Biology subjects

Miller, M. S.

Publications and source records attributed to Miller, M. S..

17 recordsLinked to original sources

bioRxiv2026

Innate Defense Mechanisms Against Nosema ceranae in Hygienic Honey Bee (Apis mellifera) Colonies

The honey bee colony (Apis mellifera) acts as a superorganism, with a dual immune system that operates at the individual and social level. However, the linkages between immune mechanisms across the two levels remain poorly understood, despite the relevance for developing effective breeding strategies to improve honey bee disease resistance. Hygienic behavior involving the removal of unhealthy brood is a key component of honey bee social immunity and is highly effective at limiting parasites and pathogens in the colony. While this form of hygienic behavior can reduce brood diseases, parasites infecting adult bees primarily, such as Nosema ceranae, are not directly impacted by the behavior. However, when using the Unhealthy Brood Odor (UBeeO) assay to quantify hygienic behavior performance, hygienic colonies have been shown to maintain lower Nosema spp. loads over time and overall compared to non-hygienic colonies. To investigate the mechanisms driving reduced Nosema spp. in hygienic colonies, we conducted a series of field and lab experiments to test the innate immune performance of individual bees. We evaluated several factors across hygienic and non-hygienic bees including (1) differences in N. ceranae infection levels, (2) survival probability, (3) Vitellogenin and Hymenoptaecin gene expression, and (4) amount of N. ceranae inoculant consumed. We found that hygienic bees consumed less of the inoculant, exhibited upregulated Vitellogenin gene expression at peak N. ceranae infection, showed a positive relationship between Hymenoptaecin gene expression and N. ceranae infection levels, and had greater survivability when infected with N. ceranae, compared to non-hygienic bees. Here, we present new findings that link colony hygienic behavior performance to individual-level resistance and tolerance mechanisms in response to N. ceranae, suggesting broader implications for the success of selective breeding programs targeting hygienic traits.

immunology↗

bioRxiv2025

Senataxin is required for optimal class switch recombination to the immunoglobulin A isotype

Senataxin (SETX) is an RNA/DNA helicase that plays a pivotal role in transcription, R-loop resolution, and the DNA damage response (DDR). Dysfunction of SETX, however, has been implicated in neurodegenerative diseases, including amyotrophic lateral sclerosis and ataxia with oculomotor apraxia type 2. Importantly, both R-loop resolution and the DDR are essential for class switch recombination (CSR) in B cells, a critical step in generating antibody diversity. Here we demonstrate that ex vivo polyclonal stimulation of SETX+/+ and SETX-/- mouse splenocytes results in equivalent amounts of IgM- and IgG-secreting B cells but significantly fewer IgA-producing B cells in SETX-/- mice. Additionally, SETX-/- mice generate significantly reduced antigen specific IgA titers following infection with influenza A virus. Sequencing of the IgA-secreting B cell repertoire revealed reduced clonal diversity in SETX-/- mice. SETX-/- mice also had increased R-loop formation within the IgA locus. Collectively, these data highlight an important role for SETX in mediating CSR to IgA. As such, a further understanding of SETXs role in the immune response is important for expanding our knowledge of both the general immunobiology relating to CSR as well as the immunological phenotypes associated with neurodegenerative diseases associate with mutations in SETX. One sentence summaryA deficiency in senataxin results in impaired class switching to IgA in vitro with decreased IgA response to infection and IgA repertoire diversity in vivo.

immunology↗

bioRxiv2025

Phosphate and acidosis cause fiber-type specific changes to cellular and molecular contractile mechanics at 37°C in skeletal muscle from older adults

