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1.
Sci Signal ; 15(729): eabg8744, 2022 04 12.
Article in English | MEDLINE | ID: covidwho-1784765

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused the unprecedented coronavirus disease 2019 (COVID-19) pandemic. Critical cases of COVID-19 are characterized by the production of excessive amounts of cytokines and extensive lung damage, which is partially caused by the fusion of SARS-CoV-2-infected pneumocytes. Here, we found that cell fusion caused by the SARS-CoV-2 spike (S) protein induced a type I interferon (IFN) response. This function of the S protein required its cleavage by proteases at the S1/S2 and the S2' sites. We further showed that cell fusion damaged nuclei and resulted in the formation of micronuclei that were sensed by the cytosolic DNA sensor cGAS and led to the activation of its downstream effector STING. Phosphorylation of the transcriptional regulator IRF3 and the expression of IFNB, which encodes a type I IFN, were abrogated in cGAS-deficient fused cells. Moreover, infection with VSV-SARS-CoV-2 also induced cell fusion, DNA damage, and cGAS-STING-dependent expression of IFNB. Together, these results uncover a pathway underlying the IFN response to SARS-CoV-2 infection. Our data suggest a mechanism by which fused pneumocytes in the lungs of patients with COVID-19 may enhance the production of IFNs and other cytokines, thus exacerbating disease severity.


Subject(s)
COVID-19 , Interferon Type I , COVID-19/genetics , Cell Fusion , Cytokines , Humans , Interferon Type I/genetics , Nucleotidyltransferases/genetics , Nucleotidyltransferases/metabolism , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/metabolism
2.
Antiviral Res ; 198: 105254, 2022 02.
Article in English | MEDLINE | ID: covidwho-1654045

ABSTRACT

Coronavirus disease 2019 (COVID-19) is a newly emerged infectious disease caused by a novel coronavirus, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The rapid global emergence of SARS-CoV-2 highlights the importance and urgency for potential drugs to control the pandemic. The functional importance of RNA-dependent RNA polymerase (RdRp) in the viral life cycle, combined with structural conservation and absence of closely related homologs in humans, makes it an attractive target for designing antiviral drugs. Nucleos(t)ide analogs (NAs) are still the most promising broad-spectrum class of viral RdRp inhibitors. In this study, using our previously developed cell-based SARS-CoV-2 RdRp report system, we screened 134 compounds in the Selleckchemicals NAs library. Four candidate compounds, Fludarabine Phosphate, Fludarabine, 6-Thio-20-Deoxyguanosine (6-Thio-dG), and 5-Iodotubercidin, exhibit remarkable potency in inhibiting SARS-CoV-2 RdRp. Among these four compounds, 5-Iodotubercidin exhibited the strongest inhibition upon SARS-CoV-2 RdRp, and was resistant to viral exoribonuclease activity, thus presenting the best antiviral activity against coronavirus from a different genus. Further study showed that the RdRp inhibitory activity of 5-Iodotubercidin is closely related to its capacity to inhibit adenosine kinase (ADK).


Subject(s)
Antiviral Agents/pharmacology , COVID-19/drug therapy , Nucleic Acid Synthesis Inhibitors/pharmacology , SARS-CoV-2/drug effects , Tubercidin/analogs & derivatives , Cell Line , Deoxyguanosine/analogs & derivatives , Deoxyguanosine/pharmacology , Drug Evaluation, Preclinical/methods , HEK293 Cells , Humans , Microbial Sensitivity Tests , RNA, Viral/biosynthesis , RNA-Dependent RNA Polymerase/antagonists & inhibitors , SARS-CoV-2/genetics , Thionucleosides/pharmacology , Tubercidin/pharmacology , Vidarabine/analogs & derivatives , Vidarabine/pharmacology , Vidarabine Phosphate/analogs & derivatives , Vidarabine Phosphate/pharmacology
3.
Antiviral Res ; 196: 105209, 2021 12.
Article in English | MEDLINE | ID: covidwho-1520691

