Cryptoporic acid E from Cryptoporus volvatus inhibits influenza virus replication in vitro

ABSTRACT The mechanisms regulating the synthesis of mRNA, cRNA, and viral genomic RNA (vRNA) by the influenza A virus RNA-dependent RNA polymerase are not fully understood. Previous studies in our laboratory have shown that virion-derived viral ribonucleoprotein complexes synthesize both mRNA and cRNA in vitro and early in the infection cycle in vivo. Our continued studies showed that de novo synthesis of cRNA in vitro is more sensitive to the concentrations of ATP, CTP, and GTP than capped-primer-dependent synthesis of mRNA. Using rescued recombinant influenza A/WSN/33 viruses, we now demonstrate that the 3′-terminal sequence of the vRNA promoter dictates the requirement for a high nucleoside triphosphate (NTP) concentration during de novo-initiated replication to cRNA, whereas this is not the case for the extension of capped primers during transcription to mRNA. In contrast to some other viral polymerases, for which only the initiating NTP is required at high concentrations, influenza virus polymerase requires high concentrations of the first three NTPs. In addition, we show that base pair mutations in the vRNA promoter can lead to nontemplated dead-end mutations during replication to cRNA in vivo. Based on our observations, we propose a new model for the de novo initiation of influenza virus replication.

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Comparison of influenza virus replication fidelity in vitro using selection pressure with monoclonal antibodies

Journal of Medical Virology ◽

10.1002/jmv.23532 ◽

2013 ◽

Vol 85 (6) ◽

pp. 1090-1094 ◽

Cited By ~ 2

Author(s):

Karen Ka Yin Wong ◽

Steve Rockman ◽

Chi Ong ◽

Rowena Bull ◽

Sacha Stelzer-Braid ◽

...

Keyword(s):

Influenza Virus ◽

Monoclonal Antibodies ◽

Virus Replication ◽

Selection Pressure ◽

Replication Fidelity ◽

Influenza Virus Replication

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Cryptoporus volvatus Extract Inhibits Influenza Virus Replication In Vitro and In Vivo

PLoS ONE ◽

10.1371/journal.pone.0113604 ◽

2014 ◽

Vol 9 (12) ◽

pp. e113604 ◽

Cited By ~ 12

Author(s):

Li Gao ◽

Yipeng Sun ◽

Jianyong Si ◽

Jinhua Liu ◽

Guibo Sun ◽

...

Keyword(s):

Influenza Virus ◽

Virus Replication ◽

Influenza Virus Replication

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In Vitro Characterization of A-315675, a Highly Potent Inhibitor of A and B Strain Influenza Virus Neuraminidases and Influenza Virus Replication

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.46.4.1014-1021.2002 ◽

2002 ◽

Vol 46 (4) ◽

pp. 1014-1021 ◽

Cited By ~ 78

Author(s):

Warren M. Kati ◽

Debra Montgomery ◽

Robert Carrick ◽

Larisa Gubareva ◽

Clarence Maring ◽

...

Keyword(s):

Cell Culture ◽

Influenza Virus ◽

Virus Replication ◽

Influenza A ◽

Strong Support ◽

Oseltamivir Carboxylate ◽

Influenza Virus Replication ◽

H3n2 Influenza ◽

H3n2 Influenza Virus

ABSTRACT A-315675 is a novel, pyrrolidine-based compound that was evaluated in this study for its ability to inhibit A and B strain influenza virus neuraminidases in enzyme assays and influenza virus replication in cell culture. A-315675 effectively inhibited influenza A N1, N2, and N9 and B strain neuraminidases with inhibitor constant (Ki ) values between 0.024 and 0.31 nM. These values were comparable to or lower than the Ki values measured for oseltamivir carboxylate (GS4071), zanamivir, and BCX-1812, except for the N1 enzymes that were found to be the most sensitive to BCX-1812. The time-dependent inhibition of neuraminidase catalytic activity observed with A-315675 is likely due to its very low rate of dissociation from the active site of neuraminidase. The half times for dissociation of A-315675 from B/Memphis/3/89 and A/Tokyo/3/67 (H3N2) influenza virus neuraminidases of 10 to 12 h are significantly slower than the half times measured for oseltamivir carboxylate (33 to 60 min). A-315675 inhibited the replication of several laboratory strains of influenza virus in cell culture with potencies that were comparable or superior to those for oseltamivir carboxylate and BCX-1812, except for the A/H1N1 viruses that were found to be two- to fourfold more susceptible to BCX-1812. A-315675 and oseltamivir carboxylate exhibited comparable potencies against a panel of A/H1N1 and A/H3N2 influenza virus clinical isolates, but A-315675 was found to be significantly more potent than oseltamivir carboxylate against the B strain isolates. The favorable in vitro results relative to other clinically effective agents provide strong support for the further investigation of A-315675 as a potential therapy for influenza virus infections.

