Post-exposure treatments for Ebola and Marburg virus infections

Abstract

| The filoviruses -Ebola virus and Marburg virus -cause lethal haemorrhagic fever in humans and non-human primates (NHPs). Filoviruses present a global health threat both as naturally acquired diseases and as potential agents of bioterrorism. In the recent 2013-2016 outbreak of Ebola virus, the most promising therapies for post-exposure use with demonstrated efficacy in the gold-standard NHP models of filovirus disease were unable to show statistically significant protection in patients infected with Ebola virus. This Review briefly discusses these failures and what has been learned from these experiences, and summarizes the current status of post-exposure medical countermeasures in development, including antibodies, small interfering RNA and small molecules. We outline how our current knowledge could be applied to the identification of novel interventions and ways to use interventions more effectively. R E V I E W SNATURE REVIEWS | DRUG DISCOVERY VOLUME 17 | JUNE 2018 | 413 © 2 0 1 8 M a c m i l l a n P u b l i s h e r s L i m i t e d , p a r t o f S p r i n g e r N a t u r e . A l l r i g h t s r e s e r v e d . AstheniaMuscular weakness. MyalgiaMuscular pain. ArthralgiaJoint pain. LeukopeniaA condition of having a low number of circulating leukocytes, including neutrophils, eosinophils, basophils, lymphocytes and monocytes. LymphocytopeniaA condition of having a low number of circulating leukocytes, including natural killer cells, T cells and B cells. ThrombocytopeniaA condition of having a low number of circulating thrombocytes, also known as platelets.and Ebolavirus. The Marburgvirus genus contains a single species, Marburg marburgvirus, which contains two members, Marburg virus (MARV) and Ravn virus (RAVV). The Ebolavirus genus consists of five distinct species: Bundibugyo ebolavirus (BDBV), Reston ebolavirus (RESTV), Sudan ebolavirus (SUDV), Tai Forest ebolavirus (TAFV; previously termed 'Côte d'Ivoire ebolavirus' but more commonly known as 'Ivory Coast ebolavirus') and Zaire ebolavirus (EBOV). MARV, RAVV, BDBV, SUDV and EBOV are important human pathogens, with case fatality rates often up to 90% for MARV, RAVV and EBOV, and around 55% for SUDV 8,10 . On the basis of two small outbreaks in 2007 and 2012, BDBV seems to be the least pathogenic, with a case fatality rate of about 40-48% 11,12 . In 1994, TAFV was associated with a number of deaths in chimpanzees and a single symptomatic but non-lethal human infection in the Republic of Côte d'Ivoire 13,14 . RESTV is lethal for macaques but is not thought to cause disease in humans 15 . An outbreak of RESTV was reported in pigs in the Philippines in 2008; however, it remains uncertain whether the disease observed in the pigs was caused by RESTV or other agents reported to have co-infected the animals 16 . Clinical manifestationsClinical and laboratory signs of disease caused by filovirus infection are nonspecific and usually associated with an incubation period of 2-21 days (mean 4-10 days) 8,17 . Illness begins with an abrupt onset of fever, astheni...

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