Biology subjects

Chen, X.

Publications and source records attributed to Chen, X..

At least 973 records · Page 54Linked to original sources

bioRxiv2022

Discovery of E6AP AZUL binding to UBQLN1/2 in cells, phase-separated droplets, and an AlphaFold-NMR integrated structure

The E3 ligase E6AP/UBE3A has a dedicated binding site in the 26S proteasome provided by the RAZUL domain of substrate receptor hRpn10/S5a/PSMD4. Guided by RAZUL sequence similarity, we test and demonstrate here that the E6AP AZUL binds transiently to the UBA of proteasomal shuttle factor UBQLN1/2. Despite a weak binding affinity, E6AP AZUL is recruited to UBQLN2 phase-separated droplets and E6AP interacts with UBQLN1/2 in cells. Steady-state and transfer NOE experiments indicate direct interaction of AZUL with the UBQLN1 UBA domain. Intermolecular contacts identified by NOESY data were combined with AlphaFold2-Multimer predictions to yield an AZUL:UBA model structure. We also identify a concentration-dependent oligomerization domain directly adjacent to UBQLN1/2 UBA (UBA-adjacent, UBAA) that is -helical and allosterically reconfigured by AZUL binding to UBA. These data lead to a model of E6AP recruitment to UBQLN1/2 by AZUL:UBA interaction and provide fundamental information on binding requirements for interactions in droplets and cells.

biophysics↗

bioRxiv2022

Cell circuits between leukemic cells and mesenchymal stem cells block lymphopoiesis by activating lymphotoxin-beta receptor signaling

Acute lymphoblastic and myeloblastic leukemias (ALL and AML) have been known to modify the bone marrow microenvironment and disrupt non-malignant hematopoiesis. However, the molecular mechanisms driving these alterations remain poorly defined. Here we show that leukemic cells turn-off lymphopoiesis and erythropoiesis shortly after colonizing the bone marrow. ALL and AML cells express lymphotoxin-1{beta}2 and activate LT{beta}R signaling in mesenchymal stem cells (MSCs), which turns off IL7 production and prevents non-malignant lymphopoiesis. We show that the DNA damage response pathway and CXCR4 signaling promote lymphotoxin-1{beta}2 expression in leukemic cells. Genetic or pharmacologic disruption of LT{beta}R signaling in MSCs restores lymphopoiesis but not erythropoiesis, reduces leukemic cell growth, and significantly extends the survival of transplant recipients. Similarly, CXCR4 blocking also prevents leukemia-induced IL7 downregulation, and inhibits leukemia growth. These studies demonstrate that acute leukemias exploit physiological mechanisms governing hematopoietic output as a strategy for gaining competitive advantage. One Sentence SummaryLeukemias colonize bone marrow niches and disrupt hematopoiesis. However, the cross-talk between leukemia and niche cells remains poorly understood. We show that leukemia activates LT{beta}R in mesenchymal stem cells which suppresses IL7 production and IL7-dependent lymphopoiesis and accelerates leukemia growth.

immunology↗

bioRxiv2022

Ultrastructure of synaptic connectivity within sub-regions of the SCN revealed by genetically encoded EM tag and SBEM

The suprachiasmatic nucleus (SCN) in the hypothalamus of the vertebrate brain is the central pacemaker regulating circadian rhythmicity throughout the body. The SCN receives photic information through melanopsin-expressing retinal ganglion cells (mRGC) to synchronize the body with environmental light cycles. Determining how these inputs fit into the network of synaptic connections on and between SCN neurons is key to impelling our understanding of the regulation of the circadian clock by light and unraveling the relevant local circuits within the SCN. To map these connections, we used a newly-developed Cre-dependant electron microscopy reporter, APEX2, to label mitochondria of mRGC axons, and serial blockface scanning electron microscopy to resolve the fine structure of mRGC in 3D volumes of the SCN. The maps thus created provide a first draft of the patterns of connectomic organization of SCN in the core and the shell, composed of different neuronal subtypes, and here shown to differ with regard to the patterning of their mRGC input as the shell receives denser mRGCs synaptic inputs compared to the core. This challenges the presently held view that photic information coming directly from the retina is mainly integrated by the core region of the SCN.

