#AZT acts as an anti- #influenza nucleotide triphosphate targeting the catalytic site of A/PR/8/34/ #H1N1 RNA dependent RNA #polymerase (J Comput Aided Mol Des., abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

J Comput Aided Mol Des. 2019 Feb 9. doi: 10.1007/s10822-019-00189-w. [Epub ahead of print]

AZT acts as an anti-influenza nucleotide triphosphate targeting the catalytic site of A/PR/8/34/H1N1 RNA dependent RNA polymerase.

Pagadala NS1,2,3,4.

Author information: 1 Li Ka Shing Institute of Virology, University of Alberta, Edmonton, AB, Canada. nattu251@gmail.com. 2 Li Ka Shing Applied Virology Institute, University of Alberta, Edmonton, AB, Canada. nattu251@gmail.com. 3 Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB, Canada. nattu251@gmail.com. 4 Medical Microbiology and Immunology, Li Ka Shing Institute of Virology, University of Alberta, Edmonton, AB, T6G 2E1, Canada. nattu251@gmail.com.

 

Abstract

To develop potent drugs that inhibit the activity of influenza virus RNA dependent RNA polymerase (RdRp), a set of compounds favipiravir, T-705, T-1105 and T-1106, ribavirin, ribavirin triphosphate viramidine, 2FdGTP (2′-deoxy-2′-fluoroguanosine triphosphate) and AZT-TP (3′-Azido-3′-deoxy-thymidine-5′-triphosphate) were docked with a homology model of IAV RdRp from the A/PR/8/34/H1N1 strain. These compounds bind to four pockets A-D of the IAV RdRp with different mechanism of action. In addition, AZT-TP also binds to the PB1 catalytic site near to the tip of the priming loop with a highest ΔG of - 16.7 Kcal/mol exhibiting an IC50 of 1.12 µM in an in vitro enzyme transcription assay. This shows that AZT-TP mainly prevents the incorporation of incoming nucleotide involved in initiation of vRNA replication. Conversely, 2FdGTP used as a positive control binds to pocket-B at the end of tunnel-II with a highest ΔG of - 16.3 Kcal/mol inhibiting chain termination with a similar IC50 of 1.12 µM. Overall, our computational results in correlation with experimental studies gives information for the first time about the binding modes of the known influenza antiviral compounds in different models of vRNA replication by IAV RdRp. This in turn gives new structural insights for the development of new therapeutics exhibiting high specificity to the PB1 catalytic site of influenza A viruses.

KEYWORDS: Catalytic site; Docking; Nucleotide triphosphates; RNA dependent RNA polymerase

PMID: 30739239 DOI: 10.1007/s10822-019-00189-w

Keywords: Influenza A; H1N1; Antivirals; AZT; Ribavirin; Favipiravir.

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#Filovirus #Virulence in #Interferon α/β and γ Double Knockout Mice, and #Treatment with #Favipiravir (Viruses, abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

Viruses. 2019 Feb 3;11(2). pii: E137. doi: 10.3390/v11020137.

Filovirus Virulence in Interferon α/β and γ Double Knockout Mice, and Treatment with Favipiravir.

Comer JE1,2,3,4, Escaffre O5, Neef N6, Brasel T7,8,9, Juelich TL10, Smith JK11, Smith J12, Kalveram B13, Perez DD14, Massey S15, Zhang L16, Freiberg AN17,18,19,20.

Author information: 1 Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA. jscomer@UTMB.edu. 2 Office of Regulated Nonclinical Studies, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA. jscomer@UTMB.edu. 3 Sealy Institute for Vaccine Science, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA. jscomer@UTMB.edu. 4 The Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA. jscomer@UTMB.edu. 5 Department of Pathology, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA. olescaff@utmb.edu. 6 Experimental Pathology Laboratories, Inc., Sterling, VA 20167, USA. nneef@7thwavelabs.com. 7 Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA. trbrasel@utmb.edu. 8 Office of Regulated Nonclinical Studies, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA. trbrasel@utmb.edu. 9 Sealy Institute for Vaccine Science, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA. trbrasel@utmb.edu. 10 Department of Pathology, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA. tljuelic@utmb.edu. 11 Department of Pathology, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA. jeksmith@UTMB.EDU. 12 Office of Regulated Nonclinical Studies, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA. jensmit1@utmb.edu. 13 Department of Pathology, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA. bkkalver@utmb.edu. 14 Department of Pathology, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA. dadperez@tamu.edu. 15 Office of Regulated Nonclinical Studies, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA. chmassey@utmb.edu. 16 Department of Pathology, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA. lihzhang@utmb.edu. 17 Sealy Institute for Vaccine Science, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA. anfreibe@utmb.edu. 18 The Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA. anfreibe@utmb.edu. 19 Department of Pathology, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA. anfreibe@utmb.edu. 20 Institute for Human Infections and Immunity, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA. anfreibe@utmb.edu.