ABSTRACT

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is the causative agent of Coronavirus Disease 2019 (COVID-19) pandemic. Despite intensive and global efforts to discover and develop novel antiviral therapies, only Remdesivir has been approved as a treatment for COVID-19. Therefore, effective antiviral therapeutics are still urgently needed to combat and halt the pandemic. Viral RNA-dependent RNA polymerase (RdRp) of SARS-CoV-2 demonstrates high potential as a reliable target for the development of antivirals. We previously developed a cell-based assay to assess the efficiency of compounds that target SARS-CoV-2 RdRp, as well as their tolerance to viral exoribonuclease-mediated proof-reading. In our previous study, we discovered that 2-((1H-indol-3-yl)thio)-N-phenyl-acetamides specifically targets the RdRp of both respiratory syncytial virus (RSV) and influenza A virus. Thus, we hypothesize that 2-((1H-indol-3-yl)thio)-N-phenyl-acetamides may also have the ability to inhibit SARS-CoV-2 replication by targeting its RdRp activity. In this research, we test a compound library containing 103 of 2-((1H-indol-3-yl)thio)-N-phenyl-acetamides against SARS-CoV-2 RdRp, using our cell-based assay. Among these compounds, the top five candidates strongly inhibit SARS-CoV-2 RdRp activity while exhibiting low cytotoxicity and resistance to viral exoribonuclease. Compound 6-72-2a is the most promising candidate with the lowest EC50 value of 1.41 µM and highest selectivity index (CC50/EC50) (above 70.92). Furthermore, our data suggests that 4-46b and 6-72-2a also inhibit the replication of HCoV-OC43 and HCoV-NL63 virus in a dose-dependent manner. Compounds 4-46b and 6-72-2a exhibit EC50 values of 1.13 µM and 0.94 µM, respectively, on HCoV-OC43 viral replication. However, higher concentrations of these compounds are needed to effectively block HCoV-NL63 replication. Together, our findings successfully identified 4-46b and 6-72-2a as promising inhibitors against SARS-CoV-2 RdRp.


Subject(s)
Acetamides/pharmacology , COVID-19/drug therapy , RNA-Dependent RNA Polymerase , Antiviral Agents/pharmacology , Drug Delivery Systems , Humans , RNA, Viral/biosynthesis , RNA-Dependent RNA Polymerase/antagonists & inhibitors , RNA-Dependent RNA Polymerase/drug effects , SARS-CoV-2/drug effects , Viral Proteins/antagonists & inhibitors , Viral Proteins/drug effects , Virus Replication/drug effects
4.
Eur J Med Chem ; 223: 113622, 2021 Nov 05.
Article in English | MEDLINE | ID: covidwho-1263253

ABSTRACT

The emerging severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the global pandemic coronavirus disease (COVID-19), but no specific antiviral drug has been proven effective for controlling this pandemic to date. In this study, several 2-((indol-3-yl)thio)-N-benzyl-acetamides were identified as SARS-CoV-2 RNA-dependent RNA polymerase (RdRp) inhibitors. After a two-round optimization, a new series of 2-((indol-3-yl)thio)-N-benzyl-acetamides was designed, synthesized, and evaluated for SARS-CoV-2 RdRp inhibitory effect. Compounds 6b2, 6b5, 6c9, 6d2, and 6d5 were identified as potent inhibitors with IC50 values of 3.35 ± 0.21 µM, 4.55 ± 0.2 µM, 1.65 ± 0.05 µM, 3.76 ± 0.79 µM, and 1.11 ± 0.05 µM, respectively; the IC50 of remdesivir (control) was measured as 1.19 ± 0.36 µM. All of the compounds inhibited RNA synthesis by SARS-CoV-2 RdRp. The most potent compound 6d5, which showed a stronger inhibitory activity against the human coronavirus HCoV-OC43 than remdesivir, is a promising candidate for further investigation.


Subject(s)
Acetamides/chemical synthesis , Antiviral Agents/chemical synthesis , COVID-19/drug therapy , Enzyme Inhibitors/chemical synthesis , RNA, Viral/antagonists & inhibitors , RNA-Dependent RNA Polymerase/antagonists & inhibitors , SARS-CoV-2/drug effects , Acetamides/pharmacology , Adenosine Monophosphate/analogs & derivatives , Adenosine Monophosphate/pharmacology , Adenosine Monophosphate/standards , Alanine/analogs & derivatives , Alanine/pharmacology , Alanine/standards , Antiviral Agents/pharmacology , Drug Evaluation, Preclinical , Enzyme Inhibitors/pharmacology , Humans , Inhibitory Concentration 50 , Molecular Docking Simulation , Molecular Structure , Protein Binding , SARS-CoV-2/genetics , Structure-Activity Relationship
5.
Natl Sci Rev ; 8(4): nwab006, 2021 Apr.
Article in English | MEDLINE | ID: covidwho-1254806

ABSTRACT

After a short recovery period, COVID-19 reinfections could occur in convalescent patients, even those with measurable levels of neutralizing antibodies. Effective vaccinations and protective public health measures are recommended for the convalescent COVID-19 patients.

