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1.
Viruses ; 13(11)2021 11 04.
Article in English | MEDLINE | ID: covidwho-1538544

ABSTRACT

Pseudorabies virus (PRV) is the causative agent of Aujeszky's disease, which still causes large economic losses for the swine industry. Therefore, it is urgent to find a new strategy to prevent and control PRV infection. Previous studies have proven that guanine (G)-rich DNA or RNA sequences in some other viruses' genomes have the potential to form G-quadruplex (G4), which serve as promising antivirus targets. In this study, we identified two novel G4-forming sequences, OriL-A and OriL-S, which are located at the upstream origin of replication (OriL) in the PRV genome and conserved across 32 PRV strains. Circular dichroism (CD) spectroscopy and a gel electrophoresis assay showed that the two G-rich sequences can fold into parallel G4 structures in vitro. Moreover, fluorescence resonance energy transfer (FRET) melting and a Taq polymerase stop assay indicated that the G4 ligand PhenDC3 has the capacity to bind and stabilize the G4. Notably, the treatment of PRV-infected cells with G4-stabilizer PhenDC3 significantly inhibited PRV DNA replication in host cells but did not affect PRV's attachment and entry. These results not only expand our knowledge about the G4 characteristics in the PRV genome but also suggest that G4 may serve as an innovative therapeutic target against PRV.


Subject(s)
Antiviral Agents/pharmacology , G-Quadruplexes , Herpesvirus 1, Suid/genetics , Replication Origin/genetics , Animals , Antiviral Agents/chemistry , Cell Line , DNA Replication/drug effects , DNA, Viral/biosynthesis , DNA, Viral/chemistry , DNA, Viral/drug effects , Fused-Ring Compounds/chemistry , Fused-Ring Compounds/pharmacology , G-Quadruplexes/drug effects , Genome, Viral/drug effects , Genome, Viral/genetics , Herpesvirus 1, Suid/drug effects , Herpesvirus 1, Suid/physiology , Replication Origin/drug effects , Swine , Virus Replication/drug effects
2.
J Phys Chem Lett ; 11(14): 5661-5667, 2020 Jul 16.
Article in English | MEDLINE | ID: covidwho-1387115

ABSTRACT

Coronaviruses may produce severe acute respiratory syndrome (SARS). As a matter of fact, a new SARS-type virus, SARS-CoV-2, is responsible for the global pandemic in 2020 with unprecedented sanitary and economic consequences for most countries. In the present contribution we study, by all-atom equilibrium and enhanced sampling molecular dynamics simulations, the interaction between the SARS Unique Domain and RNA guanine quadruplexes, a process involved in eluding the defensive response of the host thus favoring viral infection of human cells. Our results evidence two stable binding modes involving an interaction site spanning either the protein dimer interface or only one monomer. The free energy profile unequivocally points to the dimer mode as the thermodynamically favored one. The effect of these binding modes in stabilizing the protein dimer was also assessed, being related to its biological role in assisting the SARS viruses to bypass the host protective response. This work also constitutes a first step in the possible rational design of efficient therapeutic agents aiming at perturbing the interaction between SARS Unique Domain and guanine quadruplexes, hence enhancing the host defenses against the virus.


Subject(s)
Betacoronavirus/chemistry , Betacoronavirus/genetics , Coronavirus Infections/virology , G-Quadruplexes/drug effects , Pneumonia, Viral/virology , RNA, Viral/chemistry , RNA, Viral/genetics , Betacoronavirus/drug effects , COVID-19 , Dimerization , Humans , Models, Molecular , Molecular Dynamics Simulation , Pandemics , Protein Binding , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/genetics
3.
Can J Physiol Pharmacol ; 99(5): 449-460, 2021 May.
Article in English | MEDLINE | ID: covidwho-1125455

ABSTRACT

Ribavirin is a guanosine analog with broad-spectrum antiviral activity against RNA viruses. Based on this, we aimed to show the anti-SARS-CoV-2 activity of this drug molecule via in vitro, in silico, and molecular techniques. Ribavirin showed antiviral activity in Vero E6 cells following SARS-CoV-2 infection, whereas the drug itself did not show any toxic effect over the concentration range tested. In silico analysis suggested that ribavirin has a broad-spectrum impact on SARS-CoV-2, acting at different viral proteins. According to the detailed molecular techniques, ribavirin was shown to decrease the expression of TMPRSS2 at both mRNA and protein levels 48 h after treatment. The suppressive effect of ribavirin in ACE2 protein expression was shown to be dependent on cell types. Finally, proteolytic activity assays showed that ribavirin also showed an inhibitory effect on the TMPRSS2 enzyme. Based on these results, we hypothesized that ribavirin may inhibit the expression of TMPRSS2 by modulating the formation of inhibitory G-quadruplex structures at the TMPRSS2 promoter. As a conclusion, ribavirin is a potential antiviral drug for the treatment against SARS-CoV-2, and it interferes with the effects of TMPRSS2 and ACE2 expression.


Subject(s)
Angiotensin-Converting Enzyme 2/metabolism , Antiviral Agents/pharmacology , Down-Regulation/drug effects , Ribavirin/pharmacology , SARS-CoV-2/drug effects , Serine Endopeptidases/metabolism , Animals , Caco-2 Cells , Chlorocebus aethiops , G-Quadruplexes/drug effects , Humans , Promoter Regions, Genetic/genetics , SARS-CoV-2/physiology , Serine Endopeptidases/genetics , Vero Cells
4.
Angew Chem Int Ed Engl ; 60(1): 432-438, 2021 01 04.
Article in English | MEDLINE | ID: covidwho-774564

ABSTRACT

The COVID-19 pandemic caused by SARS-CoV-2 has become a global threat. Understanding the underlying mechanisms and developing innovative treatments are extremely urgent. G-quadruplexes (G4s) are important noncanonical nucleic acid structures with distinct biofunctions. Four putative G4-forming sequences (PQSs) in the SARS-CoV-2 genome were studied. One of them (RG-1), which locates in the coding sequence region of SARS-CoV-2 nucleocapsid phosphoprotein (N), has been verified to form a stable RNA G4 structure in live cells. G4-specific compounds, such as PDP (pyridostatin derivative), can stabilize RG-1 G4 and significantly reduce the protein levels of SARS-CoV-2 N by inhibiting its translation both in vitro and in vivo. This result is the first evidence that PQSs in SARS-CoV-2 can form G4 structures in live cells, and that their biofunctions can be regulated by a G4-specific stabilizer. This finding will provide new insights into developing novel antiviral drugs against COVID-19.


Subject(s)
Antiviral Agents/pharmacology , COVID-19/drug therapy , G-Quadruplexes/drug effects , RNA, Viral/drug effects , SARS-CoV-2/drug effects , Drug Evaluation, Preclinical , Gene Expression Regulation, Viral/drug effects , Genome, Viral , Humans , Nucleocapsid Proteins/chemistry , Nucleocapsid Proteins/drug effects , Protein Folding , SARS-CoV-2/genetics , Small Molecule Libraries , Temperature
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