 

Abstract

The 2014 Ebolavirus outbreak in West Africa highlighted the need for vaccines and therapeutics to prevent and treat filovirus infections. A well-characterized small animal model that is susceptible to wild-type filoviruses would facilitate the screening of anti-filovirus agents. To that end, we characterized knockout mice lacking α/β and γ interferon receptors (IFNAGR KO) as a model for wild-type filovirus infection. Intraperitoneal challenge of IFNAGR KO mice with several known human pathogenic species from the genus Ebolavirus and Marburgvirus, except Bundibugyo ebolavirus and Taï Forest ebolavirus, caused variable mortality rate. Further characterization of the prototype Ebola virus Kikwit isolate infection in this KO mouse model showed 100% lethality down to a dilution equivalent to 1.0 × 10-1 pfu with all deaths occurring between 7 and 9 days post-challenge. Viral RNA was detectable in serum after challenge with 1.0 × 10² pfu as early as one day after infection. Changes in hematology and serum chemistry became pronounced as the disease progressed and mirrored the histological changes in the spleen and liver that were also consistent with those described for patients with Ebola virus disease. In a proof-of-principle study, treatment of Ebola virus infected IFNAGR KO mice with favipiravir resulted in 83% protection. Taken together, the data suggest that IFNAGR KO mice may be a useful model for early screening of anti-filovirus medical countermeasures.

KEYWORDS: Ebola virus; filovirus; interferon receptor knockout; mouse

PMID: 30717492 DOI: 10.3390/v11020137 Free full text

Keywords: Filovirus; Ebola; Marburg; Ebola Bundibugyo; Tai Forest Virus; Favipiravir; Antivirals; Animal models.

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#Influenza virus #polymerase #inhibitors in #clinical development (Curr Opin Infect Dis., abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

Curr Opin Infect Dis. 2019 Feb 4. doi: 10.1097/QCO.0000000000000532. [Epub ahead of print]

Influenza virus polymerase inhibitors in clinical development.

Hayden FG1, Shindo N2.

Author information: 1 Department of Medicine, University of Virginia School of Medicine, Charlottesville, Virginia, USA. 2 Health Emergencies Program, World Health Organization, Geneva, Switzerland.

 

Abstract

PURPOSE OF REVIEW:

We review antivirals inhibiting subunits of the influenza polymerase complex that are advancing in clinical development.

RECENT FINDINGS:

Favipiravir, pimodivir, and baloxavir are inhibitory in preclinical models for influenza A viruses, including pandemic threat viruses and those resistant to currently approved antivirals, and two (favipiravir and baloxavir) also inhibit influenza B viruses. All are orally administered, although the dosing regimens vary. The polymerase basic protein 1 transcriptase inhibitor favipiravir has shown inconsistent clinical effects in uncomplicated influenza, and is teratogenic effects in multiple species, contraindicating its use in pregnancy. The polymerase basic protein 2 cap-binding inhibitor pimodivir displays antiviral effects alone and in combination with oseltamivir in uncomplicated influenza, although variants with reduced susceptibility emerge frequently during monotherapy. Single doses of the polymerase acidic protein cap-dependent endonuclease inhibitor baloxavir are effective in alleviating symptoms and rapidly inhibiting viral replication in otherwise healthy and higher risk patients with acute influenza, although variants with reduced susceptibility emerge frequently during monotherapy. Combinations of newer polymerase inhibitors with neuraminidase inhibitors show synergy in preclinical models and are currently undergoing clinical testing in hospitalized patients.

SUMMARY:

These new polymerase inhibitors promise to add to the clinical management options and overall control strategies for influenza virus infections.

PMID: 30724789 DOI: 10.1097/QCO.0000000000000532

Keywords: Antivirals; Drugs Resistance; Influenza A; Pandemic Influenza; Favipiravir; Pimodivir; Baloxavir.

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Optimizing T-705 (#favipiravir) #treatment of #severe #influenza B virus infection in the immunocompromised mouse model (J Antimicrob Chemother., abstract)

[Source: Journal of Antimicrobial Chemotherapy, full page: (LINK). Abstract, edited.]

Optimizing T-705 (favipiravir) treatment of severe influenza B virus infection in the immunocompromised mouse model

Philippe Noriel, Q Pascua, Bindumadhav M Marathe, Peter Vogel, Richard J Webby, Elena A Govorkova

Journal of Antimicrobial Chemotherapy, dky560, https://doi.org/10.1093/jac/dky560

Published: 30 January 2019

 

Abstract

Background

Influenza B virus infections remain insufficiently studied and antiviral management in immunocompromised patients is not well defined. The treatment regimens for these high-risk patients, which have elevated risk of severe disease-associated complications, require optimization and can be partly addressed via animal models.

