Publications by authors named "Hadas Tamir"

10 Publications

  • Page 1 of 1

SARS-CoV-2 uses a multipronged strategy to impede host protein synthesis.

Nature 2021 06 12;594(7862):240-245. Epub 2021 May 12.

Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.

The coronavirus SARS-CoV-2 is the cause of the ongoing pandemic of COVID-19. Coronaviruses have developed a variety of mechanisms to repress host mRNA translation to allow the translation of viral mRNA, and concomitantly block the cellular innate immune response. Although several different proteins of SARS-CoV-2 have previously been implicated in shutting off host expression, a comprehensive picture of the effects of SARS-CoV-2 infection on cellular gene expression is lacking. Here we combine RNA sequencing, ribosome profiling and metabolic labelling of newly synthesized RNA to comprehensively define the mechanisms that are used by SARS-CoV-2 to shut off cellular protein synthesis. We show that infection leads to a global reduction in translation, but that viral transcripts are not preferentially translated. Instead, we find that infection leads to the accelerated degradation of cytosolic cellular mRNAs, which facilitates viral takeover of the mRNA pool in infected cells. We reveal that the translation of transcripts that are induced in response to infection (including innate immune genes) is impaired. We demonstrate this impairment is probably mediated by inhibition of nuclear mRNA export, which prevents newly transcribed cellular mRNA from accessing ribosomes. Overall, our results uncover a multipronged strategy that is used by SARS-CoV-2 to take over the translation machinery and to suppress host defences.
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http://dx.doi.org/10.1038/s41586-021-03610-3DOI Listing
June 2021

Glucosylceramide synthase inhibitors prevent replication of SARS-CoV-2 and Influenza virus.

J Biol Chem 2021 Feb 24:100470. Epub 2021 Feb 24.

Departments of Infectious diseases, Israel institute for Biological Research, Ness-Ziona, 7410000, Israel.

The ongoing COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a major threat to global health. Vaccines are ideal solutions to prevent infection, but treatments are also needed for those who have contracted the virus to limit negative outcomes, when vaccines are not applicable. Viruses must cross host cell membranes during their lifecycle, creating a dependency on processes involving membrane dynamics. Thus, in this study we examined whether the synthetic machinery for glycosphingolipids, biologically active components of cell membranes, can serve as a therapeutic target to combat SARS-CoV-2. We examined the antiviral effect of two specific inhibitors of glucosylceramide synthase (GCS); (i) Genz-123346, an analogue of the FDA-approved drug Cerdelga®, and (ii) GENZ-667161, an analogue of venglustat which is currently under phase III clinical trials. We found that both GCS inhibitors inhibit replication of SARS-CoV-2. Moreover, these inhibitors also disrupt replication of influenza virus A/PR/8/34 (H1N1). Our data imply that synthesis of glycosphingolipids is necessary to support viral life cycles, and suggest that GCS inhibitors should be further explored as antiviral therapies.
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http://dx.doi.org/10.1016/j.jbc.2021.100470DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7904475PMC
February 2021

Design of SARS-CoV-2 hFc-Conjugated Receptor-Binding Domain mRNA Vaccine Delivered Lipid Nanoparticles.

ACS Nano 2021 Jan 22. Epub 2021 Jan 22.

Laboratory of Precision NanoMedicine, Shmunis School for Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been identified as the causal agent of COVID-19 and stands at the center of the current global human pandemic, with death toll exceeding one million. The urgent need for a vaccine has led to the development of various immunization approaches. mRNA vaccines represent a cell-free, simple, and rapid platform for immunization, and therefore have been employed in recent studies toward the development of a SARS-CoV-2 vaccine. Herein, we present the design of an mRNA vaccine, based on lipid nanoparticles (LNPs)-encapsulated SARS-CoV-2 human Fc-conjugated receptor-binding domain (RBD-hFc). Several ionizable lipids have been evaluated in a luciferase (luc) mRNA reporter assay, and two leading LNPs formulations have been chosen for the subsequent RBD-hFc mRNA vaccine strategy. Intramuscular administration of LNP RBD-hFc mRNA elicited robust humoral response, a high level of neutralizing antibodies and a Th1-biased cellular response in BALB/c mice. The data in the current study demonstrate the potential of these lipids as promising candidates for LNP-based mRNA vaccines in general and for a COVID19 vaccine in particular.
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http://dx.doi.org/10.1021/acsnano.0c10180DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7860138PMC
January 2021

A single dose of recombinant VSV-∆G-spike vaccine provides protection against SARS-CoV-2 challenge.

Nat Commun 2020 12 16;11(1):6402. Epub 2020 Dec 16.

