scholarly journals Lethal Mutagenesis of Picornaviruses with N-6-Modified Purine Nucleoside Analogues

2008 ◽  
Vol 52 (3) ◽  
pp. 971-979 ◽  
Author(s):  
Jason D. Graci ◽  
Kathleen Too ◽  
Eric D. Smidansky ◽  
Jocelyn P. Edathil ◽  
Eric W. Barr ◽  
...  
Keyword(s):  
Rna Viruses ◽  
Antiviral Agents ◽  
Antiviral Effect ◽  
Purine Nucleoside ◽  
Nucleoside Analogues ◽  
Genome Replication ◽  
Purine Analogues ◽  
Mutagenic Potential ◽  
Lethal Mutagenesis

ABSTRACT RNA viruses exhibit extraordinarily high mutation rates during genome replication. Nonnatural ribonucleosides that can increase the mutation rate of RNA viruses by acting as ambiguous substrates during replication have been explored as antiviral agents acting through lethal mutagenesis. We have synthesized novel N-6-substituted purine analogues with ambiguous incorporation characteristics due to tautomerization of the nucleobase. The most potent of these analogues reduced the titer of poliovirus (PV) and coxsackievirus (CVB3) over 1,000-fold during a single passage in HeLa cell culture, with an increase in transition mutation frequency up to 65-fold. Kinetic analysis of incorporation by the PV polymerase indicated that these analogues were templated ambiguously with increased efficiency compared to the known mutagenic nucleoside ribavirin. Notably, these nucleosides were not efficient substrates for cellular ribonucleotide reductase in vitro, suggesting that conversion to the deoxyriboucleoside may be hindered, potentially limiting genetic damage to the host cell. Furthermore, a high-fidelity PV variant (G64S) displayed resistance to the antiviral effect and mutagenic potential of these analogues. These purine nucleoside analogues represent promising lead compounds in the development of clinically useful antiviral therapies based on the strategy of lethal mutagenesis.

scholarly journals IFN-λ1 Displays Various Levels of Antiviral Activity In Vitro in a Select Panel of RNA Viruses

Viruses ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1602
Author(s):  
Marina Plotnikova ◽  
Alexey Lozhkov ◽  
Ekaterina Romanovskaya-Romanko ◽  
Irina Baranovskaya ◽  
Mariia Sergeeva ◽  
...  
Keyword(s):  
Antiviral Activity ◽  
Rna Viruses ◽  
Antiviral Effect ◽  
Vero Cells ◽  
Genome Replication ◽  
Type I ◽  
Protective Effects ◽  
Cellular Models ◽  
Viral Genome Replication

Type III interferons (lambda IFNs) are a quite new, small family of three closely related cytokines with interferon-like activity. Attention to IFN-λ is mainly focused on direct antiviral activity in which, as with IFN-α, viral genome replication is inhibited without the participation of immune system cells. The heterodimeric receptor for lambda interferons is exposed mainly on epithelial cells, which limits its possible action on other cells, thus reducing the likelihood of developing undesirable side effects compared to type I IFN. In this study, we examined the antiviral potential of exogenous human IFN-λ1 in cellular models of viral infection. To study the protective effects of IFN-λ1, three administration schemes were used: ‘preventive’ (pretreatment); ‘preventive/therapeutic’ (pre/post); and ‘therapeutic’ (post). Three IFN-λ1 concentrations (from 10 to 500 ng/mL) were used. We have shown that human IFN-λ1 restricts SARS-CoV-2 replication in Vero cells with all three treatment schemes. In addition, we have shown a decrease in the viral loads of CHIKV and IVA with the ‘preventive’ and ‘preventive/therapeutic’ regimes. No significant antiviral effect of IFN-λ1 against AdV was detected. Our study highlights the potential for using IFN-λ as a broad-spectrum therapeutic agent against respiratory RNA viruses.

scholarly journals Extinction of West Nile Virus by Favipiravir through Lethal Mutagenesis

2017 ◽  
Vol 61 (11) ◽  
Author(s):  
Estela Escribano-Romero ◽  
Nereida Jiménez de Oya ◽  
Esteban Domingo ◽  
Juan Carlos Saiz
Keyword(s):  
West Nile Virus ◽  
Mutation Frequency ◽  
Ebola Virus ◽  
Rna Viruses ◽  
Lethal Dose ◽  
Antiviral Agent ◽  
West Nile ◽  
Lethal Mutagenesis ◽  
Mutant Spectrum

