scholarly journals T-705 (Favipiravir) Inhibition of Arenavirus Replication in Cell Culture

2010 ◽  
Vol 55 (2) ◽  
pp. 782-787 ◽  
Author(s):  
Michelle Mendenhall ◽  
Andrew Russell ◽  
Terry Juelich ◽  
Emily L. Messina ◽  
Donald F. Smee ◽  
...  
Keyword(s):  
Cell Culture ◽  
Antiviral Activity ◽  
Viral Replication ◽  
Antiviral Agent ◽  
Febrile Illness ◽  
Hemorrhagic Fever ◽  
Intermediate Stage ◽  
Lymphocytic Choriomeningitis ◽  
Hamster Model ◽  
Highly Pathogenic

ABSTRACTA number of New World arenaviruses (Junín [JUNV], Machupo [MACV], and Guanarito [GTOV] viruses) can cause human disease ranging from mild febrile illness to a severe and often fatal hemorrhagic fever syndrome. These highly pathogenic viruses and the Old World Lassa fever virus pose a significant threat to public health and national security. The only licensed antiviral agent with activity against these viruses, ribavirin, has had mixed success in treating severe arenaviral disease and is associated with significant toxicities. A novel pyrazine derivative currently in clinical trials for the treatment of influenza virus infections, T-705 (favipiravir), has demonstrated broad-spectrum activity against a number of RNA viruses, including arenaviruses. T-705 has also been shown to be effective against Pichinde arenavirus infection in a hamster model. Here, we demonstrate the robust antiviral activity of T-705 against authentic highly pathogenic arenaviruses in cell culture. We show that T-705 disrupts an early or intermediate stage in viral replication, distinct from absorption or release, and that its antiviral activity in cell culture is reversed by the addition of purine bases and nucleosides, but not with pyrimidines. Specific inhibition of viral replication/transcription by T-705 was demonstrated using a lymphocytic choriomeningitis arenavirus replicon system. Our findings indicate that T-705 acts to inhibit arenavirus replication/transcription and may directly target the viral RNA-dependent RNA polymerase.

scholarly journals Activation of RNase L in Egyptian Rousette Bat-Derived RoNi/7 Cells Is Dependent Primarily on OAS3 and Independent of MAVS Signaling

mBio ◽  
2019 ◽  
Vol 10 (6) ◽  
Author(s):  
Yize Li ◽  
Beihua Dong ◽  
Zuzhang Wei ◽  
Robert H. Silverman ◽  
Susan R. Weiss
Keyword(s):  
Antiviral Activity ◽  
Viral Replication ◽  
Viral Infection ◽  
Rna Viruses ◽  
Primary Response ◽  
Human Cells ◽  
Secondary Effect ◽  
Rnase L ◽  
Interferon Signaling ◽  
Highly Pathogenic

ABSTRACT Bats are reservoirs for many RNA viruses that are highly pathogenic in humans yet relatively apathogenic in the natural host. It has been suggested that differences in innate immunity are responsible. The antiviral OAS-RNase L pathway is well characterized in humans, but there is little known about its activation and antiviral activity in bats. During infection, OASs, upon sensing double-stranded RNA (dsRNA), produce 2′-5′ oligoadenylates (2-5A), leading to activation of RNase L which degrades viral and host RNA, limiting viral replication. Humans encode three active OASs (OAS1 to -3). Analysis of the Egyptian Rousette bat genome combined with mRNA sequencing from bat RoNi/7 cells revealed three homologous OAS proteins. Interferon alpha treatment or viral infection induced all three OAS mRNAs, but RNase L mRNA is constitutively expressed. Sindbis virus (SINV) or vaccinia virus (VACVΔE3L) infection of wild-type (WT) or OAS1-KO (knockout), OAS2-KO, or MAVS-KO RoNi/7 cells, but not RNase L-KO or OAS3-KO cells, induces robust RNase L activation. SINV replication is 100- to 200-fold higher in the absence of RNase L or OAS3 than in WT cells. However, MAVS-KO had no detectable effect on RNA degradation or replication. Thus, in RoNi/7 bat cells, as in human cells, activation of RNase L during infection and its antiviral activity are dependent primarily on OAS3 while MAVS signaling is not required for the activation of RNase L and restriction of infection. Our findings indicate that OAS proteins serve as pattern recognition receptors (PRRs) to recognize viral dsRNA and that this pathway is a primary response to virus rather than a secondary effect of interferon signaling. IMPORTANCE Many RNA viruses that are highly pathogenic in humans are relatively apathogenic in their bat reservoirs, making it important to compare innate immune responses in bats to those well characterized in humans. One such antiviral response is the OAS-RNase L pathway. OASs, upon sensing dsRNA, produce 2-5A, leading to activation of RNase L which degrades viral and host RNA, limiting viral replication. Analysis of Egyptian Rousette bat sequences revealed three OAS genes expressing OAS1, OAS2, and OAS3 proteins. Interferon treatment or viral infection induces all three bat OAS mRNAs. In these bat cells as in human cells, RNase L activation and its antiviral activity are dependent primarily on OAS3 while MAVS signaling is not required. Importantly, our findings indicate the OAS-RNase L system is a primary response to virus rather than a secondary effect of interferon signaling and therefore can be activated early in infection or while interferon signaling is antagonized.