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Drug repositioning of Clopidogrel or Triamterene to inhibit influenza virus replication in vitro

PLoS ONE ◽

10.1371/journal.pone.0259129 ◽

2021 ◽

Vol 16 (10) ◽

pp. e0259129

Author(s):

Nichole Orr-Burks ◽

Jackelyn Murray ◽

Kyle V. Todd ◽

Abhijeet Bakre ◽

Ralph A. Tripp

Keyword(s):

Influenza Virus ◽

Virus Replication ◽

Drug Repositioning ◽

Antiviral Drug ◽

Influenza Viruses ◽

Influenza Virus Replication ◽

Approved Drugs ◽

Multiple Strains ◽

Tract Infections

Influenza viruses cause respiratory tract infections and substantial health concerns. Infection may result in mild to severe respiratory disease associated with morbidity and some mortality. Several anti-influenza drugs are available, but these agents target viral components and are susceptible to drug resistance. There is a need for new antiviral drug strategies that include repurposing of clinically approved drugs. Drugs that target cellular machinery necessary for influenza virus replication can provide a means for inhibiting influenza virus replication. We used RNA interference screening to identify key host cell genes required for influenza replication, and then FDA-approved drugs that could be repurposed for targeting host genes. We examined the effects of Clopidogrel and Triamterene to inhibit A/WSN/33 (EC50 5.84 uM and 31.48 uM, respectively), A/CA/04/09 (EC50 6.432 uM and 3.32 uM, respectively), and B/Yamagata/16/1988 (EC50 0.28 uM and 0.11 uM, respectively) replication. Clopidogrel and Triamterene provide a druggable approach to influenza treatment across multiple strains and subtypes.

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Comparative in vitro analysis of inhibition of rhinovirus and influenza virus replication by mucoactive secretolytic agents and plant extracts

BMC Complementary Medicine and Therapies ◽

10.1186/s12906-020-03173-2 ◽

2020 ◽

Vol 20 (1) ◽

Author(s):

Christin Walther ◽

Kristin Döring ◽

Michaela Schmidtke

Keyword(s):

Influenza Virus ◽

Virus Replication ◽

Cytopathic Effect ◽

Respiratory Infections ◽

Mdck Cells ◽

Acute Respiratory Infections ◽

Over The Counter ◽

Influenza Virus Replication ◽

Acetyl Cysteine

Abstract Background Rhinoviruses and influenza viruses cause millions of acute respiratory infections annually. Symptoms of mild acute respiratory infections are commonly treated with over-the-counter products like ambroxol, bromhexine, and N-acetyl cysteine, as well as of thyme and pelargonium extracts today. Because the direct antiviral activity of these over-the-counter products has not been studied in a systematic way, the current study aimed to compare their inhibitory effect against rhinovirus and influenza virus replication in an in vitro setting. Methods The cytotoxicity of ambroxol, bromhexine, and N-acetyl cysteine, as well as of thyme and pelargonium extracts was analyzed in Madin Darby canine kidney (MDCK) and HeLa Ohio cells. The antiviral effect of these over-the-counter products was compared by analyzing the dose-dependent inhibition (i) of rhinovirus A2- and B14-induced cytopathic effect in HeLa Ohio cells and (ii) of influenza virus A/Hong Kong/68 (subtype H3N2)- and A/Jena/8178/09 (subtype H1N1, pandemic)-induced cytopathic effect in MDCK cells at non-cytotoxic concentrations. To get insights into the mechanism of action of pelargonium extract against influenza virus, we performed time-of-addition assays as well as hemagglutination and neuraminidase inhibition assays. Results N-acetyl cysteine, thyme and pelargonium extract showed no or only marginal cytotoxicity in MDCK and HeLa Ohio cells in the tested concentration range. The 50% cytotoxic concentration of ambroxol and bromhexine was 51.85 and 61.24 μM, respectively. No anti-rhinoviral activity was detected at non-cytotoxic concentrations in this in vitro study setting. Ambroxol, bromhexine, and N-acetyl cysteine inhibited the influenza virus-induced cytopathic effect in MDCK cells no or less than 50%. In contrast, a dose-dependent anti-influenza virus activity of thyme and pelargonium extracts was demonstrated. The time-of addition assays revealed an inhibition of early and late steps of influenza virus replication by pelargonium extract whereas zanamivir acted on late steps only. The proven block of viral neuraminidase activity might explain the inhibition of influenza virus replication when added after viral adsorption. Conclusion The study results indicate a distinct inhibition of influenza A virus replication by thyme and pelargonium extract which might contribute to the beneficial effects of these plant extracts on acute respiratory infections symptoms.

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