Effects of the Combination of Favipiravir (T-705) and Oseltamivir on Influenza A Virus Infections in Mice

Smee, Donald F.; Hurst, Brett L.; Wong, Min-Hui; Bailey, Kevin W.; Tarbet, E. Bart; Morrey, John D.; Furuta, Yoshihiko

doi:10.1128/aac.00933-09

Cited by 100 publications

(95 citation statements)

References 30 publications

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“…Briefly, each lung was removed, weighed, and homogenized in minimal essential medium (MEM), and the viral titer was determined by the TCID 50 assay with MDCK cells. The number of wells showing a positive cytopathic effect was scored, and the titer (TCID 50 ) per milligram of lung tissue was calculated by standard procedures (28)(29)(30). All experimental procedures were approved by the Institutional Animal Care and Use Committee (IACUC) of Shantou University.…”

Section: Methodsmentioning

confidence: 99%

Identification of 23-( S )-2-Amino-3-Phenylpropanoyl-Silybin as an Antiviral Agent for Influenza A Virus Infection In Vitro and In Vivo

Dai

et al. 2013

Antimicrob Agents Chemother

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It has been reported that autophagy is involved in the replication of many viruses. In this study, we screened 89 medicinal plants, using an assay based on the inhibition of the formation of the Atg12-Atg5/Atg16 heterotrimer, an important regulator of autophagy, and selected Silybum marianum L. for further study. An antiviral assay indicated that silybin (S0), the major active compound of S. marianum L., can inhibit influenza A virus (IAV) infection. We later synthesized 5 silybin derivatives (S1 through S5) and found that 23-(S)-2-amino-3-phenylpropanoyl-silybin (S3) had the best activity. When we compared the polarities of the substituent groups, we found that the hydrophobicity of the substituent groups was positively correlated with their activities. We further studied the mechanisms of action of these compounds and determined that S0 and S3 also inhibited both the formation of the Atg12-Atg5/Atg16 heterotrimer and the elevated autophagy induced by IAV infection. In addition, we found that S0 and S3 could inhibit several components induced by IAV infection, including oxidative stress, the activation of extracellular signal-regulated kinase (ERK)/p38 mitogen-activated protein kinase (MAPK) and IB kinase (IKK) pathways, and the expression of autophagic genes, especially Atg7 and Atg3. All of these components have been reported to be related to the formation of the Atg12-Atg5/Atg16 heterotrimer, which might validate our screening strategy. Finally, we demonstrated that S3 can significantly reduce influenza virus replication and the associated mortality in infected mice. In conclusion, we identified 23-(S)-2-amino-3-phenylpropanoyl-silybin as a promising inhibitor of IAV infection.

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Section: Methodsmentioning

confidence: 99%

Identification of 23-( S )-2-Amino-3-Phenylpropanoyl-Silybin as an Antiviral Agent for Influenza A Virus Infection In Vitro and In Vivo

Dai

et al. 2013

Antimicrob Agents Chemother

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“…In addition, T-705 is less likely to allow virus regrowth after agent removal than a neuraminidase inhibitor. The combination therapy with a neuraminidase inhibitor has synergistic effects (6,12,13). Furthermore, no resistant virus developed until 30 passages were completed in the presence of various concentrations of T-705, which indicates that T-705 is unlikely to cause resistant viruses (4; unpublished data).…”

mentioning

confidence: 99%

Mechanism of Action of T-705 Ribosyl Triphosphate against Influenza Virus RNA Polymerase

Sangawa

Komeno

Nishikawa

et al. 2013

Antimicrob Agents Chemother

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170

152

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T-705 (favipiravir; 6-fluoro-3-hydroxy-2-pyrazinecarboxamide) selectively and strongly inhibits replication of the influenza virus in vitro and in vivo. T-705 has been shown to be converted to T-705-4-ribofuranosyl-5-triphosphate (T-705RTP) by intracellular enzymes and then functions as a nucleotide analog to selectively inhibit RNA-dependent RNA polymerase (RdRp) of the influenza virus. To elucidate these inhibitory mechanisms, we analyzed the enzyme kinetics of inhibition using Lineweaver-Burk plots of four natural nucleoside triphosphates and conducted polyacrylamide gel electrophoresis of the primer extension products initiated from 32 P-radiolabeled 5=Cap1 RNA. Enzyme kinetic analysis demonstrated that T-705RTP inhibited the incorporation of ATP and GTP in a competitive manner, which suggests that T-705RTP is recognized as a purine nucleotide by influenza virus RdRp and inhibited the incorporation of UTP and CTP in noncompetitive and mixed-type manners, respectively. Primer extension analysis demonstrated that a single molecule of T-705RTP was incorporated into the nascent RNA strand of the influenza virus and inhibited the subsequent incorporation of nucleotides. These results suggest that a single molecule of T-705RTP is incorporated into the nascent RNA strand as a purine nucleotide analog and inhibits strand extension, even though the natural ribose of T-705RTP has a 3=-OH group, which is essential for forming a covalent bond with the phosphate group.

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“…We have used this mouse-adapted strain of virus for other antiviral studies [21,[24][25][26]. The infectious virus inoculation of 10 2.5 CCID 50 per mouse equated to approximately 4 mouse 50% lethal doses.…”

Section: Antiviral Testing In Micementioning

confidence: 99%

Effects of TheraMax on Influenza Virus Infections in Cell Culture and in Mice

Smee

Hurst

Wong

2011

Antivir Chem Chemother

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Background: Limited in vivo studies in the scientific literature suggest that components of green tea and elderberry may be beneficial in treating influenza virus infections. They are thought to act by blocking virus adsorption to cells. TheraMax® is a proprietary medication administered by nasal spray that contains both green tea and elderberry extracts that was evaluated for antiviral activity. Methods: TheraMax was tested by dilution in Madin-Darby canine kidney cell cultures in standard viral cytopathic effect (CPE) inhibition and virucidal assays against eight influenza A and B strains. It was also administered intranasally to mice to determine protective activity compared to oral oseltamivir against an influenza A/NWS/33 (H1N1) infection. Results: In cell culture assays, TheraMax was found to inhibit viral CPE by 50% at a 1:20 dilution for seven of the eight virus strains, with no virucidal activity at 1:2 dilution. The undiluted product was administered to anaesthetized mice twice daily for 4 days starting 2 h before or 12 h after infection. Alternatively, TheraMax and virus were combined for treatment and infection. Oseltamivir was given orally twice daily for 5 days at 10 mg/kg/day starting at -2 h. TheraMax (combined directly with virus) and oseltamivir each prevented death and curtailed weight loss during the infection, and improved lung haemorrhage scores on day 6. TheraMax starting at -2 h or 12 h significantly delayed death by >2 days and reduced lung haemorrhage scores, but most animals died. Conclusions: These combined results indicate that TheraMax delayed symptoms during animal infections, likely through blocking of virus adsorption.

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Effects of the Combination of Favipiravir (T-705) and Oseltamivir on Influenza A Virus Infections in Mice

Cited by 100 publications

References 30 publications

Identification of 23-( S )-2-Amino-3-Phenylpropanoyl-Silybin as an Antiviral Agent for Influenza A Virus Infection In Vitro and In Vivo

Identification of 23-( S )-2-Amino-3-Phenylpropanoyl-Silybin as an Antiviral Agent for Influenza A Virus Infection In Vitro and In Vivo

Mechanism of Action of T-705 Ribosyl Triphosphate against Influenza Virus RNA Polymerase

Effects of TheraMax on Influenza Virus Infections in Cell Culture and in Mice

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