Israel Institute for Biological Research, Ness Ziona, Israel.

The COVID-19 pandemic caused by SARS-CoV-2 imposes an urgent need for rapid development of an efficient and cost-effective vaccine, suitable for mass immunization. Here, we show the development of a replication competent recombinant VSV-∆G-spike vaccine, in which the glycoprotein of VSV is replaced by the spike protein of SARS-CoV-2. In-vitro characterization of this vaccine indicates the expression and presentation of the spike protein on the viral membrane with antigenic similarity to SARS-CoV-2. A golden Syrian hamster in-vivo model for COVID-19 is implemented. We show that a single-dose vaccination results in a rapid and potent induction of SARS-CoV-2 neutralizing antibodies. Importantly, vaccination protects hamsters against SARS-CoV-2 challenge, as demonstrated by the abrogation of body weight loss, and  alleviation of the extensive tissue damage and viral loads in lungs and nasal turbinates. Taken together, we suggest the recombinant VSV-∆G-spike as a safe, efficacious and protective vaccine against SARS-CoV-2.
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http://dx.doi.org/10.1038/s41467-020-20228-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7745033PMC
December 2020

Detection and infectivity potential of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) environmental contamination in isolation units and quarantine facilities.

Clin Microbiol Infect 2020 Dec 10;26(12):1658-1662. Epub 2020 Sep 10.

Department of Infectious Diseases, Israel Institute for Biological Research, Ness Ziona, Israel. Electronic address:

Objectives: Environmental surfaces have been suggested as likely contributors in the transmission of COVID-19. This study assessed the infectivity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) contaminating surfaces and objects in two hospital isolation units and a quarantine hotel.

Methods: SARS-CoV-2 virus stability and infectivity on non-porous surfaces was tested under controlled laboratory conditions. Surface and air sampling were conducted at two COVID-19 isolation units and in a quarantine hotel. Viral RNA was detected by RT-PCR and infectivity was assessed by VERO E6 CPE test.

Results: In laboratory-controlled conditions, SARS-CoV-2 gradually lost its infectivity completely by day 4 at ambient temperature, and the decay rate of viral viability on surfaces directly correlated with increase in temperature. Viral RNA was detected in 29/55 surface samples (52.7%) and 16/42 surface samples (38%) from the surroundings of symptomatic COVID-19 patients in isolation units of two hospitals and in a quarantine hotel for asymptomatic and very mild COVID-19 patients. None of the surface and air samples from the three sites (0/97) were found to contain infectious titres of SARS-Cov-2 on tissue culture assay.

Conclusions: Despite prolonged viability of SARS-CoV-2 under laboratory-controlled conditions, uncultivable viral contamination of inanimate surfaces might suggest low feasibility for indirect fomite transmission.
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http://dx.doi.org/10.1016/j.cmi.2020.09.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7481174PMC
December 2020

The coding capacity of SARS-CoV-2.

Nature 2021 01 9;589(7840):125-130. Epub 2020 Sep 9.

Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of the ongoing coronavirus disease 2019 (COVID-19) pandemic. To understand the pathogenicity and antigenic potential of SARS-CoV-2 and to develop therapeutic tools, it is essential to profile the full repertoire of its expressed proteins. The current map of SARS-CoV-2 coding capacity is based on computational predictions and relies on homology with other coronaviruses. As the protein complement varies among coronaviruses, especially in regard to the variety of accessory proteins, it is crucial to characterize the specific range of SARS-CoV-2 proteins in an unbiased and open-ended manner. Here, using a suite of ribosome-profiling techniques, we present a high-resolution map of coding regions in the SARS-CoV-2 genome, which enables us to accurately quantify the expression of canonical viral open reading frames (ORFs) and to identify 23 unannotated viral ORFs. These ORFs include upstream ORFs that are likely to have a regulatory role, several in-frame internal ORFs within existing ORFs, resulting in N-terminally truncated products, as well as internal out-of-frame ORFs, which generate novel polypeptides. We further show that viral mRNAs are not translated more efficiently than host mRNAs; instead, virus translation dominates host translation because of the high levels of viral transcripts. Our work provides a resource that will form the basis of future functional studies.
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http://dx.doi.org/10.1038/s41586-020-2739-1DOI Listing
January 2021

A panel of human neutralizing mAbs targeting SARS-CoV-2 spike at multiple epitopes.

Nat Commun 2020 08 27;11(1):4303. Epub 2020 Aug 27.

Israel Institute for Biological Research, Ness-Ziona, Israel.

