Identification of GS 4104 as an Orally Bioavailable Prodrug of the Influenza Virus Neuraminidase Inhibitor GS 4071

ABSTRACT GS 4071 is a potent carbocyclic transition-state analog inhibitor of influenza virus neuraminidase with activity against both influenza A and B viruses in vitro. GS 4116, the guanidino analog of GS 4071, is a 10-fold more potent inhibitor of influenza virus replication in tissue culture than GS 4071. In this study we determined the oral bioavailabilities of GS 4071, GS 4116, and their respective ethyl ester prodrugs in rats. Both parent compounds and the prodrug of the guanidino analog exhibited poor oral bioavailability (2 to 4%) and low peak concentrations in plasma (C maxs; C max<0.06 μg/ml). In contrast, GS 4104, the ethyl ester prodrug of GS 4071, exhibited good oral bioavailability (35%) as GS 4071 and high C maxs of GS 4071 (Cmax = 0.47 μg/ml) which are 150 times the concentration necessary to inhibit influenza virus neuraminidase activity by 90%. The bioavailability of GS 4104 as GS 4071 was also determined in mice (30%), ferrets (11%), and dogs (73%). The plasma of all four species exhibited high, sustained concentrations of GS 4071 such that at 12 h postdosing the concentrations of GS 4071 in plasma exceeded those necessary to inhibit influenza virus neuraminidase activity by 90%. These results demonstrate that GS 4104 is an orally bioavailable prodrug of GS 4071 in animals and that it has the potential to be an oral agent for the prevention and treatment of influenza A and B virus infections in humans.

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Potent and Long-Acting Dimeric Inhibitors of Influenza Virus Neuraminidase Are Effective at a Once-Weekly Dosing Regimen

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.48.12.4542-4549.2004 ◽

2004 ◽

Vol 48 (12) ◽

pp. 4542-4549 ◽

Cited By ~ 56

Author(s):

Simon J. F. Macdonald ◽

Keith G. Watson ◽

Rachel Cameron ◽

David K. Chalmers ◽

Derek A. Demaine ◽

...

Keyword(s):

Influenza Virus ◽

Low Dose ◽

Neuraminidase Inhibitor ◽

Virus Infections ◽

Dosing Regimen ◽

Influenza Virus Replication ◽

Long Acting ◽

Influenza Virus Neuraminidase

ABSTRACT Dimeric derivatives (compounds 7 to 9) of the influenza virus neuraminidase inhibitor zanamivir (compound 2), which have linking groups of 14 to 18 atoms in length, are approximately 100-fold more potent inhibitors of influenza virus replication in vitro and in vivo than zanamivir. The observed optimum linker length of 18 to 22 Å, together with observations that the dimers cause aggregation of isolated neuraminidase tetramers and whole virus, indicate that the dimers benefit from multivalent binding via intertetramer and intervirion linkages. The outstanding long-lasting protective activities shown by compounds 8 and 9 in mouse influenza infectivity experiments and the extremely long residence times observed in the lungs of rats suggest that a single low dose of a dimer would provide effective treatment and prophylaxis for influenza virus infections.

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In Vitro and In Vivo Activities of Anti-Influenza Virus Compound T-705

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.46.4.977-981.2002 ◽

2002 ◽

Vol 46 (4) ◽

pp. 977-981 ◽

Cited By ~ 280

Author(s):

Y. Furuta ◽

K. Takahashi ◽

Y. Fukuda ◽

M. Kuno ◽

T. Kamiyama ◽

...

Keyword(s):

Influenza Virus ◽

Inhibitory Activity ◽

Influenza A ◽

Rna Viruses ◽

Neuraminidase Inhibitor ◽

Virus Infections ◽

Dna Viruses ◽

Virus Rna

ABSTRACT T-705 (6-fluoro-3-hydroxy-2-pyrazinecarboxamide) has been found to have potent and selective inhibitory activity against influenza virus. In an in vitro plaque reduction assay, T-705 showed potent inhibitory activity against influenza A, B, and C viruses, with 50% inhibitory concentrations (IC50s) of 0.013 to 0.48 μg/ml, while it showed no cytotoxicity at concentrations up to 1,000 μg/ml in Madin-Darby canine kidney cells. The selectivity index for influenza virus was more than 2,000. It was also active against a neuraminidase inhibitor-resistant virus and some amantadine-resistant viruses. T-705 showed weak activity against non-influenza virus RNA viruses, with the IC50s being higher for non-influenza virus RNA viruses than for influenza virus, and it had no activity against DNA viruses. Orally administered T-705 at 100 mg/kg of body weight/day (four times a day) for 5 days significantly reduced the mean pulmonary virus yields and the rate of mortality in mice infected with influenza virus A/PR/8/34 (3 × 102 PFU). These results suggest that T-705 may be a compound that is useful and highly selective against influenza virus infections and that has a mode of action different from those of commercially available drugs, such as amantadine, rimantadine, and neuraminidase inhibitors.