neuroscience↗

bioRxiv2022

Comprehensive evaluation of harmonization on functional brain imaging for multisite data-fusion

To embrace big-data neuroimaging, harmonization of site effect in resting-state functional magnetic resonance imaging (R-fMRI) data fusion is a fundamental challenge. Comprehensive evaluation of potentially effective harmonization strategies, particularly with specifically collected data has been rare, especially for R-fMRI metrics. Here, we comprehensively assess harmonization strategies from multiple perspectives, including efficiency, individual identification, test-retest reliability and replicability of group-level statistical results, on widely used R-fMRI metrics across multiple datasets including data obtained from the same participants scanned at several sites. For individual identifiability (i.e., whether the same subject could be identified across R-fMRI data scanned across different sites), we found that, while most methods decreased site effects, the Subsampling Maximum-mean-distance based distribution shift correction Algorithm (SMA) outperformed linear regression models, linear mixed models, ComBat series and invariant conditional variational auto-encoder. Test-retest reliability was better for SMA and adjusted ComBat series than alternatives, while SMA was superior to the latter in replicability, both in terms of Dice coefficient and the scale of brain areas showing sex differences reproducibly observed across datasets. Moreover, we examined test-retest datasets to identify the best target site features to optimize SMA identifiability and test-retest reliability. We noted that both sample size and distribution of the target site matter and introduced a heuristic target site selection formula. In addition to providing practical guidelines, this work can inform continuing improvements and innovations in harmonizing methodologies for big R-fMRI data.

neuroscience↗

bioRxiv2022

Tumoroscope: a probabilistic model for mapping cancer clones in tumor tissues

Spatial and genomic heterogeneity of tumors is the key for cancer progression, treatment, and survival. However, a technology for direct mapping the clones in the tumor tissue based on point mutations is lacking. Here, we propose Tumoroscope, the first probabilistic model that accurately infers cancer clones and their high-resolution localization by integrating pathological images, whole exome sequencing, and spatial transcriptomics data. In contrast to previous methods, Tumoroscope explicitly addresses the problem of deconvoluting the proportions of clones in spatial transcriptomics spots. Applied to a reference prostate cancer dataset and a newly generated breast cancer dataset, Tumoroscope reveals spatial patterns of clone colocalization and mutual exclusion in sub-areas of the tumor tissue. We further infer clone-specific gene expression levels and the most highly expressed genes for each clone. In summary, Tumoroscope enables an integrated study of the spatial, genomic, and phenotypic organization of tumors.

cancer biology↗

bioRxiv2022

The Arabidopsis MCTP member QUIRKY regulates the formation of the STRUBBELIG receptor kinase complex

Intercellular communication plays a central role in organogenesis. Tissue morphogenesis in Arabidopsis thaliana requires signaling mediated by a cell surface complex containing the atypical receptor kinase STRUBBELIG (SUB) and the multiple C2 domains and transmembrane region protein QUIRKY (QKY). QKY is required to stabilize SUB at the plasma membrane. However, it is unclear what the in vivo architecture of the QKY/SUB signaling complex is, how it is controlled, and how it relates to the maintenance of SUB at the cell surface. Using a combination of yeast two-hybrid assays and Forster resonance energy transfer (FRET)/fluorescence lifetime imaging microscopy (FLIM) in epidermal cells of seedling roots we find that QKY promotes the formation of SUB homo-oligomers in vivo, a process that appears to involve an interaction between the extracellular domains of SUB. We also show that QKY and SUB physically interact and form a complex at the cell surface in vivo. In addition, the data show that the N-terminal C2A-B region of QKY interacts with the intracellular domain of SUB. They further reveal that this interaction is essential to maintain SUB levels at the cell surface. Finally, we provide evidence that QKY forms homo-multimers in vivo in a SUB-independent manner. We suggest a model in which the physical interaction of QKY with SUB mediates the oligomerization of SUB and attenuates its internalization, thereby maintaining sufficiently high levels of SUB at the cell surface required for the control of tissue morphogenesis.

