A small-molecule SARS-CoV-2 inhibitor targeting the membrane protein (preprint)

The membrane (M) protein of betacoronaviruses is well-conserved and plays a key role in viral assembly. Here, we describe the discovery of JNJ-9676, a novel small molecule targeting the coronaviral (CoV) M protein. JNJ-9676 demonstrates in vitro nanomolar antiviral activity against SARS-CoV2, SARS-CoV, and sarbecovirus strains from bat and pangolin zoonotic origin. Using cryogenic electron microscopy, we determined a novel binding pocket of JNJ-9676 in the M protein's transmembrane domain. Compound binding stabilized the M protein in an altered conformational state between its long- and short-forms, preventing the release of infectious virus. In a pre-exposure Syrian golden hamster model, JNJ-9676 (25 mg/kg BID) showed excellent efficacy illustrated by a significant reduction in viral load and infectious virus in the lung by 3.5 log10 and 4 log10, respectively. Histopathology scores at this dose were reduced to baseline. In a post-exposure hamster model, JNJ-9676 was efficacious at 75mg/kg BID even when added at 48 h post-infection, when peak viral loads were observed. The M protein is an attractive novel antiviral target to block coronavirus replication with JNJ-9676 representing an interesting chemical series towards identifying clinical candidates addressing the current and future CoV pandemics.

ACE2 mimetic antibody potently neutralizes all SARS-CoV-2 variants and fully protects in XBB.1.5 challenged monkeys (preprint)

The rapid evolution of SARS-CoV-2 to variants with improved transmission efficiency and reduced sensitivity to vaccine-induced humoral immunity has abolished the protective effect of licensed therapeutic human monoclonal antibodies (mAbs). To fill this unmet medical need and protect vulnerable patient populations, we isolated the P4J15 mAb from a previously infected, vaccinated donor, with <20 ng/ml neutralizing activity against all Omicron variants including the latest XBB.2.3 and EG.1 sub-lineages. Structural studies of P4J15 in complex with Omicron XBB.1 Spike show that the P4J15 epitope shares ~93% of its buried surface area with the ACE2 contact region, consistent with an ACE2 mimetic antibody. Although SARS-CoV-2 mutants escaping neutralization by P4J15 were selected in vitro, these displayed lower infectivity, poor binding to ACE2, and the corresponding "escape" mutations are accordingly rare in public sequence databases. Using a SARS-CoV-2 XBB.1.5 monkey challenge model, we show that P4J15 confers complete prophylactic protection. We conclude that the P4J15 mAb has potential as a broad-spectrum anti-SARS-CoV-2 drug.

SARS-CoV-2 Omicron potently neutralized by a novel antibody with unique Spike binding properties (preprint)

The SARS-CoV-2 Omicron variant exhibits very high levels of transmission, pronounced resistance to authorized therapeutic human monoclonal antibodies and reduced sensitivity to vaccine-induced immunity. Here we describe P2G3, a human monoclonal antibody (mAb) isolated from a previously infected and vaccinated donor, which displays picomolar-range neutralizing activity against Omicron BA.1, BA.1.1, BA.2 and all other current variants, and is thus markedly more potent than all authorized or clinically advanced anti-SARS-CoV-2 mAbs. Structural characterization of P2G3 Fab in complex with the Omicron Spike demonstrates unique binding properties to both down and up spike trimer conformations at an epitope that partially overlaps with the receptor-binding domain (RBD), yet is distinct from those bound by all other characterized mAbs. This distinct epitope and angle of attack allows P2G3 to overcome all the Omicron mutations abolishing or impairing neutralization by other anti-SARS-COV-2 mAbs, and P2G3 accordingly confers complete prophylactic protection in the SARS-CoV-2 Omicron monkey challenge model. Finally, although we could isolate in vitro SARS-CoV2 mutants escaping neutralization by P2G3 or by P5C3, a previously described broadly active Class 1 mAb, we found these viruses to be lowly infectious and their key mutations extremely rare in the wild, and we could demonstrate that P2G3/P5C3 efficiently cross-neutralized one another's escapees. We conclude that this combination of mAbs has great prospects in both the prophylactic and therapeutic settings to protect from Omicron and other VOCs.