scholarly journals Identification of anti-severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) oxysterol derivatives in vitro

2021 ◽  
Author(s):  
Hirofumi Ohashi ◽  
Feng Wang ◽  
Frank Stappenbeck ◽  
Kana Tsuchimoto ◽  
Chisa Kobayashi ◽  
...  
Keyword(s):  
Cell Culture ◽  
Severe Acute Respiratory Syndrome ◽  
Antiviral Activity ◽  
Viral Replication ◽  
Cultured Cells ◽  
Plasma Concentrations ◽  
Hepatitis D ◽  
Infection Assay ◽  
Naturally Occurring ◽  
Increased Risk

AbstractDevelopment of effective antiviral drugs targeting the severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) are urgently needed to combat the coronavirus disease 2019 (COVID-19). Oxysterols, defined as oxidized derivatives of cholesterol, include endogenous (naturally occurring) cholesterol metabolites as well as semi-synthetic oxysterol derivatives. We have previously studied the use of semi-synthetic oxysterol derivatives as drug candidates for inhibition of cancer, fibrosis, and bone regeneration. In this study, we have screened a panel of naturally occurring and semi-synthetic oxysterol derivatives for anti-SARS-CoV-2 activity, using a cell culture infection assay. We show that the natural oxysterols, 7-ketocholesterol, 22(R)-hydroxycholesterol, 24(S)-hydroxycholesterol, and 27-hydroxycholesterol, substantially inhibited SARS-CoV-2 propagation in cultured cells. Among semi-synthetic oxysterols, Oxy186 displayed antiviral activity comparable to natural oxysterols. In addition, related oxysterol analogues Oxy210 and Oxy232 displayed more robust anti-SARS-CoV-2 activities, reducing viral replication more than 90% at 10 μM and 99% at 15 μM, respectively. When orally administered in mice, peak plasma concentrations of Oxy210 fall into a therapeutically relevant range (19 μM), based on the dose-dependent curve for antiviral activity in our cell culture infection assay. Mechanistic studies suggest that Oxy210 reduced replication of SARS-CoV-2 with disrupting the formation of double membrane vesicles (DMVs), intracellular membrane compartments associated with viral replication. Oxy210 also inhibited the replication of hepatitis C virus, another RNA virus whose replication is associated with DMVs, but not the replication of the DMV-independent hepatitis D virus. Our study warrants further evaluation of Oxy210 and Oxy232 as a safe and reliable oral medication, which could help protect vulnerable populations with increased risk developing COVID-19.

scholarly journals Identification of a Broad-Spectrum Arenavirus Entry Inhibitor

2008 ◽  
Vol 82 (21) ◽  
pp. 10768-10775 ◽  
Author(s):  
Ryan A. Larson ◽  
Dongcheng Dai ◽  
Virginia T. Hosack ◽  
Ying Tan ◽  
Tove’ C. Bolken ◽  
...  
Keyword(s):  
Antiviral Activity ◽  
Viral Entry ◽  
Transmembrane Domain ◽  
Benzimidazole Derivative ◽  
Genetic Selection ◽  
Hemorrhagic Fever ◽  
Lymphocytic Choriomeningitis ◽  
Site Directed Mutagenesis ◽  
Lassa Virus ◽  
Carboxy Terminal