plant biology↗

bioRxiv2022

CD73 generated extracellular adenosine promotes resolution of neutrophil-mediated tissue injury and restrains metaplasia in pancreatitis

Background and AimsPancreatitis is currently the leading cause of gastrointestinal hospitalizations in the US. This condition occurs in response to abdominal injury, gallstones, chronic alcohol consumption or, less frequently, the cause remains idiopathic. CD73 is a cell surface ecto-5-nucleotidase that generates extracellular adenosine, which can contribute to resolution of inflammation by binding adenosine receptors on infiltrating immune cells. We hypothesized genetic deletion of CD73 would result in more severe pancreatitis due to decreased generation of extracellular adenosine. MethodsCD73 knockout (CD73-/-) and C57BL/6 (wild type, WT) mice were used to evaluate the progression and response of caerulein-induced acute and chronic pancreatitis. ResultsIn response to caerulein-mediated chronic or acute pancreatitis, WT mice display resolution of pancreatitis at earlier timepoints than CD73-/- mice. Using immunohistochemistry and analysis of single cell RNA-seq (scRNA-seq) data, we determined CD73 localization in chronic pancreatitis is primarily observed in mucin/ductal cell populations and immune cells. In murine pancreata challenged with caerulein to induce acute pancreatitis, we compared CD73-/- to WT mice and observed a significant infiltration of Ly6G+, MPO+, and Granzyme B+ cells in CD73-/- compared to WT pancreata and we quantified a significant increase in acinar-to-ductal metaplasia demonstrating sustained metaplasia and inflammation in CD73-/- mice. Using neutrophil depletion in CD73-/- mice, we show neutrophil depletion significantly reduces metaplasia defined by CK19+ cells per field and significantly reduces acute pancreatitis. ConclusionsThese data identify CD73 agonists as a potential therapeutic strategy for patients with acute and chronic pancreatitis as adenosine generation and activation of adenosine receptors is critical to resolve persistent inflammation in the pancreas. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=140 SRC="FIGDIR/small/508367v1_ufig1.gif" ALT="Figure 1"> View larger version (61K): org.highwire.dtl.DTLVardef@ecae66org.highwire.dtl.DTLVardef@adea9dorg.highwire.dtl.DTLVardef@5f50corg.highwire.dtl.DTLVardef@11b2256_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2022

A Corollary Discharge Circuit in Human Speech

When we vocalize, our brain distinguishes self-generated sounds from external ones. A corollary discharge signal supports this function in animals, however, in humans its exact origin and temporal dynamics remain unknown. We report Electrocorticographic (ECoG) recordings in neurosurgical patients and a novel connectivity approach based on Granger-causality that reveals major neural communications. We find a reproducible source for corollary discharge across multiple speech production paradigms localized to ventral speech motor cortex before speech articulation. The uncovered discharge predicts the degree of auditory cortex suppression during speech, its well-documented consequence. These results reveal the human corollary discharge source and timing with far-reaching implication for speech motor-control as well as auditory hallucinations in human psychosis. Significance statementHow do organisms dissociate self-generated sounds from external ones? A fundamental brain circuit across animals addresses this question by transmitting a blueprint of the motor signal to sensory cortices, referred to as a corollary discharge. However, in humans and non-human primates auditory system, the evidence supporting this circuit has been limited to its direct consequence, auditory suppression. Furthermore, an impaired corollary discharge circuit in humans can lead to auditory hallucinations. While hypothesized to originate in the frontal cortex, direct evidence localizing the source and timing of an auditory corollary discharge is lacking in humans. Leveraging rare human neurosurgical recordings combined with connectivity techniques, we elucidate the exact source and dynamics of the corollary discharge signal in human speech. One-sentence summaryWe reveal the source and timing of a corollary discharge from speech motor cortex onto auditory cortex in human speech.

