Therapeutic efficacy of the small molecule GS-5734 against Ebola virus in rhesus monkeys.

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Abstract

The most recent Ebola virus outbreak in West Africa, which was unprecedented in the number of cases and fatalities, geographic distribution, and number of nations affected, highlights the need for safe, effective, and readily available antiviral agents for treatment and prevention of acute Ebola virus (EBOV) disease (EVD) or sequelae. No antiviral therapeutics have yet received regulatory approval or demonstrated clinical efficacy. Here we report the discovery of a novel small molecule GS-5734, a monophosphoramidate prodrug of an adenosine analogue, with antiviral activity against EBOV. GS-5734 exhibits antiviral activity against multiple variants of EBOV and other filoviruses in cell-based assays. The pharmacologically active nucleoside triphosphate (NTP) is efficiently formed in multiple human cell types incubated with GS-5734 in vitro, and the NTP acts as an alternative substrate and RNA-chain terminator in primer-extension assays using a surrogate respiratory syncytial virus RNA polymerase. Intravenous administration of GS-5734 to nonhuman primates resulted in persistent NTP levels in peripheral blood mononuclear cells (half-life, 14 h) and distribution to sanctuary sites for viral replication including testes, eyes, and brain. In a rhesus monkey model of EVD, once-daily intravenous administration of 10 mg kg(-1) GS-5734 for 12 days resulted in profound suppression of EBOV replication and protected 100% of EBOV-infected animals against lethal disease, ameliorating clinical disease signs and pathophysiological markers, even when treatments were initiated three days after virus exposure when systemic viral RNA was detected in two out of six treated animals. These results show the first substantive post-exposure protection by a small-molecule antiviral compound against EBOV in nonhuman primates. The broad-spectrum antiviral activity of GS-5734 in vitro against other pathogenic RNA viruses, including filoviruses, arenaviruses, and coronaviruses, suggests the potential for wider medical use. GS-5734 is amenable to large-scale manufacturing, and clinical studies investigating the drug safety and pharmacokinetics are ongoing.

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Successful treatment of advanced Ebola virus infection with T-705 (favipiravir) in a small animal model.

Lisa Oestereich, Anja Lüdtke, Stephanie Wurr … (2014)

Outbreaks of Ebola hemorrhagic fever in sub-Saharan Africa are associated with case fatality rates of up to 90%. Currently, neither a vaccine nor an effective antiviral treatment is available for use in humans. Here, we evaluated the efficacy of the pyrazinecarboxamide derivative T-705 (favipiravir) against Zaire Ebola virus (EBOV) in vitro and in vivo. T-705 suppressed replication of Zaire EBOV in cell culture by 4log units with an IC90 of 110μM. Mice lacking the type I interferon receptor (IFNAR(-)(/)(-)) were used as in vivo model for Zaire EBOV-induced disease. Initiation of T-705 administration at day 6 post infection induced rapid virus clearance, reduced biochemical parameters of disease severity, and prevented a lethal outcome in 100% of the animals. The findings suggest that T-705 is a candidate for treatment of Ebola hemorrhagic fever. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

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Ebola RNA Persistence in Semen of Ebola Virus Disease Survivors - Preliminary Report.

Gibrilla Deen, Nathalie Broutet, Wenbo Xu … (2017)

Background Ebola virus has been detected in the semen of men after their recovery from Ebola virus disease (EVD), but little information is available about its prevalence or the duration of its persistence. We report the initial findings of a pilot study involving survivors of EVD in Sierra Leone. Methods We enrolled a convenience sample of 100 male survivors of EVD in Sierra Leone, at different times after their recovery from EVD, and recorded self-reported information about sociodemographic characteristics, the EVD episode, and health status. Semen specimens obtained at baseline were tested by means of a quantitative reverse-transcriptase-polymerase-chain-reaction (RT-PCR) assay with the use of the target-gene sequences of NP and VP40. Results A total of 93 participants provided an initial semen specimen for analysis, of whom 46 (49%) had positive results on quantitative RT-PCR. Ebola virus RNA was detected in the semen of all 9 men who had a specimen obtained 2 to 3 months after the onset of EVD, in the semen of 26 of 40 (65%) who had a specimen obtained 4 to 6 months after onset, and in the semen of 11 of 43 (26%) who had a specimen obtained 7 to 9 months after onset; the results for 1 participant who had a specimen obtained at 10 months were indeterminate. The median cycle-threshold values (for which higher values indicate lower RNA levels) were 32.0 with the NP gene target and 31.1 with the VP40 gene target for specimens obtained at 2 to 3 months, 34.5 and 32.3, respectively, for specimens obtained at 4 to 6 months, and 37.0 and 35.6, respectively, for specimens obtained at 7 to 9 months. Conclusions These data showed the persistence of Ebola virus RNA in semen and declining persistence with increasing months since the onset of EVD. We do not yet have data on the extent to which positivity on RT-PCR is associated with virus infectivity. Although cases of suspected sexual transmission of Ebola have been reported, they are rare; hence the risk of sexual transmission of the Ebola virus is being investigated. (Funded by the World Health Organization and others.).

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Delayed treatment of Ebola virus infection with plant-derived monoclonal antibodies provides protection in rhesus macaques.

G. Olinger, J. Pettitt, D. Kim … (2012)

Filovirus infections can cause a severe and often fatal disease in humans and nonhuman primates, including great apes. Here, three anti-Ebola virus mouse/human chimeric mAbs (c13C6, h-13F6, and c6D8) were produced in Chinese hamster ovary and in whole plant (Nicotiana benthamiana) cells. In pilot experiments testing a mixture of the three mAbs (MB-003), we found that MB-003 produced in both manufacturing systems protected rhesus macaques from lethal challenge when administered 1 h postinfection. In a pivotal follow-up experiment, we found significant protection (P < 0.05) when MB-003 treatment began 24 or 48 h postinfection (four of six survived vs. zero of two controls). In all experiments, surviving animals that received MB-003 experienced little to no viremia and had few, if any, of the clinical symptoms observed in the controls. The results represent successful postexposure in vivo efficacy by a mAb mixture and suggest that this immunoprotectant should be further pursued as a postexposure and potential therapeutic for Ebola virus exposure.