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In Vivo Influenza Virus-Inhibitory Effects of the Cyclopentane Neuraminidase Inhibitor RWJ-270201

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.45.3.749-757.2001 ◽

2001 ◽

Vol 45 (3) ◽

pp. 749-757 ◽

Cited By ~ 77

Author(s):

Robert W. Sidwell ◽

Donald F. Smee ◽

John H. Huffman ◽

Dale L. Barnard ◽

Kevin W. Bailey ◽

...

Keyword(s):

Influenza Virus ◽

Hong Kong ◽

Influenza A ◽

Arterial Oxygen Saturation ◽

Virus Titer ◽

Neuraminidase Inhibitor ◽

Arterial Oxygen ◽

Virus Infections ◽

Inhibitory Effects ◽

Lung Consolidation

ABSTRACT The cyclopentane influenza virus neuraminidase inhibitor RWJ-270201 was evaluated against influenza A/NWS/33 (H1N1), A/Shangdong/09/93 (H3N2), A/Victoria/3/75 (H3N2), and B/Hong Kong/05/72 virus infections in mice. Treatment was by oral gavage twice daily for 5 days beginning 4 h pre-virus exposure. The influenza virus inhibitor oseltamivir was run in parallel, and ribavirin was included in studies with the A/Shangdong and B/Hong Kong viruses. RWJ-270201 was inhibitory to all infections using doses as low as 1 mg/kg/day. Oseltamivir was generally up to 10-fold less effective than RWJ-270201. Ribavirin was also inhibitory but was less tolerated by the mice at the 75-mg/kg/day dose used. Disease-inhibitory effects included prevention of death, lessening of decline of arterial oxygen saturation, inhibition of lung consolidation, and reduction in lung virus titers. RWJ-270201 and oseltamivir, at doses of 10 and 1 mg/kg/day each, were compared with regard to their effects on daily lung parameters in influenza A/Shangdong/09/93 virus-infected mice. Maximum virus titer inhibition was seen on day 1, with RWJ-270201 exhibiting the greater inhibitory effect, a titer reduction of >104 cell culture 50% infective doses (CCID50)/g. By day 8, the lung virus titers in mice treated with RWJ-270201 had declined to 101.2 CCID50/g, whereas titers from oseltamivir-treated animals were >103CCID50/g. Mean lung consolidation was also higher in the oseltamivir-treated animals on day 8. Both neuraminidase inhibitors were well tolerated by the mice. RWJ-270201 was nontoxic at doses as high as 1,000 mg/kg/day. These data indicate potential for the oral use of RWJ-270201 in the treatment of influenza virus infections in humans.

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Penetration of GS4071, a novel influenza neuraminidase inhibitor, into rat bronchoalveolar lining fluid following oral administration of the prodrug GS4104.

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.41.9.1949 ◽

1997 ◽

Vol 41 (9) ◽

pp. 1949-1952 ◽

Cited By ~ 59

Author(s):

E J Eisenberg ◽

A Bidgood ◽

K C Cundy

Keyword(s):

Oral Administration ◽

Oral Bioavailability ◽

Influenza A ◽

Area Under The Curve ◽

Parent Drug ◽

Neuraminidase Inhibitor ◽

Virus Infections ◽

Important Indicator ◽

Potential Efficacy ◽

Plasma Peak

GS4071 is a novel potent inhibitor of influenza neuraminidase (Ki < 1 nM) with low (< 5%) oral bioavailability in animals. An ethyl ester prodrug of GS4071, GS4104, has exhibited good oral bioavailability in rat, mouse, and dog models and is currently being developed for the treatment of influenza A and B virus infections. Since influenza virus replicates primarily in the surface epithelial cells of the respiratory tract, the ability of the prodrug to deliver GS4071 to the bronchoalveolar lining fluid (BALF) following an oral dose of GS4104 should be an important indicator of its potential efficacy. In the present study, we determined the concentration-time profiles of GS4071 in the BALF and plasma of rats following oral administration of GS4104. The BALF was sampled by bronchoalveolar lavage with endogenous urea as a dilution marker. The concentration of GS4071 in BALF reached a peak at 2 h (1 h after the plasma peak) and declined at a slower rate than plasma levels, suggesting slow clearance of drug from the lung acini. The ratios of the area-under-the-curve (AUC) values of GS4071 in BALF to those in plasma were 1.05 for AUC from 0 to 6 h (AUC(0-6)) and 1.51 for AUC(0-infinity), indicating significant penetration of the parent drug into the lower respiratory tracts of rats following oral administration of the prodrug. No unchanged GS4104 was detected in BALF.