ABSTRACT Favipiravir is an antiviral agent effective against several RNA viruses. The drug has been shown to protect mice against experimental infection with a lethal dose of West Nile virus (WNV), a mosquito-borne flavivirus responsible for outbreaks of meningitis and encephalitis for which no antiviral therapy has been licensed; however, the mechanism of action of the drug is still not well understood. Here, we describe the potent in vitro antiviral activity of favipiravir against WNV, showing that it decreases virus-specific infectivity and drives the virus to extinction. Two passages of WNV in the presence of 1 mM favipiravir—a concentration that is more than 10-fold lower than its 50% cytotoxic concentration (CC50)—resulted in a significant increase in mutation frequency in the mutant spectrum and in a bias toward A→G and G→A transitions relative to the population passaged in the absence of the drug. These data, together with the fact that the drug is already licensed in Japan against influenza virus and in a clinical trial against Ebola virus, point to favipiravir as a promising antiviral agent to fight medically relevant flaviviral infections, such as that caused by WNV.

scholarly journals Proofreading-Deficient Coronaviruses Adapt for Increased Fitness over Long-Term Passage without Reversion of Exoribonuclease-Inactivating Mutations

mBio ◽  
2017 ◽  
Vol 8 (6) ◽  
Author(s):  
Kevin W. Graepel ◽  
Xiaotao Lu ◽  
James Brett Case ◽  
Nicole R. Sexton ◽  
Everett Clinton Smith ◽  
...  
Keyword(s):  
Rna Viruses ◽  
Hepatitis Virus ◽  
Nucleoside Analogues ◽  
High Fidelity ◽  
Genome Replication ◽  
Murine Hepatitis Virus ◽  
Replicase Proteins ◽  
Rna Genome ◽  
Inactivating Mutations

ABSTRACT The coronavirus (CoV) RNA genome is the largest among the single-stranded positive-sense RNA viruses. CoVs encode a proofreading 3′-to-5′ exoribonuclease within nonstructural protein 14 (nsp14-ExoN) that is responsible for CoV high-fidelity replication. Alanine substitution of ExoN catalytic residues [ExoN(-)] in severe acute respiratory syndrome-associated coronavirus (SARS-CoV) and murine hepatitis virus (MHV) disrupts ExoN activity, yielding viable mutant viruses with defective replication, up to 20-fold-decreased fidelity, and increased susceptibility to nucleoside analogues. To test the stability of the ExoN(-) genotype and phenotype, we passaged MHV-ExoN(-) 250 times in cultured cells (P250), in parallel with wild-type MHV (WT-MHV). Compared to MHV-ExoN(-) P3, MHV-ExoN(-) P250 demonstrated enhanced replication and increased competitive fitness without reversion at the ExoN(-) active site. Furthermore, MHV-ExoN(-) P250 was less susceptible than MHV-ExoN(-) P3 to multiple nucleoside analogues, suggesting that MHV-ExoN(-) was under selection for increased replication fidelity. We subsequently identified novel amino acid changes within the RNA-dependent RNA polymerase and nsp14 of MHV-ExoN(-) P250 that partially accounted for the reduced susceptibility to nucleoside analogues. Our results suggest that increased replication fidelity is selected in ExoN(-) CoVs and that there may be a significant barrier to ExoN(-) reversion. These results also support the hypothesis that high-fidelity replication is linked to CoV fitness and indicate that multiple replicase proteins could compensate for ExoN functions during replication. IMPORTANCE Uniquely among RNA viruses, CoVs encode a proofreading exoribonuclease (ExoN) in nsp14 that mediates high-fidelity RNA genome replication. Proofreading-deficient CoVs with disrupted ExoN activity [ExoN(-)] either are nonviable or have significant defects in replication, RNA synthesis, fidelity, fitness, and virulence. In this study, we showed that ExoN(-) murine hepatitis virus can adapt during long-term passage for increased replication and fitness without reverting the ExoN-inactivating mutations. Passage-adapted ExoN(-) mutants also demonstrate increasing resistance to nucleoside analogues that is explained only partially by secondary mutations in nsp12 and nsp14. These data suggest that enhanced resistance to nucleoside analogues is mediated by the interplay of multiple replicase proteins and support the proposed link between CoV fidelity and fitness. IMPORTANCE Uniquely among RNA viruses, CoVs encode a proofreading exoribonuclease (ExoN) in nsp14 that mediates high-fidelity RNA genome replication. Proofreading-deficient CoVs with disrupted ExoN activity [ExoN(-)] either are nonviable or have significant defects in replication, RNA synthesis, fidelity, fitness, and virulence. In this study, we showed that ExoN(-) murine hepatitis virus can adapt during long-term passage for increased replication and fitness without reverting the ExoN-inactivating mutations. Passage-adapted ExoN(-) mutants also demonstrate increasing resistance to nucleoside analogues that is explained only partially by secondary mutations in nsp12 and nsp14. These data suggest that enhanced resistance to nucleoside analogues is mediated by the interplay of multiple replicase proteins and support the proposed link between CoV fidelity and fitness.