Intracellular accumulation of hydrogen ions (H+) and inorganic phosphate (Pi) have temperature-dependent effects on single fiber contractile function between 10-30{degrees}C. In vivo, human skeletal muscle temperatures range between 35-38{degrees}C, and although contractile function is highly dependent on temperature, the effects of fatigue-inducing [H+] and [Pi] on contractile mechanics at 37{degrees}C is unknown. Using sinusoidal analysis, the independent and combined effects of these metabolites on cellular and molecular contractile function were determined at 37{degrees}C in slow-contracting myosin heavy chain (MHC) I and fast-contracting MHC IIA fibers from vastus lateralis muscle of 13 older adults (8 females), under four conditions: maximal calcium activation ("control"; 5 mM Pi, pH 7.0), high Pi (30 mM), low pH (6.2), and fatigue (30 mM Pi and pH 6.2). Specific tension (force/cross-sectional area, mN/mm2) in both fiber types was reduced only under fatigue conditions (20-26%). MHC I fibers had slower cross-bridge kinetics with fewer or less stiff strongly-bound myosin-actin cross-bridges in high Pi, low pH, and fatigue. In contrast, fatigued MHC IIA fibers had faster cross-bridge kinetics with increased myofilament and/or cross-bridge viscosity. Single fiber oscillatory work was reduced in both fiber types when Pi or pH alone was altered. However, fatigue conditions returned oscillatory work values toward control through alterations to cross-bridge kinetics in MHC I fibers and changes to work absorption and production processes in MHC IIA fibers. These findings quantify fiber-type specific mechanical and kinetic mechanisms of fatigue in human skeletal muscle at 37{degrees}C, thus advancing our understanding of metabolite-based muscle fatigue in vivo. KEY POINTS SUMMARYO_LIWorking skeletal muscle increases intracellular concentrations of hydrogen ion and inorganic phosphate, leading to fatigue, or loss of force-generating capacity C_LIO_LITemperature plays a well-established role in the muscle response to hydrogen ion and/or inorganic phosphate accumulation, but has not previously been studied at human body temperature (37{degrees}C) C_LIO_LIAt 37{degrees}C, reduced force generation only occurs when high phosphate and hydrogen ions are combined, not when changed individually C_LIO_LIIn slow-contracting fibers, fatigue slowed myosin-actin cross-bridge kinetics and reduced the number or stiffness of strongly-bound cross-bridges. In fast-contracting fibers, fatigue increased myosin-actin cross-bridge kinetics and increased myofilament viscosity. C_LIO_LIThe distinct responses by fiber type to fatigue provides new insight into its mechanisms and advances our understanding of the whole muscle and body responses to fatigue C_LI Abstract Figure O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=125 SRC="FIGDIR/small/672942v1_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@e4ece3org.highwire.dtl.DTLVardef@17c62eforg.highwire.dtl.DTLVardef@1434e30org.highwire.dtl.DTLVardef@1c2446c_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗

bioRxiv2025

Slow- and fast-contracting skeletal muscle fibers have more similar cellular and molecular contractile function at 37°C than at 25°C in older adults

As human skeletal muscle cellular and molecular contractile properties are temperature-sensitive, the ability to perform experiments at body temperature ([~]37{degrees}C) may lead to a better understanding of their in vivo responses and potentially their effects upon whole-muscle and whole-body performance. We quantified molecular (myosin-actin cross-bridge mechanics and kinetics) and cellular (specific tension; force divided by cross-sectional area) function in slow-contracting myosin heavy chain (MHC) I and fast-contracting MHC IIA fibers from older adults (n=13, 8 female) at 37{degrees}C and compared these to results at 25{degrees}C. MHC I fibers were more temperature-sensitive than MHC IIA fibers, showing greater increases in cross-bridge kinetics (MHC I: 4.9-8.7x; IIA: 4x) and number or stiffness of strongly-bound cross-bridges (MHC I: 86%; IIA: 34%), leading to increased specific tension in MHC I (19%), with no change in MHC IIA fibers. The expected relationship between fiber force and size (cross-sectional area, CSA) was stronger at 37{degrees}C in both fiber types, explaining 80-82% of the variance compared to 51-52% at 25{degrees}C. Specific tension was unchanged with size at 37{degrees}C in both fiber types, showing that force increases proportionally with CSA, which may be due to the increased number or stiffness of strongly-bound cross-bridges at this temperature. At 25{degrees}C, specific tension decreased with size in agreement with previous experiments. Overall, MHC I and IIA fibers at body temperature (37{degrees}C) became more analogous, including similar specific tension and closer cross-bridge kinetics, and force production was more strongly correlated with fiber size compared to a non-physiological temperature. Abstract Figure O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=103 SRC="FIGDIR/small/670366v1_ufig1.gif" ALT="Figure 1"> View larger version (20K): org.highwire.dtl.DTLVardef@70fe6aorg.highwire.dtl.DTLVardef@4ef5e4org.highwire.dtl.DTLVardef@1f1551forg.highwire.dtl.DTLVardef@10ba6d1_HPS_FORMAT_FIGEXP M_FIG C_FIG KEY POINTS SUMMARYO_LIAlthough skeletal muscle function is highly sensitive to temperature, human single fiber studies have only been conducted at [≤]30{degrees}C. C_LIO_LISmall-amplitude sinusoidal perturbations were utilized to elucidate mechanisms of single fiber force production at human physiological temperature (37{degrees}C). C_LIO_LIWe found that functional differences in slow-contracting myosin heavy chain (MHC I) and fast-contracting MHC IIA fibers observed at 25{degrees}C were less apparent at 37{degrees}C, as force, crossbridge kinetics, and strongly-bound crossbridges increased more in MHC I fibers than MHC IIA fibers at 37 vs. 25{degrees}C. C_LIO_LIThese results indicate that, given the different sensitivity of each fiber type to changes in temperature, functional assessments of muscle should be conducted at 37{degrees}C to better translate to vivo conditions. C_LI