Development and optimisation of a high-throughput screening assay for in vitro anti-SARS-CoV-2 activity: evaluation of 5676 phase 1 passed structures (preprint)

Although vaccines are currently used to control the coronavirus disease 2019 (COVID-19) pandemic, treatment options are urgently needed for those who cannot be vaccinated and for future outbreaks involving new severe acute respiratory syndrome coronavirus virus 2 (SARS-CoV-2) strains or coronaviruses not covered by current vaccines. Thus far, few existing antivirals are known to be effective against SARS-CoV-2 and clinically successful against COVID-19. As part of an immediate response to the COVID-19 pandemic, a high-throughput, high content imaging-based SARS-CoV-2 infection assay was developed in VeroE6-eGFP cells and was used to screen a library of 5676 compounds that passed phase 1 clinical trials. Eight candidates (nelfinavir, RG-12915, itraconazole, chloroquine, hydroxychloroquine, sematilide, remdesivir, and doxorubicin) with in vitro anti-SARS-CoV-2 activity in VeroE6-eGFP and/or Caco-2 cell lines were identified. However, apart from remdesivir, toxicity and pharmacokinetic data did not support further clinical development of these compounds for COVID-19 treatment.

Pan-ErbB inhibition protects from SARS-CoV-2 replication, inflammation, and injury (preprint)

Effective therapies are needed to combat emerging viruses. Seventeen candidates that rescue cells from SARS-CoV-2-induced lethality and target diverse functions emerged in a screen of 4,413 compounds. Among the hits was lapatinib, an approved inhibitor of the ErbB family of receptor tyrosine kinases. Lapatinib and other pan-ErbB inhibitors suppress replication of SARS-CoV-2 and unrelated viruses with a high barrier to resistance. ErbB4, but not lapatinib's cancer targets ErbB1 and ErbB2, is required for SARS-CoV-2 entry and Venezuelan equine encephalitis virus infection and is a molecular target mediating lapatinib's antiviral effect. In human lung organoids, lapatinib protects from SARS-CoV-2-induced activation of pathways implicated in acute and chronic lung injury downstream of ErbBs (p38-MAPK, MEK/ERK, and AKT/mTOR), pro-inflammatory cytokine production, and epithelial barrier injury. These findings reveal regulation of viral infection, inflammation, and tissue injury via ErbBs and propose approved candidates to counteract these effects with implications for coronaviruses and unrelated viruses.

A Highly Potent Antibody Effective Against SARS-CoV-2 Variants of Concern (preprint)

Control of the ongoing SARS-CoV-2 pandemic is endangered by the emergence of viral variants with increased transmission efficiency, resistance to marketed therapeutic antibodies and reduced sensitivity to vaccine-induced immunity. Here, we screened B cells from COVID-19 donors and identified P5C3, a highly potent and broadly neutralizing monoclonal antibody with picomolar neutralizing activity against all SARS-CoV-2 variants of concern (VOC) identified to date. Structural characterization of P5C3 Fab in complex with the Spike demonstrates a neutralizing activity defined by a large buried surface area, highly overlapping with the receptor-binding domain (RBD) surface necessary for ACE2 interaction. We further demonstrate that P5C3 showed complete prophylactic protection in the SARS-CoV-2 infected hamster challenge model. These results indicate that P5C3 opens exciting perspectives either as a prophylactic agent in immunocompromised individuals with poor response to vaccination or as combination therapy in SARS-CoV-2-infected individuals.Funding: This CARE project has received funding from the Innovative MedicinesInitiative 2 Joint Undertaking (JU) under grant agreement No 101005077. The JU receives support from the European Union’s Horizon 2020 research and innovation program and EFPIA and BILL & MELINDA GATES FOUNDATION, GLOBAL HEALTH DRUG DISCOVERYINSTITUTE, UNIVERSITY OF DUNDEE. Furthermore, funding was also provided through the Lausanne University Hospital, through the Swiss Vaccine Research Institute to G.P., and through the EPFL COVID fund to D.T.Conflict of Interest: None to declare. Ethical Approval: Study design and use of subject samples were approved by the Institutional Review Board of the Lausanne University Hospital and the ‘Commission d’éthique du Canton de Vaud’ (CER-VD).

Nelfinavir markedly improves lung pathology in SARS-CoV-2-infected Syrian hamsters despite a lack of an antiviral effect (preprint)

In response to the ongoing COVID-19 pandemic, repurposing of drugs for the treatment of SARS-CoV-2 infections is being explored. The FDA-approved HIV protease inhibitor Nelfinavir is one of the drugs that has been reported to inhibit in vitro SARS-CoV2 replication. We here report on the effect of Nelfinavir in the Syrian hamster SARS-CoV-2 infection model. Although treatment of infected hamsters with either 15 mg/kg BID or 50 mg/kg BID Nelfinavir [for four consecutive days, initiated on the day of infection] did not reduce viral RNA loads nor infectious virus titres in the lungs (as compared to the vehicle control at the end of treatment) the drug markedly improved virus-induced lung pathology at doses that were well tolerated. Yet, a massive interstitial infiltration of neutrophils was observed in the lungs of treated (infected and uninfected) animals. The protective effect of Nelfinavir on SARS-CoV-2-induced lung pathology that is unrelated to an antiviral effect warrants further exploration in the context of the treatment of COVID-19.