Effects of four nucleoside analogues used as antiviral agents on rat Sertoli cells (SerW3) in vitro

2016 ◽  
Vol 90 (8) ◽  
pp. 1975-1981 ◽  
Author(s):  
Runan Qiu ◽  
Aniko Horvath ◽  
Ralf Stahlmann
Keyword(s):  
Sertoli Cells ◽  
Antiviral Agents ◽  
Nucleoside Analogues

scholarly journals In vitro Assessment of Antiviral Effect of Natural Compounds on Porcine Epidemic Diarrhea Coronavirus

2021 ◽  
Vol 8 ◽  
Author(s):  
Manuel Gómez-García ◽  
Héctor Puente ◽  
Héctor Argüello ◽  
Óscar Mencía-Ares ◽  
Pedro Rubio ◽  
...  
Keyword(s):  
Antiviral Activity ◽  
Formic Acid ◽  
Antiviral Agents ◽  
Antiviral Effect ◽  
Vero Cells ◽  
Optical Microscope ◽  
Dependent Manner ◽  
Diarrhea Virus ◽  
Porcine Epidemic Diarrhea

Organic acid and essential oils (EOs), well-known antimicrobials, could also possess antiviral activity, a characteristic which has not been completely addressed up to now. In this study, the effect of two organic acids (formic acid and sodium salt of coconut fatty acid distillates) and two single EO compounds (thymol and cinnamaldehye) was evaluated against porcine epidemic diarrhea virus (PEDV). The concentration used for each compound was established by cytotoxicity assays in Vero cells. The antiviral activity was then evaluated at three multiplicities of infection (MOIs) through visual cytopathic effect (CPE) evaluation and an alamarBlue assay as well as real-time reverse-transcription PCR (RT-qPCR) and viral titration of cell supernatants. Formic acid at at a dose of 1,200 ppm was the only compound which showed antiviral activity, with a weak reduction of CPE caused by PEDV. Through the alamarBlue fluorescence assay, we showed a significant anti-CPE effect of formic acid which could not be observed by using an inverted optical microscope. RT-qPCR and infectivity analysis also showed that formic acid significantly reduced viral RNA and viral titers in a PEDV MOI-dependent manner. Our results suggest that the antiviral activity of formic acid could be associated to its inhibitory effect on viral replication. Further studies are required to explore the anti-PEDV activity of formic acid under field conditions alone or together with other antiviral agents.

scholarly journals KAY-2-41, a Novel Nucleoside Analogue Inhibitor of OrthopoxvirusesIn VitroandIn Vivo

2013 ◽  
Vol 58 (1) ◽  
pp. 27-37 ◽  
Author(s):  
Sophie Duraffour ◽  
Robert Drillien ◽  
Kazuhiro Haraguchi ◽  
Jan Balzarini ◽  
Dimitri Topalis ◽  
...  
Keyword(s):  
Binding Site ◽  
Nucleoside Analogue ◽  
Antiviral Agents ◽  
Antiviral Effect ◽  
Cross Resistance ◽  
Cowpox Virus ◽  
Herpes Simplex Virus 1 ◽  
Lethal Challenge ◽  
Atp Binding Site