physiology↗

bioRxiv2024

Acute Viral Infection Accelerates Neurodegeneration in a Mouse Model of ALS

While several viral infections have been associated with amyotrophic lateral sclerosis (ALS), the mechanism(s) through which they promote disease has remained almost entirely elusive. This study investigated the impact of common, acute viral infections prior to disease onset on ALS progression in the SOD1G93A mouse model. A single sublethal infection prior to onset of ALS clinical signs was associated with markedly accelerated ALS disease progression characterized by rapid loss of hindlimb function. Prior infection resulted in gliosis in the lumbar spine and upregulation of transcriptional pathways involved in inflammatory responses, metabolic dysregulation, and muscular dysfunction. Therapeutic suppression of gliosis with an anti-inflammatory small molecule, or administration of a direct-acting antiviral, was associated with significantly improved ALS clinical signs, akin to what was observed in uninfected animals. This study provides causal and mechanistic evidence that the immune response elicited by acute viral infections may be an important etiological factor that alters ALS disease trajectory, and provides insight into novel therapeutic and preventative strategies for ALS. One Sentence SummaryAcute viral infection with influenza A virus and SARS-CoV-2 accelerates the progression of ALS in SOD1G93A mice.

immunology↗

bioRxiv2024

Respiratory mucosal administration of DNA aptamer nanomaterials protects against antigenically diverse SARS-CoV-2 variants

The ongoing COVID-19 pandemic has highlighted the need for innovative therapeutic strategies to combat rapidly evolving pathogens that challenge the efficacy of traditional vaccines and monoclonal antibody treatments. Here, we explored the potential of TMSA52, a previously described homotrimeric DNA aptamer as a universal prophylactic and therapeutic agent against SARS-CoV-2. TMSA52 demonstrates exceptional binding affinities and broad neutralization against diverse SARS-CoV-2 variant spike proteins that are further enhanced through multimerization onto lamellar iridium nanoplates. Respiratory mucosal delivery of TMSA52 nanomaterials was well-tolerated. Surprisingly, TMSA52 offered potent protection from infection with ancestral SARS-CoV-2 on-par with monoclonal antibodies, and superior protection against antigenically distant SARS-CoV-2 variants. These findings establish DNA aptamers as a promising, cost-effective, and scalable alternative to traditional monoclonal antibody therapies. This study underscores the potential of aptamer-based platforms as a next-generation strategy to enhance global pandemic preparedness and expand our arsenal of infectious disease countermeasures.

immunology↗

bioRxiv2024

Distinctive retinal peri-arteriolar versus peri-venular amyloid plaque distribution correlates with the cognitive performance