Methods

We examined the efficacy of monotherapy with the RNA-dependent RNA polymerase inhibitor T-705 (favipiravir) in protecting genetically modified, permanently immunocompromised BALB scid mice against lethal infection with B/Brisbane/60/2008 (BR/08) virus. Beginning at 24 h post-infection, BALB scidmice received oral T-705 twice daily (10, 50 or 250 mg/kg/day) for 5 or 10 days.

Results

T-705 had a dose-dependent effect on survival after BR/08 challenge, resulting in 100% protection at the highest dosages. With the 5 day regimens, dosages of 50 or 250 mg/kg/day reduced the peak lung viral titres within the treatment window, but could not efficiently clear the virus after completion of treatment. With the 10 day regimens, dosages of 50 or 250 mg/kg/day significantly suppressed virus replication in the lungs, particularly at 45 days post-infection, limiting viral spread and pulmonary pathology. No T-705 regimen decreased virus growth in the nasal turbinates of mice, which potentially contributed to the viral dynamics in the lungs. The susceptibility of influenza B viruses isolated from T-705-treated mice remained comparable to that of viruses from untreated control animals.

Conclusions

T-705 treatment is efficacious against lethal challenge with BR/08 virus in immunocompromised mice. The antiviral benefit was greatest when longer T-705 treatment was combined with higher dosages.

Issue Section: ORIGINAL RESEARCH

© The Author(s) 2019. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For permissions, please email: journals.permissions@oup.com.

This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Keywords: Seasonal Influenza; Influenza B; Antivirals; Favipiravir; Animal models.

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#Combination #Therapy with #Oseltamivir and #Favipiravir Delays #Mortality but Does Not Prevent Oseltamivir #Resistance in Immunodeficient Mice Infected with #H1N1pdm09 Influenza Virus (Viruses, abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

Viruses. 2018 Nov 3;10(11). pii: E610. doi: 10.3390/v10110610.

Combination Therapy with Oseltamivir and Favipiravir Delays Mortality but Does Not Prevent Oseltamivir Resistance in Immunodeficient Mice Infected with Pandemic A(H1N1) Influenza Virus.

Baz M1, Carbonneau J2, Rhéaume C3, Cavanagh MH4, Boivin G5.

Author information: 1 Research Center in Infectious Diseases of the CHU of Québec and Laval University, 2705, Boul. Laurier (RC-709), Québec City, QC G1V 4G2, Canada. mariana.baz@crchudequebec.ulaval.ca. 2 Research Center in Infectious Diseases of the CHU of Québec and Laval University, 2705, Boul. Laurier (RC-709), Québec City, QC G1V 4G2, Canada. julie.carbonneau@crchudequebec.ulaval.ca. 3 Research Center in Infectious Diseases of the CHU of Québec and Laval University, 2705, Boul. Laurier (RC-709), Québec City, QC G1V 4G2, Canada. rheaumec@hotmail.com. 4 Research Center in Infectious Diseases of the CHU of Québec and Laval University, 2705, Boul. Laurier (RC-709), Québec City, QC G1V 4G2, Canada. Marieelene.Cavanagh@crchudequebec.ulaval.ca.  5 Research Center in Infectious Diseases of the CHU of Québec and Laval University, 2705, Boul. Laurier (RC-709), Québec City, QC G1V 4G2, Canada. Guy.Boivin@crchul.ulaval.ca.

 

Abstract

Immunosuppressed individuals can shed influenza virus for prolonged periods of time, leading to the frequent emergence of antiviral resistance. We evaluated the benefits of oseltamivir and favipiravir combination therapy compared to single antiviral agents and monitored the emergence of drug-resistant variants in a pharmacologically immunosuppressed mouse model infected with the A(H1N1) pandemic influenza virus. C57BL/6 mice were immunosuppressed with cyclophosphamide and infected with a lethal dose of pandemic influenza A(H1N1) virus. Forty-eight hours post-infection, mice were treated with oseltamivir (20 mg/kg), favipiravir (20 or 50 mg/kg) or both agents BID for 5 or 10 days. Body weight losses, survival rates, lung viral titers, cytokine levels and emergence of resistant viruses were evaluated. Treatment of immunosuppressed mice with high (50 mg/kg) but not low (20 mg/kg) doses of favipiravir in combination with oseltamivir (20 mg/kg) significantly delayed mortality and reduced lung viral titers compared to treatment with a single drug regimen with oseltamivir but did not prevent the emergence of oseltamivir-resistant H275Y neuraminidase variants. Combination therapy with oseltamivir and favipiravir should be considered for evaluation in clinical trials.