ABSTRACTThe availability of adequate treatments for poxvirus infections would be valuable not only for human use but also for veterinary use. In the search for novel antiviral agents, a 1′-methyl-substituted 4′-thiothymidine nucleoside, designated KAY-2-41, emerged as an efficient inhibitor of poxviruses.In vitro, KAY-2-41 was active in the micromolar range against orthopoxviruses (OPVs) and against the parapoxvirus orf. The compound preserved its antiviral potency against OPVs resistant to the reference molecule cidofovir. KAY-2-41 had no noticeable toxicity on confluent monolayers, but a cytostatic effect was seen on growing cells. Genotyping of vaccinia virus (VACV), cowpox virus, and camelpox virus selected for resistance to KAY-2-41 revealed a nucleotide deletion(s) close to the ATP binding site or a nucleotide substitution close to the substrate binding site in the viral thymidine kinase (TK;J2R) gene. These mutations resulted in low levels of resistance to KAY-2-41 ranging from 2.7- to 6.0-fold and cross-resistance to 5-bromo-2′-deoxyuridine (5-BrdU) but not to cidofovir. The antiviral effect of KAY-2-41 relied, at least in part, on activation (phosphorylation) by the viral TK, as shown through enzymatic assays. The compound protected animals from disease and mortality after a lethal challenge with VACV, reduced viral loads in the serum, and abolished virus replication in tissues. In conclusion, KAY-2-41 is a promising nucleoside analogue for the treatment of poxvirus-induced diseases. Our findings warrant the evaluation of additional 1′-carbon-substituted 4′-thiothymidine derivatives as broad-spectrum antiviral agents, since this molecule also showed antiviral potency against herpes simplex virus 1 in earlier studies.

scholarly journals Effect of Ribavirin on the Mutation Rate and Spectrum of Hepatitis C Virus In Vivo

2009 ◽  
Vol 83 (11) ◽  
pp. 5760-5764 ◽  
Author(s):  
José M. Cuevas ◽  
Fernando González-Candelas ◽  
Andrés Moya ◽  
Rafael Sanjuán
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Mutation Rate ◽  
Rna Viruses ◽  
Mutagenic Effect ◽  
Significant Shift ◽  
Interferon Treatment ◽  
Lethal Mutagenesis

ABSTRACT Their extremely error-prone replication makes RNA viruses targets for lethal mutagenesis. In the case of hepatitis C virus (HCV), the standard treatment includes ribavirin, a base analog with an in vitro mutagenic effect, but the in vivo mode of action of ribavirin remains poorly understood. Here, we test the mutagenic effects of ribavirin plus interferon treatment in vivo using a new method to estimate mutation rates based on the analysis of nonsense mutations. We apply this methodology to a large HCV sequence database containing over 15,000 reverse transcription-PCR molecular clone sequences from 74 patients infected with HCV. We obtained an estimate of the spontaneous mutation rate of ca. 10−4 substitutions per site or lower, a value within the typically accepted range for RNA viruses. A roughly threefold increase in mutation rate and a significant shift in mutation spectrum were observed in samples from patients undergoing 6 months of interferon plus ribavirin treatment. This result is consistent with the known in vitro mutagenic effect of ribavirin and suggests that the antiviral effect of ribavirin plus interferon treatment is at least partly exerted through lethal mutagenesis.

scholarly journals Overcoming nonstructural protein 15-nidoviral uridylate-specific endoribonuclease (nsp15/NendoU) activity of SARS-CoV-2

2020 ◽  
Vol 2 (3) ◽  
pp. FDD42
Author(s):  
Suranga L Senanayake
Keyword(s):  
Broad Spectrum ◽  
Nonstructural Protein ◽  
Antiviral Agents ◽  
Nucleoside Analogs ◽  
Global Public Health ◽  
Health Crisis ◽  
Lethal Mutagenesis ◽  
Double Hit ◽  
Potential Inhibitors

COVID-19 has become the gravest global public health crisis since the Spanish Flu of 1918. Combination antiviral therapy with repurposed broad-spectrum antiviral agents holds a highly promising immediate treatment strategy, especially given uncertainties of vaccine efficacy and developmental timeline. Here, we describe a novel hypothetical approach: combining available broad-spectrum antiviral agents such as nucleoside analogs with potential inhibitors of NendoU, for example nsp15 RNA substrate mimetics. While only hypothesis-generating, this approach may constitute a ‘double-hit’ whereby two CoV-unique protein elements of the replicase–transcriptase complex are inhibited simultaneously; this may be an Achilles' heel and precipitate lethal mutagenesis in a coronavirus. It remains to be seen whether structurally optimized RNA substrate mimetics in combination with clinically approved and repurposed backbone antivirals can synergistically inhibit this endonuclease in vitro, thus fulfilling the ‘double-hit hypothesis’.