IntroductionThe vascular contribution to Alzheimers disease (AD) is tightly connected to cognitive performance across the AD continuum. We topographically describe retinal perivascular amyloid plaque (AP) burden in subjects with normal or impaired cognition. MethodsUsing scanning laser ophthalmoscopy, we quantified retinal peri-arteriolar and peri-venular curcumin-positive APs in the first, secondary and tertiary branches in twenty-eight subjects. Perivascular AP burden among cognitive states was correlated with neuroimaging and cognitive measures. ResultsPeri-arteriolar exceeded peri-venular AP count (p<0.0001). Secondary branch AP count was significantly higher in cognitively impaired (p<0.01). Secondary small and tertiary peri-venular AP count strongly correlated with clinical dementia rating, hippocampal volumes, and white matter hyperintensity count. DiscussionOur topographic analysis indicates greater retinal amyloid accumulation in the retinal peri-arteriolar regions overall, and distal peri-venular regions in cognitively impaired individuals. Larger longitudinal studies are warranted to understand the temporal-spatial relationship between vascular dysfunction and perivascular amyloid deposition in AD. HighlightsO_LIRetinal peri-arteriolar region exhibits more amyloid compared with peri-venular regions. C_LIO_LISecondary retinal vascular branches have significantly higher perivascular amyloid burden in subjects with impaired cognition, consistent across sexes. C_LIO_LICognitively impaired individuals have significantly greater retinal peri-venular amyloid deposits in the distal small branches, that correlate with CDR and hippocampal volumes. C_LI

pathology↗

bioRxiv2023

Targeting the MR1-MAIT Cell Axis Improves Vaccine Efficacy and Affords Protection against Viral Pathogens

Mucosa-associated invariant T (MAIT) cells are MR1-restricted, innate-like T lymphocytes with tremendous antibacterial and immunomodulatory functions. MAIT cells also sense and respond to viral infections in an MR1-independent fashion. However, whether they can be directly targeted in immunization strategies against viral pathogens is unknown. We addressed this question in multiple wild-type and genetically altered but clinically relevant mouse strains using several vaccine platforms against influenza viruses, poxviruses and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We demonstrate that 5-(2-oxopropylideneamino)-6-D-ribitylaminouracil (5-OP-RU), a riboflavin-based MR1 ligand of bacterial origin, can synergize with viral vaccines to expand MAIT cells in multiple tissues, reprogram them towards a pro-inflammatory MAIT1 phenotype, license them to bolster mainstream virus-specific CD8+ T cell responses, and potentiate heterosubtypic antiviral protection. Repeated 5-OP-RU administration did not render MAIT cells anergic, thus allowing for its inclusion in prime-boost immunization protocols. Mechanistically, tissue MAIT cell accumulation was due to their robust proliferation, as opposed to altered migratory behavior, and required viral vaccine replication competency, Toll-like receptor 3 (TLR3) and cell-autonomous type I interferon receptor signaling. Furthermore, the observed phenomenon was manifest in young and old female and male mice, and could also be recapitulated in a human cell culture system in which peripheral blood mononuclear cells were exposed to replicating virions and 5-OP-RU. In conclusion, although viruses and virus-based vaccines are devoid of the riboflavin biosynthesis machinery that supplies MR1 ligands, targeting MR1 enhances the efficacy of vaccine-elicited antiviral immunity. We propose 5-OP-RU as a non-classic but potent and versatile vaccine adjuvant against respiratory viruses.

immunology↗

bioRxiv2022

Comprehensive analysis of the human ESCRT-III-MIT domain interactome reveals new cofactors for cytokinetic abscission

The 12 related human ESCRT-III proteins form filaments that constrict membranes and mediate fission, including during cytokinetic abscission. The C-terminal tails of polymerized ESCRT-III subunits also bind proteins that contain Microtubule-Interacting and Trafficking (MIT) domains. MIT domains can interact with ESCRT-III tails in many different ways to create a complex binding code that recruits essential cofactors to sites of ESCRT activity. Here, we have comprehensively and quantitatively mapped the interactions between all known ESCRT-III tails and 19 pure recombinant human MIT domains. We measured 228 pairwise interactions, quantified 58 positive interactions, and discovered 16 previously unreported interactions. We also report the crystal structure of the SPASTIN MIT domain in complex with the IST1 C-terminal tail. Three MIT enzymes were studied in detail and shown to: 1) localize to cytokinetic midbody membrane bridges through interactions with their specific ESCRT-III binding partners (SPASTIN-IST1, KATNA1-CHMP3, and CAPN7-IST1), 2) function in abscission (SPASTIN, KATNA1, and CAPN7), and 3) function in the "NoCut" abscission checkpoint (SPASTIN and CAPN7). Our studies define the human MIT-ESCRT-III interactome, identify new factors and activities required for cytokinetic abscission and its regulation, and provide a platform for analyzing ESCRT-III and MIT cofactor interactions in all ESCRT-mediated processes.