ABSTRACT Several arenaviruses, including Lassa virus (LASV), are causative agents of hemorrhagic fever, for which effective therapeutic options are lacking. The LASV envelope glycoprotein (GP) gene was used to generate lentiviral pseudotypes to identify small-molecule inhibitors of viral entry. A benzimidazole derivative with potent antiviral activity was identified from a high-throughput screen utilizing this strategy. Subsequent lead optimization for antiviral activity identified a modified structure, ST-193, with a 50% inhibitory concentration (IC50) of 1.6 nM against LASV pseudotypes. ST-193 inhibited pseudotypes generated with other arenavirus envelopes as well, including the remaining four commonly associated with hemorrhagic fever (IC50s for Junín, Machupo, Guanarito, and Sabiá were in the 0.2 to 12 nM range) but exhibited no antiviral activity against pseudotypes incorporating either the GP from the LASV-related arenavirus lymphocytic choriomeningitis virus (LCMV) or the unrelated G protein from vesicular stomatitis virus, at concentrations of up to 10 μM. Determinants of ST-193 sensitivity were mapped through a combination of LASV-LCMV domain-swapping experiments, genetic selection of viral variants, and site-directed mutagenesis. Taken together, these studies demonstrate that sensitivity to ST-193 is dictated by a segment of about 30 amino acids within the GP2 subunit. This region includes the carboxy-terminal region of the ectodomain and the predicted transmembrane domain of the envelope protein, revealing a novel antiviral target within the arenavirus envelope GP.

scholarly journals Efficient incorporation and template-dependent polymerase inhibition are major determinants for the broad-spectrum antiviral activity of remdesivir

2021 ◽  
Author(s):  
Matthias Götte ◽  
Calvin J. Gordon ◽  
Hery W. Lee ◽  
Egor P. Tchesnokov ◽  
Jason K. Perry ◽  
...  
Keyword(s):  
Antiviral Activity ◽  
Broad Spectrum ◽  
Rna Viruses ◽  
Cyano Group ◽  
Nipah Virus ◽  
Antiviral Agent ◽  
Hemorrhagic Fever ◽  
Inhibitory Effects ◽  
Hemorrhagic Fever Virus ◽  
Negative Sense

Remdesivir (RDV) is a direct antiviral agent that is approved in several countries for the treatment of coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). RDV exhibits broad-spectrum antiviral activity against positive-sense RNA viruses, e.g., SARS-CoV-2 and hepatitis C virus (HCV) and non-segmented negative-sense RNA viruses, e.g., Nipah virus (NiV), while several segmented negative-sense RNA viruses such as influenza (Flu) virus or Crimean-Congo hemorrhagic fever virus (CCHFV) are not sensitive to the drug. The reasons for this apparent pattern are unknown. Here, we expressed and purified representative RNA-dependent RNA polymerases (RdRp) and studied three biochemical parameters that have been associated with the inhibitory effects of RDV-triphosphate (TP): (i) selective incorporation of the nucleotide substrate RDV-TP, (ii) the effect of the incorporated RDV-monophosphate (MP) on primer extension, and (iii) the effect of RDV-MP in the template during incorporation of the complementary UTP. The results of this study revealed a strong correlation between antiviral effects and efficient incorporation of RDV-TP. Delayed chain-termination is heterogeneous and usually inefficient at higher NTP concentrations. In contrast, template-dependent inhibition of UTP incorporation opposite the embedded RDV-MP is seen with all polymerases. Molecular modeling suggests a steric conflict between the 1′-cyano group of RDV-MP and conserved residues of RdRp motif F. We conclude that future efforts in the development of nucleotide analogues with a broader spectrum of antiviral activities should focus on improving rates of incorporation while capitalizing on the inhibitory effects of a bulky 1′-modification.

scholarly journals Validation of Inactivation Methods for Arenaviruses

Viruses ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 968
Author(s):  
Silke Olschewski ◽  
Anke Thielebein ◽  
Chris Hoffmann ◽  
Olivia Blake ◽  
Jonas Müller ◽  
...  
Keyword(s):  
Cell Culture ◽  
Hemorrhagic Fever ◽  
Downstream Processing ◽  
Cell Culture Supernatant ◽  
Lassa Virus ◽  
Highly Pathogenic ◽  
Cell Culture Systems ◽  
Pathogenic Viruses ◽  
Infected Cells ◽  
Biosafety Level