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The mechanism of resistance to favipiravir in influenza

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1811345115 ◽

2018 ◽

Vol 115 (45) ◽

pp. 11613-11618 ◽

Cited By ~ 87

Author(s):

Daniel H. Goldhill ◽

Aartjan J. W. te Velthuis ◽

Robert A. Fletcher ◽

Pinky Langat ◽

Maria Zambon ◽

...

Keyword(s):

Influenza Virus ◽

Influenza A Virus ◽

Influenza A ◽

H1n1 Influenza ◽

Viral Fitness ◽

Virus Infections ◽

Virus Rna ◽

Evolution Of Resistance ◽

Emergence Of Resistance

Favipiravir is a broad-spectrum antiviral that has shown promise in treatment of influenza virus infections. While emergence of resistance has been observed for many antiinfluenza drugs, to date, clinical trials and laboratory studies of favipiravir have not yielded resistant viruses. Here we show evolution of resistance to favipiravir in the pandemic H1N1 influenza A virus in a laboratory setting. We found that two mutations were required for robust resistance to favipiravir. We demonstrate that a K229R mutation in motif F of the PB1 subunit of the influenza virus RNA-dependent RNA polymerase (RdRP) confers resistance to favipiravir in vitro and in cell culture. This mutation has a cost to viral fitness, but fitness can be restored by a P653L mutation in the PA subunit of the polymerase. K229R also conferred favipiravir resistance to RNA polymerases of other influenza A virus strains, and its location within a highly conserved structural feature of the RdRP suggests that other RNA viruses might also acquire resistance through mutations in motif F. The mutations identified here could be used to screen influenza virus-infected patients treated with favipiravir for the emergence of resistance.

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Protective Role of Combined Polyphenols and Micronutrients against Influenza A Virus and SARS-CoV-2 Infection In Vitro

Biomedicines ◽

10.3390/biomedicines9111721 ◽

2021 ◽

Vol 9 (11) ◽

pp. 1721

Author(s):

Marta De Angelis ◽

David Della-Morte ◽

Gabriele Buttinelli ◽

Angela Di Martino ◽

Francesca Pacifici ◽

...

Keyword(s):

Influenza Virus ◽

Influenza A ◽

Viral Proteins ◽

Antiviral Effect ◽

Inhibitory Effect ◽

Protective Role ◽

Virus Infections ◽

Infected Cells ◽

Respiratory Virus Infections

Polyphenols have been widely studied for their antiviral effect against respiratory virus infections. Among these, resveratrol (RV) has been demonstrated to inhibit influenza virus replication and more recently, it has been tested together with pterostilbene against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In the present work, we evaluated the antiviral activity of polydatin, an RV precursor, and a mixture of polyphenols and other micronutrients, named A5+, against influenza virus and SARS-CoV-2 infections. To this end, we infected Vero E6 cells and analyzed the replication of both respiratory viruses in terms of viral proteins synthesis and viral titration. We demonstrated that A5+ showed a higher efficacy in inhibiting both influenza virus and SARS-CoV-2 infections compared to polydatin treatment alone. Indeed, post infection treatment significantly decreased viral proteins expression and viral release, probably by interfering with any step of virus replicative cycle. Intriguingly, A5+ treatment strongly reduced IL-6 cytokine production in influenza virus-infected cells, suggesting its potential anti-inflammatory properties during the infection. Overall, these results demonstrate the synergic and innovative antiviral efficacy of A5+ mixture, although further studies are needed to clarify the mechanisms underlying its inhibitory effect.

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In Vitro System for Modeling Influenza A Virus Resistance under Drug Pressure

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01385-09 ◽

2010 ◽

Vol 54 (8) ◽

pp. 3442-3450 ◽

Cited By ~ 19

Author(s):

Ashley N. Brown ◽

James J. McSharry ◽

Qingmei Weng ◽

Elizabeth M. Driebe ◽

David M. Engelthaler ◽

...

Keyword(s):

Influenza Virus ◽

Influenza A Virus ◽

Virus Replication ◽

Influenza A ◽

Mdck Cells ◽

Influenza Virus Infection ◽

Infection Model ◽

Virus Infections ◽

Drug Pressure

ABSTRACT One of the biggest challenges in the effort to treat and contain influenza A virus infections is the emergence of resistance during treatment. It is well documented that resistance to amantadine arises rapidly during the course of treatment due to mutations in the gene coding for the M2 protein. To address this problem, it is critical to develop experimental systems that can accurately model the selection of resistance under drug pressure as seen in humans. We used the hollow-fiber infection model (HFIM) system to examine the effect of amantadine on the replication of influenza virus, A/Albany/1/98 (H3N2), grown in MDCK cells. At 24 and 48 h postinfection, virus replication was inhibited in a dose-dependent fashion. At 72 and 96 h postinfection, virus replication was no longer inhibited, suggesting the emergence of amantadine-resistant virus. Sequencing of the M2 gene revealed that mutations appeared at between 48 and 72 h of drug treatment and that the mutations were identical to those identified in the clinic for amantadine-resistant viruses (e.g., V27A, A30T, and S31N). Interestingly, we found that the type of mutation was strongly affected by the dose of the drug. The data suggest that the HFIM is a good model for influenza virus infection and resistance generation in humans. The HFIM has the advantage of being a highly controlled system where multiplicity parameters can be directly and accurately controlled and measured.