scholarly journals Lethal Mutagenesis of Poliovirus Mediated by a Mutagenic Pyrimidine Analogue

2007 ◽  
Vol 81 (20) ◽  
pp. 11256-11266 ◽  
Author(s):  
Jason D. Graci ◽  
Daniel A. Harki ◽  
Victoria S. Korneeva ◽  
Jocelyn P. Edathil ◽  
Kathleen Too ◽  
...  
Keyword(s):  
Antiviral Activity ◽  
Mechanism Of Action ◽  
Rna Viruses ◽  
Rna Virus ◽  
Virus Titer ◽  
High Fidelity ◽  
Mutational Robustness ◽  
Lethal Mutagenesis ◽  
The Impact

ABSTRACT Lethal mutagenesis is the mechanism of action of ribavirin against poliovirus (PV) and numerous other RNA viruses. However, there is still considerable debate regarding the mechanism of action of ribavirin against a variety of RNA viruses. Here we show by using T7 RNA polymerase-mediated production of PV genomic RNA, PV polymerase-catalyzed primer extension, and cell-free PV synthesis that a pyrimidine ribonucleoside triphosphate analogue (rPTP) with ambiguous base-pairing capacity is an efficient mutagen of the PV genome. The in vitro incorporation properties of rPTP are superior to ribavirin triphosphate. We observed a log-linear relationship between virus titer reduction and the number of rPMP molecules incorporated. A PV genome encoding a high-fidelity polymerase was more sensitive to rPMP incorporation, consistent with diminished mutational robustness of high-fidelity PV. The nucleoside (rP) did not exhibit antiviral activity in cell culture, owing to the inability of rP to be converted to rPMP by cellular nucleotide kinases. rP was also a poor substrate for herpes simplex virus thymidine kinase. The block to nucleoside phosphorylation could be bypassed by treatment with the P nucleobase, which exhibited both antiviral activity and mutagenesis, presumably a reflection of rP nucleotide formation by a nucleotide salvage pathway. These studies provide additional support for lethal mutagenesis as an antiviral strategy, suggest that rPMP prodrugs may be highly efficacious antiviral agents, and provide a new tool to determine the sensitivity of RNA virus genomes to mutagenesis as well as interrogation of the impact of mutational load on the population dynamics of these viruses.

scholarly journals Novel Nucleoside Analogues as Effective Antiviral Agents for Zika Virus Infections

Molecules ◽  
2020 ◽  
Vol 25 (20) ◽  
pp. 4813
Author(s):  
Marcella Bassetto ◽  
Cecilia M. Cima ◽  
Mattia Basso ◽  
Martina Salerno ◽  
Frank Schwarze ◽  
...  
Keyword(s):  
Zika Virus ◽  
Antiviral Agents ◽  
Antiviral Agent ◽  
Antiviral Effect ◽  
Health Concern ◽  
Virus Infections ◽  
Direct Acting Antiviral ◽  
Direct Acting ◽  
Further Development

Previously considered a neglected flavivirus, Zika virus has recently emerged as a public health concern due to its ability to spread rapidly and cause severe neurological disorders, such as microcephaly in newborn babies from infected mothers, and Guillain-Barré syndrome in adults. Despite extensive efforts towards the identification of effective therapies, specific antivirals are still not available. As part of ongoing medicinal chemistry studies to identify new antiviral agents, we screened against Zika virus replication in vitro in a targeted internal library of small-molecule agents, comprising both nucleoside and non-nucleoside agents. Among the compounds evaluated, novel aryloxyphosphoramidate prodrugs of the nucleosides 2′-C-methyl-adenosine, 2-CMA, and 7-deaza-2′C-methyl-adenosine, 7-DMA, were found to significantly inhibit the virus-induced cytopathic effect in multiple relevant cell lines. In addition, one of these prodrugs exhibits a synergistic antiviral effect against Zika virus when applied in combination with an indirect antiviral agent, a l-dideoxy bicyclic pyrimidine nucleoside analogue, which potently inhibits vaccinia and measles viruses in vitro by targeting a host pathway. Our findings provide a solid basis for further development of an antiviral therapy for Zika virus infections, possibly exploiting a dual approach combining two different agents, one targeting the viral polymerase (direct-acting antiviral), the second targeting a host-directed autophagy mechanism.

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