disorders affect gut physiology in a manner that could impact microbial colonization. We addressed this question using Drosophila melanogaster with a null mutation in kismet, the ortholog of chromodomain helicase DNA-binding protein (CHD) family members CHD7 and CHD8. In humans, CHD7 and CHD8 are risk genes for neurodevelopmental disorders with co-occurring gastrointestinal symptoms. We found kismet mutant flies have a significant increase in gastrointestinal transit time, indicating functional homology of kismet with CHD7/CHD8 in vertebrates. To measure gut tissue mechanics, we used a high-precision force transducer and length controller, capable of measuring forces to micro-Newton precision, which revealed significant changes in the mechanics of kismet mutant guts, in terms of elasticity, strain stiffening, and tensile strength. Using 16S rRNA metagenomic sequencing, we also found kismet mutants have reduced diversity of gut microbiota at every taxonomic level and an increase in pathogenic taxa. To investigate the connection between the gut microbiome and behavior, we depleted gut microbiota in kismet mutant and control flies and measured courtship behavior. Depletion of gut microbiota rescued courtship defects of kismet mutant flies, indicating a connection between gut microbiota and behavior. In striking contrast, depletion of gut microbiome in the control strain reduced courtship activity. This result demonstrated that antibiotic treatment can have differential impacts on behavior that may depend on the status of microbial dysbiosis in the gut prior to depletion. We propose that Kismet influences multiple gastrointestinal phenotypes that contribute to the gut-brain axis to influence behavior. Based on our results, we also suggest that gut tissue mechanics should be considered as an element in the gut-brain communication loop, both influenced by and potentially influencing the gut microbiome and neuronal development.

developmental biology↗

bioRxiv2021

An intranasally administrated SARS-CoV-2 beta variant subunit booster vaccine prevents beta variant viral replication in rhesus macaques

Emerging of SARS-CoV-2 variants and waning of vaccine/infection-induced immunity poses threats to curbing the COVID-19 pandemic. An effective, safe, and convenient booster vaccine will be needed. We hypothesized that a variant-modified mucosal booster vaccine might induce local immunity to prevent SARS-CoV-2 infection at the port of entry. The beta-variant is hardest to cross-neutralize. Herein we assessed the protective efficacy of an intranasal booster composed of beta variant-spike protein S1 with IL-15 and TLR agonists in previously immunized macaques. The macaques were first vaccinated with Wuhan strain S1 with the same adjuvant. One year later, negligibly detectable SARS-CoV-2-specific antibody remained. Nevertheless, the booster induced vigorous humoral immunity including serum- and bronchoalveolar lavage (BAL)-IgG, secretory nasal- and BAL-IgA, and neutralizing antibody against the original strain and/or beta variant. Beta-variant S1-specifc CD4+ and CD8+ T cell responses were also elicited in PBMC and BAL. Following SARS-CoV-2 beta variant challenge, the vaccinated group demonstrated significant protection against viral replication in the upper and lower respiratory tracts, with almost full protection in the nasal cavity. The fact that one intranasal beta-variant booster administrated one year after the first vaccination provoked protective immunity against beta variant infections may inform future SARS-CoV-2 booster design and administration timing.

immunology↗

bioRxiv2021

Optimization of Non-Coding Regions Improves Protective Efficacy of an mRNA SARS-CoV-2 Vaccine in Nonhuman Primates

The CVnCoV (CureVac) mRNA vaccine for SARS-CoV-2 has recently been evaluated in a phase 2b/3 efficacy trial in humans. CV2CoV is a second-generation mRNA vaccine with optimized non-coding regions and enhanced antigen expression. Here we report a head-to-head study of the immunogenicity and protective efficacy of CVnCoV and CV2CoV in nonhuman primates. We immunized 18 cynomolgus macaques with two doses of 12 ug of lipid nanoparticle formulated CVnCoV, CV2CoV, or sham (N=6/group). CV2CoV induced substantially higher binding and neutralizing antibodies, memory B cell responses, and T cell responses as compared with CVnCoV. CV2CoV also induced more potent neutralizing antibody responses against SARS-CoV-2 variants, including B.1.351 (beta), B.1.617.2 (delta), and C.37 (lambda). While CVnCoV provided partial protection against SARS-CoV-2 challenge, CV2CoV afforded robust protection with markedly lower viral loads in the upper and lower respiratory tract. Antibody responses correlated with protective efficacy. These data demonstrate that optimization of non-coding regions can greatly improve the immunogenicity and protective efficacy of an mRNA SARS-CoV-2 vaccine in nonhuman primates.