Environmentally-induced mdig is a major contributor to the severity of COVID-19 through fostering expression of SARS-CoV-2 receptor NRPs and glycan metabolism (preprint)

The novel {beta}-coronavirus, SARS-CoV-2, the causative agent of coronavirus disease 2019 (COVID-19), has infected more than 101 million people and resulted in 2.2 million death worldwide. Recent epidemiological studies suggested that some environmental factors, such as air pollution, might be the important contributors to the mortality of COVID-19. However, how environmental exposure enhances the severity of COVID-19 remains to be fully understood. In the present report, we provide evidence showing that mdig, a previously reported environmentally-induced oncogene that antagonizes repressive trimethylation of histone proteins, is a master regulator for SARS-CoV-2 receptors neuropilin-1 (NRP1) and NRP2, cathepsins, glycan metabolism and inflammation, key determinants for viral infection and cytokine storm of the patients. Depletion of mdig in bronchial epithelial cells by CRISPR-Cas-9 gene editing resulted in a decreased expression of NRP1, NRP2, cathepsins, and genes involved in protein glycosylation and inflammation, largely due to a substantial enrichment of lysine 9 and/or lysine 27 trimethylation of histone H3 (H3K9me3/H3K27me3) on these genes as determined by ChIP-seq. These data, accordingly, suggest that mdig is a key mediator for the severity of COVID-19 in response to environmental exposure and targeting mdig may be one of the effective strategies in ameliorating the symptom and reducing the mortality of COVID-19.

Identification of inhibitors of SARS-CoV-2 3CL-Pro enzymatic activity using a small molecule in-vitro repurposing screen (preprint)

Compound repurposing is an important strategy for the identification of effective treatment options against SARS-CoV-2 infection and COVID-19 disease. In this regard, SARS-CoV-2 main protease (3CL-Pro), also termed M-Pro, is an attractive drug target as it plays a central role in viral replication by processing the viral polyproteins pp1a and pp1ab at multiple distinct cleavage sites. We here report the results of a repurposing program involving 8.7 K compounds containing marketed drugs, clinical and preclinical candidates, and small molecules regarded as safe in humans. We confirmed previously reported inhibitors of 3CL-Pro, and have identified 62 additional compounds with IC50 values below 1 uM and profiled their selectivity towards Chymotrypsin and 3CL-Pro from the MERS virus. A subset of 8 inhibitors showed anti-cytopathic effect in a Vero-E6 cell line and the compounds thioguanosine and MG-132 were analysed for their predicted binding characteristics to SARS-CoV-2 3CL-Pro. The X-ray crystal structure of the complex of myricetin and SARS-Cov-2 3CL-Pro was solved at a resolution of 1.77 Angs., showing that myricetin is covalently bound to the catalytic Cys145 and therefore inhibiting its enzymatic activity.

One Year of SARS-CoV-2: How Much Has the Virus Changed? (preprint)

SARS-CoV-2 coronavirus has caused a world-wide crisis with profound effects on both healthcare and the economy. In order to combat the COVID-19 pandemic, research groups have shared viral genome sequence data through the GISAID initiative. We collected and computationally profiled ~223,000 full SARS-CoV-2 proteome sequences from GISAID over one year for emergent nonsynonymous mutations. Our analysis shows that SARS-CoV-2 proteins are mutating at substantially different rates, with most viral proteins exhibiting little mutational variability. As anticipated, our calculations capture previously reported mutations occurred in the first period of the pandemic, such as D614G (Spike), P323L (NSP12), and R203K/G204R (Nucleocapsid), but also identify recent mutations like A222V and L18F (Spike) and A220V (Nucleocapsid). Our comprehensive temporal and geographical analyses show two periods with different mutations in the SARS-CoV-2 proteome: December 2019 to June 2020 and July to November 2020. Some mutation rates differ also by geography; the main mutations in the second period occurred in Europe. Furthermore, our structure-based molecular analysis provides an exhaustive assessment of mutations in the context of 3D protein structure. Emerging sequence-to-structure data is beginning to reveal the site-specific mutational tolerance of SARS-CoV2 proteins as the virus continues to spread around the globe.