biochemistry↗

bioRxiv2021

Broadly-neutralizing antibodies that bind to the influenza hemagglutinin stalk domain enhance the effectiveness of neuraminidase inhibitors via Fc-mediated effector functions

The conserved hemagglutinin stalk domain is an attractive target for broadly effective antibody-based therapeutics and next generation universal influenza vaccines. Protection provided by hemagglutinin stalk binding antibodies is principally mediated through activation of immune effector cells. Titers of stalk-binding antibodies are highly variable on an individual level, and tend to increase with age as a result of increasing exposures to influenza virus. In our study, we show that stalk-binding antibodies cooperate with neuraminidase inhibitors to protect against influenza virus infection in an Fc-dependent manner. These data suggest that the effectiveness of neuraminidase inhibitors is likely influenced by an individuals titers of stalk-binding antibodies, and that neuraminidase inhibitors may enhance the effectiveness of future stalk-binding monoclonal antibody-based treatments.

immunology↗

bioRxiv2021

Single-dose respiratory mucosal delivery of next-generation viral-vectored COVID-19 vaccine provides robust protection against both ancestral and variant strains of SARS-CoV-2

The emerging SARS-CoV-2 variants of concern (VOC) increasingly threaten the effectiveness of current first-generation COVID-19 vaccines that are administered intramuscularly and are designed to only target the spike protein. There is thus a pressing need to develop next-generation vaccine strategies to provide more broad and long-lasting protection. By using adenoviral vectors (Ad) of human and chimpanzee origin, we developed Ad-vectored trivalent COVID-19 vaccines expressing Spike-1, Nucleocapsid and RdRp antigens and evaluated them following single-dose intramuscular or intranasal immunization in murine models. We show that respiratory mucosal immunization, particularly with chimpanzee Ad-vectored vaccine, is superior to intramuscular immunization in induction of the three-arm immunity, consisting of local and systemic antibody responses, mucosal tissue-resident memory T cells, and mucosal trained innate immunity. We further show that single-dose intranasal immunization provides robust protection against not only the ancestral strain of SARS-CoV-2, but also two emerging VOC, B.1.1.7 and B.1.351. Our findings indicate that single-dose respiratory mucosal delivery of an Ad-vectored multivalent vaccine represents an effective next-generation COVID-19 vaccine strategy against current and future VOC. This strategy has great potential to be used not only to boost first-generation vaccine-induced immunity but also to expand the breadth of protective T cell immunity at the respiratory mucosa.

immunology↗

bioRxiv2021

Gut microbiota-based vaccination engages innate immunity to improve blood glucose control in obese mice

Obesity and diabetes increase circulating levels of microbial components derived from the gut microbiota. Individual bacterial factors (i.e., postbiotics) can have opposing effects on metabolic inflammation and blood glucose control. We tested the net effect of gut bacterial extracts on blood glucose using a microbiota-based vaccination strategy in mice. Male and female mice had improved insulin sensitivity and blood glucose control five weeks after a single subcutaneous injection of a specific dose of a bacterial extract obtained from the luminal contents of the proximal gut. Injection of mice with proximal gut extracts from germ-free mice revealed that bacteria were required for a microbiota-based vaccination to improve blood glucose control. Vaccination of Nod1-/-, Nod2-/-, and Ripk2-/- mice showed that each of these innate immune proteins was required for bacterial extract injection to improve blood glucose control. A microbiota-based vaccination promoted a proximal gut immunoglobulin-G (IgG) response directed against bacterial extract antigens, where subcutaneous injection of mice with the luminal contents of the ileum elicited a bacterial extract-specific IgG response that is compartmentalized to the ileum of vaccinated mice. A microbiota-based vaccination was associated with an altered the microbiota composition in the ileum and colon of mice. Lean mice required a single injection of proximal gut bacterial extracts, but high fat diet (HFD)-fed, obese mice required prime-boost bacterial extract injections for improvements in blood glucose control. These data show that, upon subversion of the gut barrier, vaccination with proximal gut bacterial extracts engages innate immunity to promote long-lasting improvements in blood glucose control in a dose-dependent manner.