neuroscience↗

bioRxiv2022

lincRNA RP24-315D19.10 promotes endometrialdecidualization via upregulation of hnRNPA2B1

Sufficient decidualization is necessary to maintain successful pregnancy. The physiological function and underlying molecular mechanisms of intergenic long non-coding RNA (lincRNAs) in this process remain largely unknown. Herein, we identified a lincRNA, RP24-315D19.10, which is highly expressed during mouse decidualization during early pregnancy, by performing RNA-sequencing (RNA-seq) analysis and weighted gene co-expression network analysis (WGCNA). Detailed cell and molecular assays revealed that lincRNA RP24-315D19.10 knockdown blocked decidualization in primary mouse endometrial stromal cells (mESCs), suggesting that RP24-315D19.10 is a promoting factor for decidualization. Mechanistically, cytoplasmic RP24-315D19.10 directly interacted with heterogeneous nuclear ribonucleoprotein A2B1 (hnRNPA2B1) and upregulated its protein level. Moreover, we found that hnRNPA2B1 is involved in the regulation of decidualization through loss- and gain-of-function studies in vitro. Clinically, patients diagnosed with spontaneous miscarriage were found to have lower hnRNPA2B1 levels than healthy individuals, suggesting that RP24-315D19.10-regulated hnRNPA2B1 may participate in the development and progression of early spontaneous abortion. Our study indicates that RP24-315D19.10 enhances endometrial decidualization in a hnRNPA2B1-dependent manner, providing further insights into this physiological process.

molecular biology↗

bioRxiv2022

ApoE4 causes severe COVID-19 outcomes via downregulation of ACE2

The coronavirus disease 2019 (COVID-19) pandemic is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2); host cell entry by this virus relies on the interaction between the receptor-binding domain (RBD) of its spike glycoprotein and the angiotensin-converting enzyme 2 (ACE2) receptor on cell membranes. In addition to serving as a receptor for SARS-CoV-2, ACE2 was originally discovered as a protective factor in the renin-angiotensin system (RAS) that catalyses the degradation of angiotensin II (Ang II) to Ang 1-7, which is involved in multiple organ pathology. Recent genetic and clinical studies reported that ApoE4 expression is associated with increased susceptibility to SARS-CoV-2 infection and the development of severe COVID-19, but the underlying mechanism is currently unclear. In the present study, by using immunofluorescence staining, molecular dynamics simulations, proximity ligation assay (PLA) and coimmunoprecipitation (Co-IP) combined with a biolayer interferometry (BLI) assay, we found that ApoE interacts with both the spike protein and ACE2 but does not show obvious isoform-dependent binding effects. These data suggest that ApoE4 increases SARS-CoV-2 infectivity in a manner that may not depend on differential interactions with the spike protein or ACE2. Importantly, further immunoblotting and immunofluorescence staining results showed that ApoE4 significantly downregulates ACE2 protein expression in vitro and in vivo and subsequently decreases the conversion of Ang II to Ang 1-7, which could worsen tissue lesions; these findings provide a possible explain by which ApoE4 exacerbates COVID-19 disease.

neuroscience↗

bioRxiv2022

Roles of the distinct N-terminal amino acid between H3 and H3.3 in Drosophila male germline stem cell lineage