KEYWORDS: combination therapy; favipiravir; immunosuppression; mice; oseltamivir; pandemic influenza virus; resistance

PMID: 30400276 DOI: 10.3390/v10110610

Keywords: Influenza A; H1N1pdm09; Antivirals; Drugs Resistance; Oseltamivir; Favipiravir; Animal models.

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#Favipiravir inhibits in vitro #Usutu virus replication and delays disease progression in an #infection model in mice (Antiviral Res., abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

Antiviral Res. 2018 Oct 29. pii: S0166-3542(18)30467-4. doi: 10.1016/j.antiviral.2018.10.026. [Epub ahead of print]

Favipiravir inhibits in vitro Usutu virus replication and delays disease progression in an infection model in mice.

Segura Guerrero NA1, Sharma S2, Neyts J3, Kaptein SJF2.

Author information: 1 KU Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, Leuven, Belgium; Universidad Pedagógica y Tecnológica de Colombia, Tunja, Colombia. 2 KU Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, Leuven, Belgium. 3 KU Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, Leuven, Belgium. Electronic address: johan.neyts@kuleuven.be.

 

Abstract

Usutu virus (USUV) is an emerging flavivirus that causes Usutu disease mainly in birds, but infection of mammals such as rodents, bats and horses has also been demonstrated. In addition, human cases (both in immunocompromised and -competent individuals) were also reported. Large outbreaks with other flaviviruses, such as West Nile virus and Zika virus, indicate that one should be vigilant for yet other outbreaks. To allow the identification of inhibitors of USUV replication, we established in vitro antiviral assays, which were validated using a small selection of known flavivirus inhibitors, including the broad-spectrum viral RNA polymerase inhibitor favipiravir (T-705). Next, an USUV infection model in AG129 (IFN-α/β and IFN-γ receptor knockout) mice was established. AG129 mice proved highly susceptible to USUV; an inoculum as low as 102 PFU (1.3 × 105 TCID50) resulted in the development of symptoms as early as 3 days post infection with viral RNA being detectable in various tissues. Treatment of mice with favipiravir (150 mg/kg/dose, BID, oral gavage) significantly reduced viral load in blood and tissues and significantly delayed virus-induced disease. This USUV mouse model is thus amenable for assessing the potential in vivo efficacy of (novel) USUV/flavivirus inhibitors.

KEYWORDS: AG129 mice; Antivirals; Emerging flavivirus; Mouse model; Usutu virus

PMID: 30385306 DOI: 10.1016/j.antiviral.2018.10.026

Keywords: Flavivirus; Usutu virus; Antivirals; Favipiravir; Animal models.

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Determining the #Mutation Bias of #Favipiravir in #Influenza Using Next-generation #Sequencing (J Virol., abstract)

[Source: Journal of Virology, full page: (LINK). Abstract, edited.]

Determining the Mutation Bias of Favipiravir in Influenza Using Next-generation Sequencing

Daniel H. Goldhill, Pinky Langat, Hongyao Xie, Monica Galiano, Shahjahan Miah, Paul Kellam, Maria Zambon, Angie Lackenby, Wendy Barclay

DOI: 10.1128/JVI.01217-18

 

ABSTRACT

Favipiravir is a broad-spectrum antiviral drug that may be used to treat influenza. Previous research has identified that favipiravir likely acts as a mutagen but the precise mutation bias that favipiravir induces in influenza virus RNAs has not been described. Here, we use next-generation sequencing (NGS) with barcoding of individual RNA molecules to accurately and quantitatively detect favipiravir-induced mutations and to sample orders of magnitude more mutations than would be possible through Sanger sequencing. We demonstrate that favipiravir causes mutations and show that favipiravir primarily acts as a guanine analogue and secondarily as an adenine analogue resulting in the accumulation of transition mutations. We also use a standard NGS pipeline to show that the mutagenic effect of favipiravir can be measured by whole genome sequencing of virus.

 

IMPORTANCE

New antiviral drugs are needed as a first line of defence in the event of a novel influenza pandemic. Favipiravir is a broad-spectrum antiviral which is effective against influenza. The exact mechanism of how favipiravir works to inhibit influenza is still unclear. We used next-generation sequencing (NGS) to demonstrate that favipiravir causes mutations in influenza RNA. The greater depth of NGS sequence information over traditional sequencing methods allowed us to precisely determine the bias of particular mutations caused by favipiravir. NGS can also be used in a standard diagnostic pipeline to show that favipiravir is acting on the virus by revealing the mutation bias pattern typical to the drug. Our work will aid in testing whether viruses are resistant to favipiravir and may help demonstrate the effect of favipiravir on viruses in a clinical setting. This will be important if favipiravir is used during a future influenza pandemic.

Copyright © 2018 Goldhill et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license.

Keywords: Influenza A; Antivirals; Drugs Resistance; Favipiravir.

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