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Characterization of Drug-Resistant Influenza Virus A(H1N1) and A(H3N2) Variants SelectedIn Vitrowith Laninamivir

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.03313-14 ◽

2014 ◽

Vol 58 (9) ◽

pp. 5220-5228 ◽

Cited By ~ 29

Author(s):

Mélanie Samson ◽

Yacine Abed ◽

François-Marc Desrochers ◽

Stephanie Hamilton ◽

Angela Luttick ◽

...

Keyword(s):

Influenza Virus ◽

Influenza A ◽

Solomon Islands ◽

The United States ◽

Drug Resistant ◽

Virus Infections ◽

Influenza A Viruses ◽

Oseltamivir Resistance ◽

Susceptibility Profiles

ABSTRACTNeuraminidase inhibitors (NAIs) play a major role for managing influenza virus infections. The widespread oseltamivir resistance among 2007-2008 seasonal A(H1N1) viruses and community outbreaks of oseltamivir-resistant A(H1N1)pdm09 strains highlights the need for additional anti-influenza virus agents. Laninamivir is a novel long-lasting NAI that has demonstratedin vitroactivity against influenza A and B viruses, and its prodrug (laninamivir octanoate) is in phase II clinical trials in the United States and other countries. Currently, little information is available on the mechanisms of resistance to laninamivir. In this study, we first performed neuraminidase (NA) inhibition assays to determine the activity of laninamivir against a set of influenza A viruses containing NA mutations conferring resistance to one or many other NAIs. We also generated drug-resistant A(H1N1) and A(H3N2) viruses underin vitrolaninamivir pressure. Laninamivir demonstrated a profile of susceptibility that was similar to that of zanamivir. More specifically, it retained activity against oseltamivir-resistant H275Y and N295S A(H1N1) variants and the E119V A(H3N2) variant.In vitro, laninamivir pressure selected the E119A NA substitution in the A/Solomon Islands/3/2006 A(H1N1) background, whereas E119K and G147E NA changes along with a K133E hemagglutinin (HA) substitution were selected in the A/Quebec/144147/2009 A(H1N1)pdm09 strain. In the A/Brisbane/10/2007 A(H3N2) background, a large NA deletion accompanied by S138A/P194L HA substitutions was selected. This H3N2 variant had altered receptor-binding properties and was highly resistant to laninamivir in plaque reduction assays. Overall, we confirmed the similarity between zanamivir and laninamivir susceptibility profiles and demonstrated that both NA and HA changes can contribute to laninamivir resistancein vitro.

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Ethanol Extract of Caesalpinia decapetala Inhibits Influenza Virus Infection In Vitro and In Vivo

Viruses ◽

10.3390/v12050557 ◽

2020 ◽

Vol 12 (5) ◽

pp. 557 ◽

Cited By ~ 1

Author(s):

Li Zhang ◽

Jungang Chen ◽

Chang Ke ◽

Haiwei Zhang ◽

Shoujun Zhang ◽

...

Keyword(s):

Influenza Virus ◽

Influenza A ◽

Antiviral Agents ◽

Influenza Virus Infection ◽

Virus Titer ◽

Ethanol Extract ◽

Influenza Viruses ◽

Virus Infections

Influenza virus infections can lead to viral pneumonia and acute respiratory distress syndrome in severe cases, causing significant morbidity and mortality and posing a great threat to human health. Because of the diversity of influenza virus strains and drug resistance to the current direct antiviral agents, there have been no effective drugs as yet to cure all patients infected by influenza viruses. Natural products from plants contain compounds with diverse structures that have the potential to interact with multiple host and virus factors. In this study, we identified the ethanol extract of Caesalpinia decapetala (Roth) Alston (EEC) as an inhibitor against the replication of a panel of influenza A and B viruses both on human pulmonary epithelial A549 and human monocytic U937 cells. The animal study revealed that EEC administration reduces the weight loss and improves the survival rate of mice infected with lethal influenza virus. Also, EEC treatment attenuated lung injury and reduced virus titer significantly. In conclusion, we showed that EEC has antiviral activity both in vitro and in vivo, suggesting that the plant C. decapetala has the potential to be further developed as a resource of new anti-influenza drugs.

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