Biology subjects

Melamed, S.

Publications and source records attributed to Melamed, S..

26 records · Page 2Linked to original sources

bioRxiv2021

A lipid nanoparticle RBD-hFc mRNA vaccine protects hACE2 transgenic mice against lethal SARS-CoV-2 infection

The current global COVID-19 pandemic led to an unprecedented effort to develop effective vaccines against SARS-CoV-2. mRNA vaccines were developed very rapidly during the last year, and became the leading immunization platform against the virus, with highly promising phase-3 results and remarkable efficacy data. Since most animal models are not susceptible to SARS CoV-2 infection, pre-clinical studies are often limited to infection-prone animals such as hamsters and non-human primates. In these animal models, SARS-CoV-2 infection results in viral replication and a mild disease disease. Therefore, the protective efficacy of the vaccine in these animals is commonly evaluated by its ability to elicit immunologic responses, diminish viral replication and prevent weight loss. Our lab recently reported the design of a SARS-CoV-2 human Fc-conjugated receptor-binding domain (RBD-hFc) mRNA vaccine delivered via lipid nanoparticles (LNPs). These experiments demonstrated the development of a robust and specific immunologic response in RBD-hFc mRNA-vaccinated BALB/c mice. In the current study, we evaluated the protective effect of this RBD-hFc mRNA vaccine by employing the K18-hACE2 mouse model. We report that administration of RBD-hFc mRNA vaccine to K18-hACE2 mice led to a robust humoral response comprised of both binding and neutralizing antibodies. In accordance with the recorded immunologic immune response, 70% of vaccinated mice were protected against a lethal dose (3000 plaque forming units) of SARS-CoV-2, while all control animals succumbed to infection. To the best of our knowledge, this is the first non-replicating mRNA vaccine study reporting protection of K18-hACE2 against a lethal SARS-CoV-2 infection.

microbiology↗

bioRxiv2020

Induced pulmonary comorbidities render CD-1 mice sensitive to SARS-CoV-2

Severe manifestations of COVID-19 are mostly restricted to people with comorbidities. Here we report that induced mild pulmonary morbidities render SARS-CoV-2-refractive CD-1 mice to be susceptible to this virus. Specifically, SARS-CoV-2 infection after application of low-doses of the acute-lung-injury stimulants bleomycin or ricin caused a severe disease in CD-1 mice, manifested by sustained body weight loss and mortality rates of >50%. Further studies revealed markedly higher levels of viral RNA in the lungs, heart and serum of low-dose-ricin pretreated, as compared to non-pretreated mice. Notably, the deleterious effects of SARS-CoV-2 infection were effectively alleviated by passive transfer of polyclonal or monoclonal antibodies generated against SARS-CoV-2 RBD. Thus, viral cell entry in the sensitized mice seems to involve viral RBD binding, albeit by a mechanism other than the canonical ACE2-mediated uptake route. In summary, we present a novel mice-based animal model for the study of comorbidity-dependent severe COVID-19.

pathology↗

bioRxiv2020

Post-exposure protection of SARS-CoV-2 lethal infected K18-hACE2 transgenic mice by neutralizing human monoclonal antibody

Coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), exhibits high levels of mortality and morbidity and has dramatic consequences on human life, sociality and global economy. Neutralizing antibodies constitute a highly promising approach for treating and preventing infection by this novel pathogen. In the present study, we characterized and further evaluated the recently identified human monoclonal MD65 antibody for its ability to provide protection against a lethal SARS-CoV-2 infection of K18-hACE2 transgenic mice. Eighty percent of the untreated mice succumbed 6-9 days post-infection while administration of the MD65 antibody as late as 3 days after exposure, rescued all infected animals. In addition, the efficiency of the treatment is supported by prevention of morbidity and ablation of the load of infective virions in the lungs of treated animals. The data unprecedentedly demonstrate, the therapeutic value of human monoclonal antibodies as a life-saving treatment of severe COVID-19 infection.

immunology↗

bioRxiv2020

Fibroblast fusion to the muscle fiber regulates myotendinous junction formation

Vertebrate muscles and tendons are derived from distinct embryonic origins yet they must interact in order to facilitate muscle contraction and body movements. How robust muscle tendon junctions (MTJs) form to be able to withstand contraction forces is still not understood. Using techniques at a single cell resolution we reexamined the classical view of distinct identities for the tissues composing the musculoskeletal system. We identified fibroblasts that have switched on a myogenic program and demonstrate these dual identity cells fuse into the developing muscle fibers along the MTJs facilitating the introduction of fibroblast-specific transcripts into the elongating myofibers. We suggest this mechanism resulting in a hybrid muscle fiber, primarily along the fiber tips, enables a smooth transition from muscle fiber characteristics towards tendon features essential for forming robust MTJs. We propose that dual characteristics of junctional cells could be a common mechanism for generating stable interactions between tissues throughout the musculoskeletal system.