Adult stem cells undergo asymmetric cell divisions to produce two daughter cells with distinct cell fates: one capable of self-renewal and the other committed for differentiation. Mis-regulation of this delicate balance can lead to cancer and tissue degeneration. During asymmetric division of Drosophila male germline stem cells (GSCs), preexisting (old) and newly synthesized histone H3 are differentially segregated whereas old and new histone variant H3.3 are more equally inherited. However, what underlies these distinct inheritance patterns remains unknown. Here, we report that the N-terminal tails of H3 and H3.3 are critical for their inheritance patterns, as well as GSC maintenance and proper differentiation. H3 and H3.3 differ at the 31st position in their N-termini with Alanine for H3 and Serine for H3.3. By swapping these two amino acids, we generated two mutant histones (i.e., H3A31S and H3.3S31A). Upon expressing them in the early-stage germline, we identified opposing phenotypes: over-population of early-stage germ cells in the H3A31S-expressing testes and significant germ cell loss in testes expressing the H3.3S31A. Asymmetric H3 inheritance is disrupted in the H3A31S-expressing GSCs, due to mis-incorporation of old histones between sister chromatids during DNA replication. Furthermore, H3.3S31A mutation accelerates old histone turn-over in the GSCs. Finally, using a modified Chromatin Immunocleavage assay on early-stage germ cells, we found that H3A31S has an enhanced occupancy at the promoters and transcription starting sites than H3, while H3.3S31A is more enriched at transcriptionally silent intergenic regions compared to H3.3. Overall, these results suggest that the 31st amino acids for both H3 and H3.3 are critical for their proper genomic occupancy and function. Together, our findings indicate a critical role for the different amino acid composition of the N-terminal tails between H3 and H3.3 in an endogenous stem cell lineage, and provide insights into the importance of proper histone inheritance in specifying cell fates and regulating cellular differentiation.

developmental biology↗

bioRxiv2022

Senescent cells develop PDK4-dependent hypercatabolism and form an acidic microenvironment to drive cancer resistance

Cellular senescence is a state of stable growth arrest, usually accompanied by development of the senescence-associated secretory phenotype (SASP). Although senescent cells remain metabolically active, little is known about their metabolic landscape and in vivo pathophysiological implications. Here we show that expression of the pyruvate dehydrogenase (PDH) inhibitory enzyme, pyruvate dehydrogenase kinase 4 (PDK4), is significantly upregulated in human senescent stromal cells. Preferentially expressed upon genotoxicity-induced senescence (GIS), PDK4 is negatively correlated with posttreatment survival of cancer patients. Upon cellular senescence, PDK4 shifts glucose metabolic flux from oxidative phosphorylation to aerobic glycolysis, causing enhanced lactate production and forming an acidic microenvironment. However, distinct from the cancer cell-featured Warburg effect, senescent cells maintain an intensive use of pyruvate through the tricarboxylic acid cycle (TCA), displaying increased respiration and redox activity, indicative of a special form of metabolic reprogramming. Conditioned media from PDK4+ stromal cells change global expression and promote malignancy of recipient cancer cells in vitro and accelerate tumor progression in vivo. Pharmacologically targeting PDK4 restrains the adverse effects of PDK4 in cell-based assays, while promoting tumor regression and extending posttreatment survival in preclinical trials. Together, our study substantiates the hypercatabolic nature of senescent cells, and reveals a metabolic link between senescence-associated acidic microenvironment and age-related pathologies including but not limited to cancer.

cell biology↗

bioRxiv2022

Virome and nrEVEome diversity of Aedes albopictus mosquitoes from La Reunion Island and China

BackgroundAedes albopictus is a public health threat for its worldwide spread and ability to transmit arboviruses. Understanding mechanisms of mosquito immunity can provide new tools to control arbovirus spread. The genomes of Aedes mosquitoes contain hundreads of nonretroviral endogenous viral elements (nrEVEs), which are enriched in piRNA clusters and produce piRNAs, with the potential to target cognate viruses. Recently, one nrEVE was shown to limit cognate viral infection through nrEVE-derived piRNAs. These findings suggest that nrEVEs constitute an archive of past viral infection and that the landscape of viral integrations may be variable across populations depending on their viral exposure. MethodsWe used bioinformatics and molecular approaches to identify known and novel (i.e. absent in the reference genome) viral integrations in the genome of wild collected Aedes albopictus mosquitoes and characterize their virome. ResultsWe showed that the landscape of viral integrations is dynamic with seven novel viral integrations being characterised, but does not correlate with the virome, which includes both viral species known and unknown to infect mosquitoes. However, the small RNA coverage profile of nrEVEs and the viral genomic contigs we identified confimed an interaction among these elements and the piRNA and siRNA pathways in mosquitoes. ConclusionsMosquitoes nrEVEs have been recently descrived as a new form of heritable, sequence-specific mechanism of antiviral immunity. Our results contribute to understanding the dynamic distribution of nrEVEs in the genomes of wild Ae. albopictus and their interaction with mosquito viruses.