immunology↗

bioRxiv2021

Combined single cell proteomics and transcriptomics reveals discrete human tendon cells populations persist in vitro and on fibrous scaffolds

Chronic tendinopathy represents a growing burden to healthcare services in an active and ageing global population. The ability to identify, isolate and interrogate, in vitro, key pathogenic and reparative tendon cell populations is essential to developing precision therapies and implantable materials. Human hamstring tendon cells were cultured for 8 days on either tissue culture plastic or aligned electrospun fibres made of polydioxanone (absorbable polymer). Combined single cell surface proteomics and unbiased single cell transcriptomics (CITE-Seq) revealed six discrete cell clusters, four of which shared key gene expression determinants with ex vivo human cell clusters. These were PTX3_PAPPA, POST_SCX, DCN_LUM and ITGA7_NES cell clusters. Surface proteomics found that PTX3_PAPPA cells were CD10+CD26+CD54+. ITGA7_NES cells were CD146+, and POSTN_SCX cells were CD90+CD95+CD10+. Three clusters preferentially survived and proliferated on the aligned electrospun fibres; DCN_LUM, POSTN_SCX, and PTX3_PAPPA. They maintained high expression of tendon matrix associated genes, including COL1A1, COL1A2, COL3A1, ELN, FBLN1, and up-regulated genesets enriched for TNF-{gamma} signalling via NF{kappa}B, IFN-{gamma} signalling and IL-6/ STAT3 signalling. When cells were pre-selected based on surface protein markers, a similar up-regulation of pro-inflammatory signalling pathways was observed, particularly in PTX3 gene expressing CD10+CD26+CD54+ cells, with increased expression of genes associated with TNF- signalling and IFN-{gamma} signalling. Discrete human tendon cell sub populations persist in vitro culture and can be recognised by specific gene and surface protein signatures. Aligned PDO fibres promote the survival of three clusters, including pro-inflammatory PTX3 expressing CD10+CD26+CD54+ cells found in chronic tendon disease.

cell biology↗

bioRxiv2021

A modular protein subunit vaccine candidate produced in yeast confers protection against SARS-CoV-2 in non-human primates

Vaccines against SARS-CoV-2 have been distributed at massive scale in developed countries, and have been effective at preventing COVID-19. Access to vaccines is limited, however, in low- and middle-income countries (LMICs) due to insufficient supply, high costs, and cold storage requirements. New vaccines that can be produced in existing manufacturing facilities in LMICs, can be manufactured at low cost, and use widely available, proven, safe adjuvants like alum, would improve global immunity against SARS-CoV-2. One such protein subunit vaccine is produced by the Serum Institute of India Pvt. Ltd. and is currently in clinical testing. Two protein components, the SARS-CoV-2 receptor binding domain (RBD) and hepatitis B surface antigen virus-like particles (VLPs), are each produced in yeast, which would enable a low-cost, high-volume manufacturing process. Here, we describe the design and preclinical testing of the RBD-VLP vaccine in cynomolgus macaques. We observed titers of neutralizing antibodies (>104) above the range of protection for other licensed vaccines in non-human primates. Interestingly, addition of a second adjuvant (CpG1018) appeared to improve the cellular response while reducing the humoral response. We challenged animals with SARS-CoV-2, and observed a ~3.4 and ~2.9 log10 reduction in median viral loads in bronchoalveolar lavage and nasal mucosa, respectively, compared to sham controls. These results inform the design and formulation of current clinical COVID-19 vaccine candidates like the one described here, and future designs of RBD-based vaccines against variants of SARS-CoV-2 or other betacoronaviruses.

immunology↗