siRNA rescues nonhuman primates from advanced Marburg and Ravn virus disease
Emily P. Thi, … , Ian MacLachlan, Thomas W. Geisbert
Emily P. Thi, … , Ian MacLachlan, Thomas W. Geisbert
Published December 1, 2017; First published November 6, 2017
Citation Information: J Clin Invest. 2017;127(12):4437-4448. https://doi.org/10.1172/JCI96185.
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Research Article Infectious disease Virology

siRNA rescues nonhuman primates from advanced Marburg and Ravn virus disease

Abstract

Ebolaviruses and marburgviruses belong to the family Filoviridae and cause high lethality in infected patients. There are currently no licensed filovirus vaccines or antiviral therapies. The development of broad-spectrum therapies against members of the Marburgvirus genus, including Marburg virus (MARV) and Ravn virus (RAVV), is difficult because of substantial sequence variability. RNAi therapeutics offer a potential solution, as identification of conserved target nucleotide sequences may confer activity across marburgvirus variants. Here, we assessed the therapeutic efficacy of lipid nanoparticle (LNP) delivery of a single nucleoprotein–targeting (NP-targeting) siRNA in nonhuman primates at advanced stages of MARV or RAVV disease to mimic cases in which patients begin treatment for fulminant disease. Sixteen rhesus monkeys were lethally infected with MARV or RAVV and treated with NP siRNA-LNP, with MARV-infected animals beginning treatment four or five days after infection and RAVV-infected animals starting treatment three or six days after infection. While all untreated animals succumbed to disease, NP siRNA-LNP treatment conferred 100% survival of RAVV-infected macaques, even when treatment began just 1 day prior to the death of the control animals. In MARV-infected animals, day-4 treatment initiation resulted in 100% survival, and day-5 treatment resulted in 50% survival. These results identify a single siRNA therapeutic that provides broad-spectrum protection against both MARV and RAVV.

Authors

Emily P. Thi, Chad E. Mire, Amy C.H. Lee, Joan B. Geisbert, Raul Ursic-Bedoya, Krystle N. Agans, Marjorie Robbins, Daniel J. Deer, Robert W. Cross, Andrew S. Kondratowicz, Karla A. Fenton, Ian MacLachlan, Thomas W. Geisbert

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Figure 1

NP-718m mediates effective silencing of both MARV and RAVV and confers survival benefit to lethally infected NHPs.

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NP-718m mediates effective silencing of both MARV and RAVV and confers s...
(A) Despite a single nucleotide mismatch present in NP-718m against RAVV target sequences, NP-718m showed activity similar to that of NP-718m RAVV in a dual-luciferase reporter assay assessment of siRNA activity (NP-718m RAVV had perfect complementarity to RAVV sequences after mismatch correction). The target sequence for NP-143m was conserved against both MARV and RAVV. Six doses of each siRNA at 0.0032 nM, 0.016 nM, 0.008 nM, 0.4 nM, 2 nM, and 10 nM, respectively, were assessed in HepG2 cells transfected with a luciferase reporter plasmid encoding MARV or RAVV NP mRNA sequences. Cell lysates were quantitated for Renilla luciferase (fused to MARV or RAVV target transgene expression) and firefly luciferase signals. The Renilla luciferase signal was normalized to the firefly luciferase signal and expressed as the percentage of gene expression relative to a plasmid-only control (pDNA) assigned a value of 100%. Data represent the mean of technical triplicates ± SD of 1 experiment. NP-718m–LNP treatment conferred survival benefit to rhesus macaques lethally infected with (B) MARV or (C) RAVV. *P = 0.0357, by 1-tailed Fisher’s exact test.