genomics↗

bioRxiv2022

ΔNp63 controls stemness and inflammation in the adult epidermis

The p63 transcription factor is critical for epidermis formation in embryonic development, but its role in the adult epidermis is poorly understood. Here we show that acute genetic ablation of {Delta}Np63, the main p63 isoform, in adult epidermis disrupts keratinocyte proliferation and self-maintenance and, unexpectedly, triggers an inflammatory psoriasis-like condition. Mechanistically, single-cell RNA sequencing revealed down-regulation of the cell cycle genes, up-regulation of differentiation markers, and induction of several pro-inflammatory pathways in {Delta}Np63-ablated keratinocytes. Intriguingly, {Delta}Np63-ablated cells disappear three weeks post-ablation, at the expense of the remaining non-ablated cells. This is not associated with active cell death mechanisms, but rather with reduced self-maintenance capacity. Indeed, in vivo wound healing assay, a physiological readout of the epidermal stem cell function, is severely impaired in {Delta}Np63-ablated mice. We found that the Wnt signaling pathway (Wnt10a, Fzd6, Fzd10) and the AP1 factors (JunB, Fos, FosB) are the likely {Delta}Np63 effectors responsible for keratinocyte proliferation/stemness and suppression of differentiation, respectively, while interleukins IL-1a, IL-18, IL-24, and IL-36{gamma} are the likely negative effectors responsible for the suppression of inflammation. These data establish {Delta}Np63 as a critical node that coordinates epidermal homeostasis, stemness, and suppression of inflammation in the adult epidermis, upstream of known regulatory pathways.

cell biology↗

bioRxiv2022

L-Fucose is a candidate monosaccharide neuromodulator and mitigates Alzheimer's synaptic deficits

We identified a novel signaling function of L-fucose, a structurally unique monosaccharide. We showed that L-fucose enhanced excitatory neurotransmission and long-term potentiation (LTP) in Schaffer-collateral-CA1 synapses. L-fucose was released by neurons in an activity- and store-dependent manner, and induced rapid signaling changes to enhance presynaptic release. Such effects required L-fucose metabolism through the salvage pathway driven by fucokinase (FUK). Thus, L-fucose could be the first described monosaccharide neuromodulator affecting a metabolic-signaling mechanism. Human Alzheimers disease (AD) and 5xFAD mouse brains showed signs of fucose hypometabolism with impaired L-fucose signaling. Such abnormalities could be corrected by exogenous L-fucose, exemplified by rectification of LTPdeficits in 5xFAD hippocampus. Dietary L-fucose supplement, which increased cerebral free L-fucose levels and upregulated FUK to drive the salvage pathway, mitigated synaptic and behavioral deficits of 5xFAD mice. Our data reveals a therapeutic potential of oral L-fucose for AD, which is safe and easy to comply with.

neuroscience↗

bioRxiv2022

SIC50: Determination of IC50 by an optimized Sobel operator and a vision transformer

As a measure of cytotoxic potency, half-maximal inhibitory concentration (IC50) is the concentration at which a drug exerts half of its maximal inhibitory effect against target cells. It can be determined by various methods that require applying additional reagents or lysing the cells. Here, we describe a label-free Sobel-edge-based method, which we name SIC50, for the evaluation of IC50. SIC50 classifies pre-processed phase-contrast images with a state-of-art vision transformer and allows for the continuous assessment of IC50 in a faster and more cost-efficient manner. We have validated this method using four drugs and 1536-well plates, as well as built a first-of-its-kind web application. We anticipate this method will assist in the high-throughput screening of chemical libraries (e.g., small molecule drugs, siRNA, and microRNA and drug discovery.

