Interferon-γ Inhibits Ebola Virus Infection

Rhein, Bethany A.; Powers, Linda S.; Rogers, Kai J.; Anantpadma, Manu; Singh, Brajesh K.; Sakurai, Yoshio; Bair, Thomas B.; Miller-Hunt, Catherine L.; Sinn, Patrick L.; Davey, Robert A.; Monick, Martha M.; Maury, Wendy

doi:10.1371/journal.ppat.1005263

Cited by 81 publications

(113 citation statements)

References 96 publications

(116 reference statements)

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“…Tilorone gave a 50% effective concentration (EC 50 ) of 230 nM (35), making it one of the most potent small-molecule inhibitors of EBOV reported. This result is also consistent with reports showing IFN-inhibits EBOV infection (37).…”

supporting

confidence: 93%

Efficacy of Tilorone Dihydrochloride against Ebola Virus Infection

Ekins

Lingerfelt

Comer

et al. 2018

Antimicrob Agents Chemother

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Tilorone dihydrochloride (tilorone) is a small-molecule, orally bioavailable drug that is used clinically as an antiviral outside the United States. A machinelearning model trained on anti-Ebola virus (EBOV) screening data previously identified tilorone as a potent in vitro EBOV inhibitor, making it a candidate for the treatment of Ebola virus disease (EVD). In the present study, a series of in vitro ADMET (absorption, distribution, metabolism, excretion, toxicity) assays demonstrated the drug has excellent solubility, high Caco-2 permeability, was not a P-glycoprotein substrate, and had no inhibitory activity against five human CYP450 enzymes (3A4, 2D6, 2C19, 2C9, and 1A2). Tilorone was shown to have 52% human plasma protein binding with excellent plasma stability and a mouse liver microsome half-life of 48 min. Dose range-finding studies in mice demonstrated a maximum tolerated single dose of 100 mg/kg of body weight. A pharmacokinetics study in mice at 2-and 10-mg/kg dose levels showed that the drug is rapidly absorbed, has dosedependent increases in maximum concentration of unbound drug in plasma and areas under the concentration-time curve, and has a half-life of approximately 18 h in both males and females, although the exposure was ϳ2.5-fold higher in male mice. Tilorone doses of 25 and 50 mg/kg proved efficacious in protecting 90% of mice from a lethal challenge with mouse-adapted with once-daily intraperitoneal (i.p.) dosing for 8 days. A subsequent study showed that 30 mg/kg/day of tilorone given i.p. starting 2 or 24 h postchallenge and continuing through day 7 postinfection was fully protective, indicating promising activity for the treatment of EVD.

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supporting

confidence: 93%

Efficacy of Tilorone Dihydrochloride against Ebola Virus Infection

Ekins

Lingerfelt

Comer

et al. 2018

Antimicrob Agents Chemother

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“…8C and D). However, in the case of Ebola virus, postchallenge treatment was more efficacious (53), and other studies have shown that multiple treatments with IFN-␥ protected mice from a lethal challenge with vaccinia virus via the respiratory route (71). EHV-1 infection did not cause a decrease in the viability of IFN-␥-treated MH-S alveolar macrophages (data not shown).…”

Section: Discussionmentioning

confidence: 81%

“…Severe murine lung immunopathology elicited by RacL11 correlated with early production of macrophage inflammatory proteins 1␣, 1␤, and 2 and tumor necrosis factor alpha (23). In a cell culture model of Ebola virus infection of mouse macrophages, murine IFN-␥ provided Ͼ95% protection with a dose of only 2 ng/ml (53). EHV-1 KyA and RacL11 were able to replicate in MH-S murine alveolar macrophages, and the EHV-1 regulatory proteins IEP (immediate early protein) and EICP0 were expressed at 6 hpi ( Fig.…”

Section: Resultsmentioning

confidence: 97%

Immunization with Attenuated Equine Herpesvirus 1 Strain KyA Induces Innate Immune Responses That Protect Mice from Lethal Challenge

