Losartan promotes cell survival following SARS-CoV-2 infection in vitro

Introduction Coronavirus disease 2019 (COVID-19) can be associated with mortality and high morbidity worldwide. There is an extensive effort to control infection and disease caused by SARS-CoV-2. This study addressed the hypothesis that angiotensin II type I receptor blocker, Losartan, may restrict pathogenesis caused by SARS-CoV-2 by decreasing viral-induced cytopathological changes by blocking angiotensin II type 1 receptor (AT1R), thus reducing the affinity of the virus for ACE2, and inhibiting papain-like protease of the virus. Method Losartan inhibitory effect on deubiquitination and deISGylation properties of papain-like protease was investigated using a fluorescence method and gel shift analysis determining its inhibitory effects. The inhibitory effect of Losartan on SARS-CoV-2 cell replication was investigated both when losartan was added to the cell culture 1 hour before (pre-infection group) and 1 hour after (post-infection group) SARS-CoV-2 infection of Vero E6 cells. Results Losartan treatment of Vero E6 cells prior to and after SARS-CoV-2 infection reduced SARS-CoV-2 replication by 80% and 70% respectively. Losartan was not a strong deubiquitinase and deISGylase inhibitor of PLpro. Conclusion Losartan added pre- and post-infection to the Vero E6 cell culture significantly prevents cell destruction and replication by SARS-CoV2. Losartan has low side-effects, is readily available, and can be produced at high levels globally, all features of a promising drug in treatment of COVID-19 if validated by clinical trials. ### Competing Interest Statement The authors have declared no competing interest. * ACE : Angiotensin-Converting Enzyme ACE2 : Angiotensin-Converting Enzyme 2 AMC : C-terminal 7-amido-4-methylcoumarin Ang I : Angiotensin I Ang II : Angiotensin II Ang (1-7) : Angiotensin 1-7 Ang (1-9) : Angiotensin 1-9 ARB : angiotensin receptor blockers ARDS : acute respiratory distress syndrome AT1R : Angiotensin II type 1 receptor AT2R : Angiotensin II type 2 receptor BSA : bovine serum albumin CoV : coronavirus COVID-19 : coronavirus disease 2019; DMSO : dimethyl sulfoxide DUB : deubiquitinase GRL-0617 : 5-amino-2-methyl-Nbenzamide IL-6 : interleukin-6 ISG15 : interferon-stimulated gene product 15 MD : molecular dynamic MERS-CoV : Middle East Respiratory Syndrome NP : nuclear protein NSP : nonstructural proteins ORF1a/ORF1b : open reading frames PLP : papain-like protease PLpro : papain-like protease proISG15 : precursor ISG15 PRR : Pattern-Recognition Receptor RAS : renin-angiotensin system RBD : receptor binding domain SARS-CoV-2 : severe acute respiratory syndrome coronavirus 2 TLR : Toll-like receptor Tris : tris(hydroxymethyl)-aminomethane Ub : ubiquitin poly ub : polyubiquitin UIM : ubiquitin interacting motif