physiology↗

bioRxiv2021

IgA Potentiates NETosis in Response to Viral Infection

IgA is the second most abundant antibody present in circulation and is enriched at mucosal surfaces. As such, IgA plays a key role in protection against a variety of mucosal pathogens, including viruses. In addition to neutralizing viruses directly, IgA can also stimulate Fc-dependent effector functions via engagement of Fc alpha receptors (FcRI) expressed on the surface of certain immune effector cells. Neutrophils are the most abundant leukocyte, express FcRI, and are often the first to respond to sites of injury and infection. Here, we describe a novel function for IgA:virus immune complexes (ICs) during viral infections. We show that IgA:virus ICs potentiate NETosis - the programmed cell death pathway through which neutrophils release neutrophil extracellular traps (NETs). Mechanistically, IgA:virus ICs potentiated a suicidal NETosis pathway via engagement of FcRI on neutrophils through a toll-like receptor (TLR)-independent, NADPH oxidase complex-dependent pathway. NETs also were capable of trapping and inactivating viruses, consistent with an antiviral function.

immunology↗

bioRxiv2020

Potentiation of Long-Acting β2-Agonist and Glucocorticoid Responses in Human Airway Epithelial Cells by Modulation of Intracellular cAMP

IntroductionOver 300 million people in the world live with asthma, resulting in 500,000 annual global deaths with future increases expected. It is estimated that around 50-80% of asthma exacerbations are due to viral infections. Currently, a combination of long-acting beta agonists (LABA) for bronchodilation and glucocorticoids (GCS) to control lung inflammation represent the dominant strategy for the management of asthma, however it is still sub-optimal in 35-50% of moderate-severe asthmatics resulting in persistent lung inflammation, impairment of lung function, and risk of mortality. Mechanistically, LABA/GCS combination therapy results in synergistic efficacy mediated by intracellular cyclic adenosine monophosphate (cAMP). HypothesisIncreasing intracellular cAMP during LABA/GCS combination therapy via inhibiting phosphodiesterase 4 (PDE4) and/or blocking export of cAMP by ATP Binding Cassette Transporter C4 (ABCC4), will potentiate anti-inflammatory responses of mainstay LABA/GCS therapy. MethodsExpression and localization experiments were performed using in situ hybridization and immunohistochemistry in human lung tissue from healthy subjects, while confirmatory transcript and protein expression analyses were performed in primary human airway epithelial cells and cell lines. Intervention experiments were performed on the human airway epithelial cell line, HBEC-6KT, by pre-treatment with combinations of LABA/GCS with PDE4 and/or ABCC4 inhibitors followed by Poly I:C or imiquimod challenge as a model for viral stimuli. Cytokine readouts for IL-6, IL-8, CXCL10/IP-10, and CCL5/RANTES were quantified by ELISA. ResultsUsing archived human lung and human airway epithelial cells, ABCC4 gene and protein expression were confirmed in vitro and in situ. LABA/GCS attenuation of Poly I:C or imiquimod-induced IL-6 and IL-8 was potentiated with ABCC4 and PDE4 inhibition, which was greater when ABCC4 and PDE4 inhibition was combined. Modulation of cAMP levels had no impact on LABA/GCS modulation of Poly I:C-induced CXCL10/IP-10 or CCL5/RANTES. ConclusionModulation of intracellular cAMP levels by PDE4 or ABCC4 inhibition is able to potentiate LABA/GCS efficacy in human airway epithelial cells challenged with viral stimuli. The data suggests further exploration of the value of adding cAMP modulators to mainstay LABA/GCS therapy in asthma for potentiated anti-inflammatory efficacy.