bioengineering↗

bioRxiv2022

Systematic characterization of chromodomain proteins revealsan H3K9me1/2 reader regulating aging in C. elegans

The chromatin organization modifier domain (chromodomain) is an evolutionally conserved motif across eukaryotic species. The chromodomain mainly functions as a histone methyl-lysine reader to modulate gene expression, chromatin spatial conformation and genome stability. Mutations or aberrant expression of chromodomain proteins can result in cancer and other human diseases. Here, we systematically tagged chromodomain proteins with green fluorescent protein (GFP) using CRISPR/Cas9 technology in C. elegans. By combining ChIP-seq analysis and imaging, we delineated a comprehensive expression and functional map of chromodomain proteins. We then conducted a candidate-based RNAi screening and identified factors that regulate the expression and subcellular localization of the chromodomain proteins. Specifically, we revealed a new H3K9me1/2 reader, CEC-5, both by in vitro biochemistry and in vivo ChIP assays. MET-2, an H3K9me1/2 writer, is required for CEC-5 association with heterochromatin. Both MET-2 and CEC-5 are required for the normal lifespan of C. elegans. Furthermore, a forward genetic screening identified a conserved Arginine124 of CEC-5s chromodomain, which was essential for CEC-5s association with chromatin and life span regulation. Thus, our work will serve as a reference to explore chromodomain functions and regulation in C. elegans and allow potential applications in aging-related human diseases.

molecular biology↗

bioRxiv2022

A single-administration therapeutic interfering particle reduces SARS-CoV-2 viral shedding and pathogenesis in hamsters

The high transmissibility of SARS-CoV-2 is a primary driver of the COVID-19 pandemic. While existing interventions prevent severe disease, they exhibit mixed efficacy in preventing transmission, presumably due to their limited antiviral effects in the respiratory mucosa, whereas interventions targeting the sites of viral replication might more effectively limit respiratory virus transmission. Recently, intranasally administered RNA-based therapeutic interfering particles (TIPs) were reported to suppress SARS-CoV-2 replication, exhibit a high barrier to resistance, and prevent serious disease in hamsters. Since TIPs intrinsically target the tissues with the highest viral replication burden (i.e., respiratory tissues for SARS-CoV-2), we tested the potential of TIP intervention to reduce SARS-CoV-2 shedding. Here, we report that a single, post-exposure TIP dose lowers SARS-CoV-2 nasal shedding and at 5 days post-infection infectious virus shed is below detection limits in 4 out of 5 infected animals. Furthermore, TIPs reduce shedding of Delta variant or WA-1 from infected to uninfected hamsters. Co-housed contact animals exposed to infected, TIP-treated, animals exhibited significantly lower viral loads, reduced inflammatory cytokines, no severe lung pathology, and shortened shedding duration compared to animals co-housed with untreated infected animals. TIPs may represent an effective countermeasure to limit SARS-CoV-2 transmission. SignificanceCOVID-19 vaccines are exceptionally effective in preventing severe disease and death, but they have mixed efficacy in preventing virus transmission, consistent with established literature that parenteral vaccines for other viruses fail to prevent mucosal virus shedding or transmission. Likewise, small-molecule antivirals, while effective in reducing viral-disease pathogenesis, also appear to have inconsistent efficacy in preventing respiratory virus transmission including for SARS-CoV-2. Recently, we reported the discovery of a single-administration antiviral Therapeutic Interfering Particle (TIP) against SARS-CoV-2 that prevents severe disease in hamsters and exhibits a high genetic barrier to the evolution of resistance. Here, we report that TIP intervention also reduces SARS-CoV-2 transmission between hamsters.

microbiology↗