The novel highly transmissible human coronavirus SARS-CoV-2 is the causative agent of the COVID-19 pandemic. Thus far, there is no approved therapeutic drug specifically targeting this emerging virus. Here we report the isolation and characterization of a panel of human neutralizing monoclonal antibodies targeting the SARS-CoV-2 receptor binding domain (RBD). These antibodies were selected from a phage display library constructed using peripheral circulatory lymphocytes collected from patients at the acute phase of the disease. These neutralizing antibodies are shown to recognize distinct epitopes on the viral spike RBD. A subset of the antibodies exert their inhibitory activity by abrogating binding of the RBD to the human ACE2 receptor. The human monoclonal antibodies described here represent a promising basis for the design of efficient combined post-exposure therapy for SARS-CoV-2 infection.
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http://dx.doi.org/10.1038/s41467-020-18159-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7452893PMC
August 2020

Diagnosis of Imported Monkeypox, Israel, 2018.

Emerg Infect Dis 2019 05 17;25(5):980-983. Epub 2019 May 17.

We report a case of monkeypox in a man who returned from Nigeria to Israel in 2018. Virus was detected in pustule swabs by transmission electron microscopy and PCR and confirmed by immunofluorescence assay, tissue culture, and ELISA. The West Africa monkeypox outbreak calls for increased awareness by public health authorities worldwide.
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http://dx.doi.org/10.3201/eid2505.190076DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6478227PMC
May 2019

Differential Response Following Infection of Mouse CNS with Virulent and Attenuated Vaccinia Virus Strains.

Vaccines (Basel) 2019 Feb 12;7(1). Epub 2019 Feb 12.

Department of Infectious Diseases, Israel Institute of Biological Research (IIBR), Ness-Ziona, Israel.

Viral infections of the central nervous system (CNS) lead to a broad range of pathologies. CNS infections with Orthopox viruses have been mainly documented as an adverse reaction to smallpox vaccination with vaccinia virus. To date, there is insufficient data regarding the mechanisms underlying pathological viral replication or viral clearance. Therefore, informed risk assessment of vaccine adverse reactions or outcome prediction is limited. This work applied a model of viral infection of the CNS, comparing neurovirulent with attenuated strains. We followed various parameters along the disease and correlated viral load, morbidity, and mortality with tissue integrity, innate and adaptive immune response and functionality of the blood⁻brain barrier. Combining these data with whole brain RNA-seq analysis performed at different time points indicated that neurovirulence is associated with host immune silencing followed by induction of tissue damage-specific pathways. In contrast, brain infection with attenuated strains resulted in rapid and robust induction of innate and adaptive protective immunity, followed by viral clearance and recovery. This study significantly improves our understanding of the mechanisms and processes determining the consequence of viral CNS infection and highlights potential biomarkers associated with such outcomes.
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http://dx.doi.org/10.3390/vaccines7010019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6466266PMC
February 2019

Induction, treatment and prevention of eczema vaccinatum in atopic dermatitis mouse models.

Vaccine 2017 07 20;35(33):4245-4254. Epub 2017 Jun 20.

Department of Infectious Diseases, Israel Institute for Biological Research (IIBR), Ness-Ziona, Israel. Electronic address:

Eczema vaccinatum is a severe and occasionally lethal complication of smallpox vaccine, characterized by systemic viral dissemination, distant from the initial inoculation site of the vaccine. A major risk factor for eczema vaccinatum is a background of atopic dermatitis, a chronic, common allergic, relapsing disorder, manifested by dry and inflamed skin, itchy rash, Th2 biased immune response and hypersensitivity to various antigens. Unlike the severe manifestations of eczema vaccinatum in humans, current models present only mild symptoms that limits examination of potential therapeutics for eczema vaccinatum. The atopic dermatitis and eczema vaccinatum models we present here, are the first to simulate the severity of the diseases in humans. Indeed, dermatitic mice display persistent severe dermatitis, characterized by dry and inflamed skin with barrier dysfunction, epidermal hyperplasia and significant elevation of serum IgE. By exposing atopic dermatitis mice to ectromelia virus, we generated eczema vaccinatum that mimic the human disease better than known eczema vaccinatum models. Similarly to humans, eczematous mice displayed enlarged and disseminated skin lesions, which correlated with elevated viral load. Cidofovir and antiviral antibodies conferred protection even when treatment started at a late eczematous stage. Moreover, we are the first to demonstrate that despite a severe background of atopic dermatitis, modified vaccinia Ankara virus (MVA) vaccination protects against lethal ectromelia virus exposure. We finally show that protection by MVA vaccination is dependent on CD4 T cells and is associated with significant activation of CD8 cytotoxic T cells and induction of humoral immunity.
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http://dx.doi.org/10.1016/j.vaccine.2017.06.014DOI Listing
July 2017