Several of the human-pathogenic arenaviruses cause hemorrhagic fever and have to be handled under biosafety level 4 conditions, including Lassa virus. Rapid and safe inactivation of specimens containing these viruses is fundamental to enable downstream processing for diagnostics or research under lower biosafety conditions. We established a protocol to test the efficacy of inactivation methods using the low-pathogenic Morogoro arenavirus as surrogate for the related highly pathogenic viruses. As the validation of chemical inactivation methods in cell culture systems is difficult due to cell toxicity of commonly used chemicals, we employed filter devices to remove the chemical and concentrate the virus after inactivation and before inoculation into cell culture. Viral replication in the cells was monitored over 4 weeks by using indirect immunofluorescence and immunofocus assay. The performance of the protocol was verified using published inactivation methods including chemicals and heat. Ten additional methods to inactivate virus in infected cells or cell culture supernatant were validated and shown to reduce virus titers to undetectable levels. In summary, we provide a robust protocol for the validation of chemical and physical inactivation of arenaviruses in cell culture, which can be readily adapted to different inactivation methods and specimen matrices.

scholarly journals The Bioactive Lipid 4-Hydroxyphenyl Retinamide Inhibits Flavivirus Replication

2014 ◽  
Vol 59 (1) ◽  
pp. 85-95 ◽  
Author(s):  
Margot Carocci ◽  
Stephen M. Hinshaw ◽  
Mary A. Rodgers ◽  
Valerie A. Villareal ◽  
Dominique J. Burri ◽  
...  
Keyword(s):  
Cell Culture ◽  
Antiviral Activity ◽  
Mammalian Cell Culture ◽  
Antiviral Agent ◽  
Denv Infection ◽  
Effective Vaccine ◽  
Bioactive Lipids ◽  
Content Type ◽  
Long Chain

ABSTRACTDengue virus (DENV), a member of theFlaviviridaefamily, is a mosquito-borne pathogen and the cause of dengue fever. The increasing prevalence of DENV worldwide heightens the need for an effective vaccine and specific antivirals. Due to the dependence of DENV upon the lipid biosynthetic machinery of the host cell, lipid signaling and metabolism present unique opportunities for inhibiting viral replication. We screened a library of bioactive lipids and modulators of lipid metabolism and identified 4-hydroxyphenyl retinamide (4-HPR) (fenretinide) as an inhibitor of DENV in cell culture. 4-HPR inhibits the steady-state accumulation of viral genomic RNA and reduces viremia when orally administered in a murine model of DENV infection. The molecular target responsible for this antiviral activity is distinct from other known inhibitors of DENV but appears to affect other members of theFlaviviridae, including the West Nile, Modoc, and hepatitis C viruses. Although long-chain ceramides have been implicated in DENV replication, we demonstrate that DENV is insensitive to the perturbation of long-chain ceramides in mammalian cell culture and that the effect of 4-HPR on dihydroceramide homeostasis is separable from its antiviral activity. Likewise, the induction of reactive oxygen species by 4-HPR is not required for the inhibition of DENV. The inhibition of DENVin vivoby 4-HPR, combined with its well-established safety and tolerability in humans, suggests that it may be repurposed as a pan-Flaviviridaeantiviral agent. This work also illustrates the utility of bioactive lipid screens for identifying critical interactions of DENV and other viral pathogens with host lipid biosynthesis, metabolism, and signal transduction.

scholarly journals Antiviral Efficacy of Ribavirin and Favipiravir against Hantaan Virus

2021 ◽  
Vol 9 (6) ◽  
pp. 1306
Author(s):  
Jennifer Mayor ◽  
Olivier Engler ◽  
Sylvia Rothenberger
Keyword(s):  
High Risk ◽  
Antiviral Activity ◽  
Low Dose ◽  
Rna Viruses ◽  
Virus Transmission ◽  
Antiviral Agent ◽  
Hemorrhagic Fever ◽  
Hantaan Virus ◽  
Population Movements ◽  
Ecological Changes

Ecological changes, population movements and increasing urbanization promote the expansion of hantaviruses, placing humans at high risk of virus transmission and consequent diseases. The currently limited therapeutic options make the development of antiviral strategies an urgent need. Ribavirin is the only antiviral used currently to treat hemorrhagic fever with renal syndrome (HFRS) caused by Hantaan virus (HTNV), even though severe side effects are associated with this drug. We therefore investigated the antiviral activity of favipiravir, a new antiviral agent against RNA viruses. Both ribavirin and favipiravir demonstrated similar potent antiviral activity on HTNV infection. When combined, the efficacy of ribavirin is enhanced through the addition of low dose favipiravir, highlighting the possibility to provide better treatment than is currently available.

scholarly journals Immune Serum Produced by DNA Vaccination Protects Hamsters against Lethal Respiratory Challenge with Andes Virus