6.
ACS Infect Dis ; 7(6): 1535-1544, 2021 06 11.
Article in English | MEDLINE | ID: covidwho-1243273

ABSTRACT

Coronavirus disease 2019 (COVID-19) is a fatal respiratory illness caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The identification of potential drugs is urgently needed to control the pandemic. RNA dependent RNA polymerase (RdRp) is a conserved protein within RNA viruses and plays a crucial role in the viral life cycle, thus making it an attractive target for development of antiviral drugs. In this study, 101 quinoline and quinazoline derivatives were screened against SARS-CoV-2 RdRp using a cell-based assay. Three compounds I-13e, I-13h, and I-13i exhibit remarkable potency in inhibiting RNA synthesis driven by SARS-CoV-2 RdRp and relatively low cytotoxicity. Among these three compounds, I-13e showed the strongest inhibition upon RNA synthesis driven by SARS-CoV-2 RdRp, the resistance to viral exoribonuclease activity and the inhibitory effect on the replication of CoV, thus holding potential of being drug candidate for treatment of SARS-CoV-2.


Subject(s)
Quinazolines , Quinolines , RNA-Dependent RNA Polymerase/antagonists & inhibitors , SARS-CoV-2/drug effects , Humans , Quinazolines/pharmacology , Quinolines/pharmacology , RNA, Viral/biosynthesis
7.
Antiviral Res ; 190: 105078, 2021 06.
Article in English | MEDLINE | ID: covidwho-1198616

ABSTRACT

Antiviral therapeutics is one effective avenue to control and end this devastating COVID-19 pandemic. The viral RNA-dependent RNA polymerase (RdRp) of SARS-CoV-2 has been recognized as a valuable target of antivirals. However, the cell-free SARS-CoV-2 RdRp biochemical assay requires the conversion of nucleotide prodrugs into the active triphosphate forms, which regularly occurs in cells yet is a complicated multiple-step chemical process in vitro, and thus hinders the utility of this cell-free assay in the rapid discovery of RdRp inhibitors. In addition, SARS-CoV-2 exoribonuclease provides the proof-reading capacity to viral RdRp, thus creates relatively high resistance threshold of viral RdRp to nucleotide analog inhibitors, which must be examined and evaluated in the development of this class of antivirals. Here, we report a cell-based assay to evaluate the efficacy of nucleotide analog compounds against SARS-CoV-2 RdRp and assess their tolerance to viral exoribonuclease-mediated proof-reading. By testing seven commonly used nucleotide analog viral polymerase inhibitors, Remdesivir, Molnupiravir, Ribavirin, Favipiravir, Penciclovir, Entecavir and Tenofovir, we found that both Molnupiravir and Remdesivir showed the strong inhibition of SARS-CoV-2 RdRp, with EC50 value of 0.22 µM and 0.67 µM, respectively. Moreover, our results suggested that exoribonuclease nsp14 increases resistance of SARS-CoV-2 RdRp to nucleotide analog inhibitors. We also determined that Remdesivir presented the highest resistance to viral exoribonuclease activity in cells. Therefore, we have developed a cell-based SARS-CoV-2 RdRp assay which can be deployed to discover SARS-CoV-2 RdRp inhibitors that are urgently needed to treat COVID-19 patients.


Subject(s)
Antiviral Agents/pharmacology , COVID-19/drug therapy , Drug Discovery , RNA-Dependent RNA Polymerase/antagonists & inhibitors , SARS-CoV-2/drug effects , SARS-CoV-2/enzymology , A549 Cells , Adenosine Monophosphate/analogs & derivatives , Adenosine Monophosphate/pharmacology , Alanine/analogs & derivatives , Alanine/pharmacology , COVID-19/virology , Cell Survival/drug effects , Exoribonucleases/antagonists & inhibitors , HEK293 Cells , High-Throughput Screening Assays , Humans , RNA, Viral/genetics , SARS-CoV-2/genetics , Viral Nonstructural Proteins/antagonists & inhibitors
8.
Acta Pharm Sin B ; 11(6): 1555-1567, 2021 Jun.
Article in English | MEDLINE | ID: covidwho-1082559

ABSTRACT

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has become one major threat to human population health. The RNA-dependent RNA polymerase (RdRp) presents an ideal target of antivirals, whereas nucleoside analogs inhibitor is hindered by the proofreading activity of coronavirus. Herein, we report that corilagin (RAI-S-37) as a non-nucleoside inhibitor of SARS-CoV-2 RdRp, binds directly to RdRp, effectively inhibits the polymerase activity in both cell-free and cell-based assays, fully resists the proofreading activity and potently inhibits SARS-CoV-2 infection with a low 50% effective concentration (EC50) value of 0.13 µmol/L. Computation modeling predicts that RAI-S-37 lands at the palm domain of RdRp and prevents conformational changes required for nucleotide incorporation by RdRp. In addition, combination of RAI-S-37 with remdesivir exhibits additive activity against anti-SARS-CoV-2 RdRp. Together with the current data available on the safety and pharmacokinetics of corilagin as a medicinal herbal agent, these results demonstrate the potential of being developed into one of the much-needed SARS-CoV-2 therapeutics.

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