Kim

Shakya

O’Callaghan

2016

J Virol

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Equine herpesvirus 1 (EHV-1) is a major pathogen affecting equines worldwide. The virus causes respiratory disease, abortion, and, in some cases, neurological disease. EHV-1 strain KyA is attenuated in the mouse and equine, whereas wild-type strain RacL11 induces severe inflammation of the lung, causing infected mice to succumb at 4 to 6 days postinfection. Our previous results showed that KyA Equine herpesvirus 1 (EHV-1), a member of the family Herpesviridae and the subfamily Alphaherpesvirinae, is the causative agent of a number of equine pathological states, including severe disease of the central nervous system, respiratory infections, and abortion storms (1-4). Respiratory transmission of this highly contagious virus has resulted in disastrous outbreaks of disease in domestic horse populations and has had significant economic impact on the equine industry. EHV-1 infection of the horse generates a short-lived humoral response but does not confer long-term protection, since disease often occurs following natural infection (5, 6).A model that closely mimics EHV-1 infection in the natural host has been established with various strains of mice (7). Common features include replication in the respiratory mucosae, the development of pneumonitis, cell-associated viremia, and abortion (7,8). Various EHV-1 glycoproteins, including gB, gC, gD, and gH, were capable of inducing neutralizing antibodies (9-14). EHV-1-specific CD8 ϩ class I major histocompatibility complex (MHC)-restricted cytotoxic T lymphocytes (CTL) were identified in the peripheral blood mononuclear cells of infected horses, reaching maximal levels 2 to 3 weeks postinfection (15,16). Intranasal inoculation of mice with an attenuated EHV-1 strain, KyA, resulted in the production of a primary virus-specific CTL response in the draining mediastinal lymph nodes (17). In this model, EHV-1-specific CTL activity was mediated by class I MHC-restricted CD8 ϩ T cells (17). The nonpathogenic EHV-1 strain Kentucky A (KyA) is attenuated in mice and horses, whereas the wild-type pathogenic strain RacL11 induces severe inflammatory cell infiltration in the lung, such that infected mice succumb at 4 to 6 days postinfection (dpi) (Fig. 1) (18-23). RacL11 was isolated from an aborted fetus (24). KyA has a long history of passage outside the natural host and

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“…IFN-␤, used for treatment at an early time postexposure, was effective in prolonging the survival time of rhesus macaques but did not improve the survival rate (23). Another study revealed that IFN-␥ had significant anti-EBOV effects in vivo (24). One recent in vitro study found that type I IFNs showed efficacy in pretreatments performed 24 h before viral infection at a low multiplicity of infection (MOI), while IFN-␥ showed even lower efficacy.…”

Section: Discussionmentioning

confidence: 99%

Novel Stable Ebola Virus Minigenome Replicon Reveals Remarkable Stability of the Viral Genome

Tao

Gan

Guo

et al. 2017

J Virol

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Ebola virus (EBOV) causes severe hemorrhagic fever in humans and other primates with a high case fatality rate. No approved drug or vaccine of EBOV is available, which necessitates better understanding of the virus life cycle. Studies on EBOV have been hampered because experimentations involving live virus are restricted to biosafety level 4 (BSL4) laboratories. The EBOV minigenome system has provided researchers with the opportunity to study EBOV under BSL2 conditions. Here, we developed a novel EBOV minigenome replicon which, to our knowledge, is the first EBOV cell culture system that can stably replicate and transcribe the EBOV minigenome. The minigenomic RNA harboring a Gaussia luciferase and hygromycinresistant marker can replicate for months in a helper cell stably expressing viral nucleoprotein (NP), viral protein 35 (VP35), VP30, and L proteins. Quantification of viral RNA (vRNA), cRNA, and mRNA levels of the EBOV minigenome demonstrated that the stable EBOV replicon had much-more-active minigenome replication than previously developed transient-transfection-based EBOV minigenome systems, which recapitulate viral primary transcription more than genome replication. Interestingly, minigenome replication in the stable EBOV replicon cells was insensitive to interferon treatment or RNA interference. Moreover, RNase digestion of the replicon cell lysates revealed the remarkably stable nature of the EBOV minigenomic vRNA ribonucleoprotein complex, which may help improve understanding of EBOV persistence in convalescent patients. IMPORTANCEThe scope and severity of the recent Ebola outbreak in Western Africa justified a more comprehensive investigation of the causative risk group 4 agent Ebola virus (EBOV). Study of EBOV replication and antiviral development can be facilitated by developing a cell culture system that allows experimentation under biosafety level 2 conditions. Here, we developed a novel stable EBOV minigenome replicon which, to our knowledge, is the first EBOV cell culture system that can stably replicate and transcribe the EBOV minigenome. The replicon system had more-active genome replication than previously developed transient-transfection-based EBOV minigenome systems, providing a convenient surrogate system to study EBOV replication. Furthermore, self-replicating minigenomic vRNA in the replicon cells displayed strong stability in response to interferon treatment, RNA silencing, and RNase digestion, which may provide an explanation for the persistence of EBOV in survivors.

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Interferon-γ Inhibits Ebola Virus Infection

Cited by 81 publications

References 96 publications

Efficacy of Tilorone Dihydrochloride against Ebola Virus Infection

Efficacy of Tilorone Dihydrochloride against Ebola Virus Infection

Immunization with Attenuated Equine Herpesvirus 1 Strain KyA Induces Innate Immune Responses That Protect Mice from Lethal Challenge

Novel Stable Ebola Virus Minigenome Replicon Reveals Remarkable Stability of the Viral Genome

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