2007 ◽  
Vol 82 (3) ◽  
pp. 1332-1338 ◽  
Author(s):  
Jay W. Hooper ◽  
Anthony M. Ferro ◽  
Victoria Wahl-Jensen
Keyword(s):  
Dna Vaccine ◽  
Neutralizing Antibodies ◽  
Lethal Dose ◽  
Case Fatality ◽  
Immune Serum ◽  
Human Infection ◽  
M Gene ◽  
Hamster Model ◽  
Highly Pathogenic ◽  
Andes Virus

ABSTRACT Hantavirus pulmonary syndrome (HPS) is a highly pathogenic disease (40% case fatality rate) carried by rodents chronically infected with certain viruses within the genus Hantavirus of the family Bunyaviridae. The primary mode of transmission to humans is thought to be inhalation of excreta from infected rodents; however, ingestion of contaminated material and rodent bites are also possible modes of transmission. Person-to-person transmission of HPS caused by one species of hantavirus, Andes virus (ANDV), has been reported. Previously, we reported that ANDV injected intramuscularly causes a disease in Syrian hamsters that closely resembles HPS in humans. Here we tested whether ANDV was lethal in hamsters when it was administered by routes that more accurately model the most common routes of human infection, i.e., the subcutaneous, intranasal, and intragastric routes. We discovered that ANDV was lethal by all three routes. Remarkably, even at very low doses, ANDV was highly pathogenic when it was introduced by the mucosal routes (50% lethal dose [LD50], ∼100 PFU). We performed passive transfer experiments to test the capacity of neutralizing antibodies to protect against lethal intranasal challenge. The neutralizing antibodies used in these experiments were produced in rabbits vaccinated by electroporation with a previously described ANDV M gene-based DNA vaccine, pWRG/AND-M. Hamsters that were administered immune serum on days −1 and +5 relative to challenge were protected against intranasal challenge (21 LD50). These findings demonstrate the utility of using the ANDV hamster model to study transmission across mucosal barriers and provide evidence that neutralizing antibodies produced by DNA vaccine technology can be used to protect against challenge by the respiratory route.

scholarly journals Combination Regimens of Favipiravir Plus Interferon Alpha Inhibit Chikungunya Virus Replication in Clinically Relevant Human Cell Lines

2021 ◽  
Vol 9 (2) ◽  
pp. 307
Author(s):  
Evelyn J. Franco ◽  
Xun Tao ◽  
Kaley C. Hanrahan ◽  
Jieqiang Zhou ◽  
Jürgen B. Bulitta ◽  
...  
Keyword(s):  
Combination Therapy ◽  
Antiviral Activity ◽  
Viral Replication ◽  
Cell Lines ◽  
Interferon Alpha ◽  
Chikungunya Virus ◽  
Plaque Assay ◽  
Human Infection ◽  
Viral Burden ◽  
Combination Regimens

Chikungunya virus (CHIKV) is an alphavirus associated with a broad tissue tropism for which no antivirals or vaccines are approved. This study evaluated the antiviral potential of favipiravir (FAV), interferon-alpha (IFN), and ribavirin (RBV) against CHIKV as mono- and combination-therapy in cell lines that are clinically relevant to human infection. Cells derived from human connective tissue (HT-1080), neurons (SK-N-MC), and skin (HFF-1) were infected with CHIKV and treated with different concentrations of FAV, IFN, or RBV. Viral supernatant was sampled daily and the burden was quantified by plaque assay on Vero cells. FAV and IFN were the most effective against CHIKV on various cell lines, suppressing the viral burden at clinically achievable concentrations; although the degree of antiviral activity was heavily influenced by cell type. RBV was not effective and demonstrated substantial toxicity, indicating that it is not a feasible candidate for CHIKV. The combination of FAV and IFN was then assessed on all cell lines. Combination therapy enhanced antiviral activity in HT-1080 and SK-N-MC cells, but not in HFF-1 cells. We developed a pharmacokinetic/pharmacodynamic model that described the viral burden and inhibitory antiviral effect. Simulations from this model predicted clinically relevant concentrations of FAV plus IFN completely suppressed CHIKV replication in HT-1080 cells, and considerably slowed down the rate of viral replication in SK-N-MC cells. The model predicted substantial inhibition of viral replication by clinical IFN regimens in HFF-1 cells. Our results highlight the antiviral potential of FAV and IFN combination regimens against CHIKV in clinically relevant cell types.

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