EXPERIMENTAL INVESTIGATION OF PULSE STERILIZATION OF VIRAL INFECTION (preprint)

The results of experimental investigations of the effect of high-intensity pulsed UV radiation on the influenza virus type A (H1N1) are presented. The research methodology is developed and the structure of the experiments is described. An end-face plasma accelerator was used as a radiation source, which provides a power pulsed discharge in an open atmosphere. The high efficiency of inactivation of the infectiousness of the virus was shown within a short period of time. The possibility of providing urgent 100% sterilization of a viral infection has been shown for the first time. A model for calculating the efficiency of pulse sterilization has been developed. The prospects for the application of pulse sterilization technology to combat coronavirus infection are considered.

Rapid SARS-CoV-2 Detection and Classification Using Phase Imaging with Computational Specificity (preprint)

Efforts to mitigate the COVID-19 crisis revealed that fast, accurate, and scalable testing is crucial for curbing the current impact and that of future pandemics. We propose an optical method for directly imaging unlabeled viral particles and using deep learning for detection and classification. An ultrasensitive interferometric method was used to image four virus types with nanoscale optical pathlength sensitivity. Pairing these data with fluorescence images for ground truth, we trained semantic segmentation models based on U-Net, a particular type of convolutional neural network. The trained network was applied to classify the viruses from the interferometric images only, containing simultaneously SARS-CoV-2, H1N1 (influenza-A), HAdV (adenovirus), and ZIKV (Zika). Remarkably, due to the nanoscale sensitivity in the input data, the neural network was able to identify SARS-CoV-2 vs. the other viruses with 96% accuracy. The inference time for each image is 60 ms, on a common graphic processing unit. This approach of directly imaging unlabeled viral particles may provide an extremely fast test, of less than a minute per patient. As the imaging instrument operates on regular glass slides, we envision this method as potentially testing on patient breath condensates. The necessary high throughput can be achieved by translating concepts from digital pathology, where a microscope can scan hundreds of slides automatically.

A blueprint for high affinity SARS-CoV-2 Mpro inhibitors from activity-based compound library screening guided by analysis of protein dynamics (preprint)

The SARS-CoV-2 coronavirus outbreak continues to spread at a rapid rate worldwide. The main protease (Mpro) is an attractive target for anti-COVID-19 agents. Unfortunately, unexpected difficulties have been encountered in the design of specific inhibitors. Here, by analyzing an ensemble of ~30,000 SARS-CoV-2 Mpro conformations from crystallographic studies and molecular simulations, we show that small structural variations in the binding site dramatically impact ligand binding properties. Hence, traditional druggability indices fail to adequately discriminate between highly and poorly druggable conformations of the binding site. By performing ~200 virtual screenings of compound libraries on selected protein structures, we redefine the protein's druggability as the consensus chemical space arising from the multiple conformations of the binding site formed upon ligand binding. This procedure revealed a unique SARS-CoV-2 Mpro blueprint that led to a definition of a specific structure-based pharmacophore. The latter explains the poor transferability of potent SARS-CoV Mpro inhibitors to SARS-CoV-2 Mpro, despite the identical sequences of the active sites. Importantly, application of the pharmacophore predicted novel high affinity inhibitors of SARS-CoV-2 Mpro, that were validated by in vitro assays performed here and by a newly solved X-ray crystal structure. These results provide a strong basis for effective rational drug design campaigns against SARS-CoV-2 Mpro and a new computational approach to screen protein targets with malleable binding sites.

Transfer Learning with MotifTransformers for Predicting Protein-Protein Interactions Between a Novel Virus and Humans (preprint)

The novel coronavirus SARS-CoV-2, which causes Coronavirus disease 2019 (COVID19), is a significant threat to worldwide public health. Viruses such as SARS-CoV-2 infect the human body by forming interactions between virus proteins and human proteins that compromise normal human protein-protein interactions (PPI). Current in vivo methods to identify PPIs between a novel virus and humans are slow, costly, and difficult to cover the vast interaction space. We propose a novel deep learning architecture designed for in silico PPI prediction and a transfer learning approach to predict interactions between novel virus proteins and human proteins. We show that our approach outperforms the state of the art methods significantly in predicting Virus-Human protein interactions for SARS-CoV-2, H1N1, and Ebola.