developmental biology↗

bioRxiv2020

A single dose of recombinant VSV-{triangleup}G-spike vaccine provides protection against SARS-CoV-2 challenge

The COVID-19 pandemic caused by SARS-CoV-2 that emerged in December 2019 in China resulted in over 7.8 million infections and over 430,000 deaths worldwide, imposing an urgent need for rapid development of an efficient and cost-effective vaccine, suitable for mass immunization. Here, we generated a replication competent recombinant VSV-{Delta}G-spike vaccine, in which the glycoprotein of VSV was replaced by the spike protein of the SARS-CoV-2. In vitro characterization of the recombinant VSV-{Delta}G-spike indicated 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 was implemented. We show that vaccination of hamsters with recombinant VSV-{Delta}G-spike results in rapid and potent induction of neutralizing antibodies against SARS-CoV-2. Importantly, single-dose vaccination was able to protect hamsters against SARS-CoV-2 challenge, as demonstrated by the abrogation of body weight loss of the immunized hamsters compared to unvaccinated hamsters. Furthermore, whereas lungs of infected hamsters displayed extensive tissue damage and high viral titers, immunized hamsters lungs showed only minor lung pathology, and no viral load. Taken together, we suggest recombinant VSV-{Delta}G-spike as a safe, efficacious and protective vaccine against SARS-CoV-2 infection.

microbiology↗

bioRxiv2020

Tiger team: a panel of human neutralizing mAbs targeting SARS-CoV-2 spike at multiple epitopes

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, therefore they represent a promising basis for the design of efficient combined post-exposure therapy for SARS-CoV-2 infection.

immunology↗

bioRxiv2020

Antiviral activity of Glucosylceramide synthase inhibitors against SARS-CoV-2 and other RNA virus infections

The need for antiviral drugs is real and relevant. Broad spectrum antiviral drugs have a particular advantage when dealing with rapid disease outbreaks, such as the current COVID-19 pandemic. Since viruses are completely dependent on internal cell mechanisms, they must cross cell membranes during their lifecycle, creating a dependence on processes involving membrane dynamics. Thus, in this study we examined whether the synthesis of glycosphingolipids, biologically active components of cell membranes, can serve as an antiviral therapeutic target. We examined the antiviral effect of two specific inhibitors of GlucosylCeramide synthase (GCS); (i) Genz-123346, an analogue of the FDA-approved drug Cerdelga(R), (ii) GENZ-667161, an analogue of venglustat which is currently under phase III clinical trials. We found that both GCS inhibitors inhibit the replication of four different enveloped RNA viruses of different genus, organ-target and transmission route: (i) Neuroinvasive Sindbis virus (SVNI), (ii) West Nile virus (WNV), (iii) Influenza A virus, and (iv) SARS-CoV-2. Moreover, GCS inhibitors significantly increase the survival rate of SVNI-infected mice. Our data suggest that GCS inhibitors can potentially serve as a broad-spectrum antiviral therapy and should be further examined in preclinical and clinical trial. Analogues of the specific compounds tested have already been studied clinically, implying they can be fast-tracked for public use. With the current COVID-19 pandemic, this may be particularly relevant to SARS-CoV-2 infection. One Sentence SummaryAn analogue of Cerdelga(R), an FDA-approved drug, is effective against a broad range of RNA-viruses including the newly emerging SARS-CoV-2.

microbiology↗

bioRxiv2020

The coding capacity of SARS-CoV-2

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of the ongoing Coronavirus disease 19 (COVID-19) pandemic 1,2. In order to understand SARS-CoV-2 pathogenicity and antigenic potential, and to develop diagnostic and therapeutic tools, it is essential to portray the full repertoire of its expressed proteins. The SARS-CoV-2 coding capacity map is currently based on computational predictions and relies on homology to other coronaviruses. Since coronaviruses differ in their protein array, especially in the variety of accessory proteins, it is crucial to characterize the specific collection of SARS-CoV-2 proteins in an unbiased and open-ended manner. Utilizing a suite of ribosome profiling techniques 3-8, we present a high-resolution map of the SARS-CoV-2 coding regions, allowing us to accurately quantify the expression of canonical viral open reading frames (ORF)s and to identify 23 novel unannotated viral translated ORFs. These ORFs include upstream ORFs (uORFs) that are likely playing a regulatory role, several in-frame internal ORFs lying 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; rather, virus translation dominates host translation due to high levels of viral transcripts. Overall, our work reveals the full coding capacity of SARS-CoV-2 genome, providing a rich resource, which will form the basis of future functional studies and diagnostic efforts.

microbiology↗