immunology↗

bioRxiv2020

Early temporal dynamics of cellular responses to SARS-CoV-2

Type I interferons (IFNs) are our first line of defence against a virus. Protein over-expression studies have suggested the ability of SARS-CoV-2 proteins to block IFN responses. Emerging data also suggest that timing and extent of IFN production is associated with manifestation of COVID-19 severity. In spite of progress in understanding how SARS-CoV-2 activates antiviral responses, mechanistic studies into wildtype SARS-CoV-2-mediated induction and inhibition of human type I IFN responses are lacking. Here we demonstrate that SARS-CoV-2 infection induces a mild type I IFN response in vitro and in moderate cases of COVID-19. In vitro stimulation of type I IFN expression and signaling in human airway epithelial cells is associated with activation of canonical transcriptions factors, and SARS-CoV-2 is unable to inhibit exogenous induction of these responses. Our data demonstrate that SARS-CoV-2 is not adept in blocking type I IFN responses and provide support for ongoing IFN clinical trials. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/158154v2_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@193c540org.highwire.dtl.DTLVardef@7b106forg.highwire.dtl.DTLVardef@1741cfforg.highwire.dtl.DTLVardef@1bde68_HPS_FORMAT_FIGEXP M_FIG GRAPHICAL SUMMARY C_FIG

immunology↗

bioRxiv2020

Sequence, infectivity and replication kinetics of SARS-CoV-2 isolated from COVID-19 patients in Canada

SARS-CoV-2 emerged in December 2019 in Wuhan, China and has since infected over 1.5 million people, of which over 107,000 have died. As SARS-CoV-2 spreads across the planet, speculations remain about the range of human cells that can be infected by SARS-CoV-2. In this study, we report the isolation of SARS-CoV-2 from two COVID-19 patients in Toronto, Canada. We determined the genomic sequences of the two isolates and identified single nucleotide changes in representative populations of our virus stocks. More importantly, we tested a wide range of human immune cells for productive infection with SARS-CoV-2. Here we confirm that human primary peripheral blood mononuclear cells (PBMCs) are not permissive to SARS-CoV-2. As SARS-CoV-2 continues to spread globally, it is essential to monitor small nucleotide polymorphisms in the virus and to continue to isolate circulating viruses to determine cell susceptibility and pathogenicity using in vitro and in vivo infection models.

microbiology↗

bioRxiv2020

Gene expression and in situ protein profiling of candidate SARS-CoV-2 receptors in human airway epithelial cells and lung tissue

In December 2019, SARS-CoV-2 emerged causing the COVID-19 pandemic. SARS-CoV, the agent responsible for the 2003 SARS outbreak, utilizes ACE2 and TMPRSS2 host molecules for viral entry. ACE2 and TMPRSS2 have recently been implicated in SARS-CoV-2 viral infection. Additional host molecules including ADAM17, cathepsin L, CD147, and GRP78 may also function as receptors for SARS-CoV-2. To determine the expression and in situ localization of candidate SARS-CoV-2 receptors in the respiratory mucosa, we analyzed gene expression datasets from airway epithelial cells of 515 healthy subjects, gene promoter activity analysis using the FANTOM5 dataset containing 120 distinct sample types, single cell RNA sequencing (scRNAseq) of 10 healthy subjects, immunoblots on multiple airway epithelial cell types, and immunohistochemistry on 98 human lung samples. We demonstrate absent to low ACE2 promoter activity in a variety of lung epithelial cell samples and low ACE2 gene expression in both microarray and scRNAseq datasets of epithelial cell populations. Consistent with gene expression, rare ACE2 protein expression was observed in the airway epithelium and alveoli of human lung. We present confirmatory evidence for the presence of TMPRSS2, CD147, and GRP78 protein in vitro in airway epithelial cells and confirm broad in situ protein expression of CD147 in the respiratory mucosa. Collectively, our data suggest the presence of a mechanism dynamically regulating ACE2 expression in human lung, perhaps in periods of SARS-CoV-2 infection, and also suggest that alternate receptors for SARS-CoV-2 exist to facilitate initial host cell infection.

immunology↗