No detectable signal for ongoing genetic recombination in SARS-CoV-2 (preprint)

The COVID-19 pandemic has led to an unprecedented global sequencing effort of its viral agent SARS-CoV-2. The first whole genome assembly of SARS-CoV-2 was published on January 5 2020. Since then, over 150,000 high-quality SARS-CoV-2 genomes have been made available. This large genomic resource has allowed tracing of the emergence and spread of mutations and phylogenetic reconstruction of SARS-CoV-2 lineages in near real time. Though, whether SARS-CoV-2 undergoes genetic recombination has been largely overlooked to date. Recombination-mediated rearrangement of variants that arose independently can be of major evolutionary importance. Moreover, the absence of recombination is a key assumption behind the application of phylogenetic inference methods. Here, we analyse the extant genomic diversity of SARS-CoV-2 and show that, to date, there is no detectable hallmark of recombination. We assess our detection power using simulations and validate our method on the related MERS-CoV for which we report evidence for widespread genetic recombination.

Genomic diversity analysis of SARS-CoV-2 genomes in Rwanda (preprint)

COVID-19 (Coronavirus disease 2019) is an emerging pneumonia-like respiratory disease of humans and is recently spreading across the globe. To analyze the genome sequence of SARS-CoV-2 (severe acute respiratory syndrome coronavirus-2) isolated from Rwanda with other viral strains from African countries. We downloaded 75 genomes sequences of clinical SARS-CoV-2 from the GISAID (global initiative on sharing all influenza data) database and we comprehensively analyzed these SARS-CoV-2 genomes sequences alongside with Wuhan SARS-CoV-2 sequences as the reference strains. We analyzed 75 genomes sequences of SARS-CoV-2 isolated in different African countries including 10 samples of SARS-CoV-2 isolated in Rwanda between July and August 2020. The phylogenetic analysis of the genome sequence of SARS-CoV-2 revealed a strong identity with reference strains between 90-95%. We identified a missense mutation in four proteins including orf1ab polyprotein, NSP2, 2'-O-ribose methyltransferase and orf1a polyprotein. The most common changes in the base are C > T. We also found that all clinically SARS-CoV-2 isolated from Rwanda had genomes belonging to clade G and lineage B.1. Tracking the genetic evolution of SARS-CoV-2 over time is important to understand viral evolution pathogenesis. These findings may help to implement public health measures in curbing COVID-19 in Rwanda.

STAT2 signaling as double-edged sword restricting viral dissemination but driving severe pneumonia in SARS-CoV-2 infected hamsters (preprint)

Introductory paragraphSince the emergence of SARS-CoV-2 causing COVID-19, the world is being shaken to its core with numerous hospitalizations and hundreds of thousands of deaths. In search for key targets of effective therapeutics, robust animal models mimicking COVID-19 in humans are urgently needed. Here, we show that productive SARS-CoV-2 infection in the lungs of mice is limited and restricted by early type I interferon responses. In contrast, we show that Syrian hamsters are highly permissive to SARS- CoV-2 and develop bronchopneumonia and a strong inflammatory response in the lungs with neutrophil infiltration and edema. Moreover, we identify an exuberant innate immune response as a key player in pathogenesis, in which STAT2 signaling plays a dual role, driving severe lung injury on the one hand, yet restricting systemic virus dissemination on the other. Finally, we assess SARS-CoV- 2-induced lung pathology in hamsters by micro-CT alike used in clinical practice. Our results reveal the importance of STAT2-dependent interferon responses in the pathogenesis and virus control during SARS-CoV-2 infection and may help rationalizing new strategies for the treatment of COVID-19 patients.

Alpha-ketoamides as broad-spectrum inhibitors of coronavirus and enterovirus replication (preprint)

The main protease of coronaviruses and the 3C protease of enteroviruses share a similar active-site architecture and a unique requirement for glutamine in the P1 position of the substrate. Because of their unique specificity and essential role in viral polyprotein processing, these proteases are suitable targets for the development of antiviral drugs. In order to obtain near-equipotent, broad-spectrum antivirals against alphacoronaviruses, betacoronaviruses, and enteroviruses, we pursued structure-based design of peptidomimetic -ketoamides as inhibitors of main and 3C proteases. Six crystal structures of protease:inhibitor complexes were determined as part of this study. Compounds synthesized were tested against the recombinant proteases as well as in viral replicons and virus-infected cell cultures; most of them were not cell-toxic. Optimization of the P2 substituent of the -ketoamides proved crucial for achieving near-equipotency against the three virus genera. The best near-equipotent inhibitors, 11u (P2 = cyclopentylmethyl) and 11r (P2 = cyclohexylmethyl), display low-micromolar EC50 values against enteroviruses, alphacoronaviruses, and betacoronaviruses in cell cultures. In Huh7 cells, 11r exhibits three-digit picomolar activity against Middle East Respiratory Syndrome coronavirus.