key: cord-0747485-a9bvuypk authors: Weiss, Anne; Touret, Franck; Baronti, Cecile; Gilles, Magali; Hoen, Bruno; Nougairède, Antoine; de Lamballerie, Xavier; Sommer, Morten Otto Alexander title: Niclosamide shows strong antiviral activity in a human airway model of SARS-CoV-2 infection and a conserved potency against the UK B.1.1.7 and SA B.1.351 variant date: 2021-04-26 journal: bioRxiv DOI: 10.1101/2021.04.26.441457 sha: be94d7c872ff6669d0ac4f2e731267c9fa57988f doc_id: 747485 cord_uid: a9bvuypk SARS-CoV-2 variants are emerging with potential increased transmissibility highlighting the great unmet medical need for new therapies. Niclosamide is a potent anti-SARS-CoV-2 agent that has advanced in clinical development. We validate the potent antiviral efficacy of niclosamide in a SARS-CoV-2 human airway model. Furthermore, niclosamide is effective against the D614G, B.1.1.7 and B.1.351 variants. Our data further support the potent anti-SARS-CoV-2 properties of niclosamide and highlights its great potential as a therapeutic agent for COVID-19. Since its emerge in 2019, coronavirus disease 2019 caused by severe acute respiratory 37 syndrome coronavirus 2 (SARS-CoV-2) led to over 3.1 million deaths worldwide as of April 26, 2021 (1) . 38 A tremendous joint research effort led to the approval of several vaccines at unprecedented speed yet anti-39 viral treatment options remain limited. At the same time, several viral variants harboring mutations in the 40 N-terminal (NTD) and receptor-binding domain (RBD) of the spike protein gene, such as the B.1.1.7 (also 41 named 20I/501Y.V1), B.1.351 (also named 20H/501Y.V2) variants, are causing global concern as they have 42 been associated with enhanced transmissibility and possible resistance to vaccines and antibody 43 neutralization (2-6). The B.1.1.7 and B.1.351 lineages have been linked to a ~50% increased transmission 44 of SARS-CoV-2 infection and the vaccine efficacy of ChAdOx1 nCoV-19 has been reported to be reduced 45 to 10.4% against the B.1.351 variant (6-9). Thus, despite the recent vaccine roll-out, there remains a high 46 unmet need for novel therapeutics against SARS-CoV-2, which should be effective against circulating and 47 potentially emerging variants of concern of SARS-CoV-2. 48 49 Niclosamide has been identified as a potent inhibitor of SARS-CoV-2 in vitro and in vivo and its optimized 50 formulation for intranasal application and inhalation, was well-tolerated in healthy volunteers in a Phase 1 51 trial (10-13). Herein, we sought to further characterize the anti-viral properties of niclosamide by 52 determining its potency in a human epithelial airway model of SARS-CoV-2 infection and tested its efficacy 53 against several variants of concern of SARS-CoV-2. 54 To strengthen the existing data on the potent antiviral activity of niclosamide with a preclinical model 56 resembling the human respiratory tract, we employed a trans-well bronchial human airway epithelium 57 (HAE) model infected with SARS-CoV-2. HAE cultured at an airway-liquid interface has been extensively 58 used as an in vitro physiological model mimicking the human mucociliary airway epithelium to validate the 59 effectivity of antivirals on infections in conducting airways (14-16). The effect of niclosamide on the 60 replication of SARS-CoV-2 in the HAE bronchial model (Eptihelix) was determined as previously described 61 by Touret et al. (17) and Pizzorno et al. (14) . 62 Briefly, human bronchial epithelial cells were apically infected with the European D614G strain of SARS-63 CoV-2 (BavPat1/2020; obtained from EVA-GLOBAL) at a MOI of 0.1 and cultivated in basolateral media 64 that contained different concentrations of niclosamide (in duplicates) or no drug (virus control) for up to 4 65 days. Media was renewed daily containing fresh niclosamide. Remdesivir was used as experimental positive 66 control and non-treated samples as negative control. On day 4, samples were collected at the apical side and 67 the viral titer was estimated with a TCID50 assay. Then, cells were lysed, and the intracellular viral RNA 68 was extracted and quantified by qRT-PCR. The viral inhibition was calculated with the infectious titers by 69 normalizing the response, having the bottom value as 100% and top value as 0%. The IC50 was determined 70 using logarithmic interpolation (Y=100/(1+10^((LogEC50-X)*HillSlope) in GraphPad Prims 7. Statistical 71 analysis was performed using the Ordinary One-way Anova with Dunnett's multiple comparisons test. These data are in line with the host-targeted mode of action of niclosamide, which has been described to 100 interfere with basic cellular mechanisms involved in SARS-CoV-2 replication, such as autophagy, the 101 endosomal pathway and the TMEM16A chloride channel (11, (19) (20) (21) . Accordingly, niclosamide is a potent 102 antiviral therapeutic agent against SARS-CoV-2 and its variants. The molecule will also deserve further 103 investigations to assess its potential role in the chemotherapeutic armamentarium required for future 104 emerging infectious disease preparedness. 105 106 Taken together, our findings support niclosamide's therapeutic potential as a potent anti-viral agent against 107 SARS-CoV-2, including its variants of concern. Trials in patients with COVID-19 are needed to substantiate 108 future clinical use. An interactive web-based dashboard to track COVID-19 in real 116 time Covid-19: Novavax vaccine efficacy is 86% against UK variant and 60% against 118 South African variant Announces Single-Shot Janssen COVID-19 Vaccine Candidate Met Primary 120 Endpoints in Interim Analysis of its Phase 3 ENSEMBLE Trial | Janssen Increased Resistance of SARS-CoV-2 Variants B.1.351 and B.1.1.7 to Antibody 124 Neutralization of N501Y mutant SARS-CoV-2 by 127 BNT162b2 vaccine-elicited sera Efficacy of the ChAdOx1 nCoV-19 Covid-19 Vaccine against the B Ferguson 137 NM. 2021. 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