Neglected filoviruses

Abstract

Eight viruses are currently assigned to the family Filoviridae Marburg virus, Sudan virus and, in particular, Ebola virus have received the most attention both by researchers and the public from 1967 to 2013. During this period, natural human filovirus disease outbreaks occurred sporadically in Equatorial Africa and, despite high case-fatality rates, never included more than several dozen to a few hundred infections per outbreak. Research emphasis shifted almost exclusively to Ebola virus in 2014, when this virus was identified as the cause of an outbreak that has thus far involved more than 28 646 people and caused more than 11 323 deaths in Western Africa. Consequently, major efforts are currently underway to develop licensed medical countermeasures against Ebola virus infection. However, the ecology of and mechanisms behind Ebola virus emergence are as little understood as they are for all other filoviruses. Consequently, the possibility of the future occurrence of a large disease outbreak caused by other less characterized filoviruses (i.e. Bundibugyo virus, Lloviu virus, Ravn virus, Reston virus and Taï Forest virus) is impossible to rule out. Yet, for many of these viruses, not even rudimentary research tools are available, let alone medical countermeasures. This review summarizes the current knowledge on these less well-characterized filoviruses.

Keywords: Ebola; Filoviridae; cuevavirus; ebolavirus; filovirus; marburgvirus.

Graphical Abstract Figure.

While Ebola virus dominates the headlines, other filoviruses remain largely uncharacterized but may pose equal risks to humans.

Figure 1.

Geographical location of primary index cases causing disease outbreaks due to neglected filovirus infections. Countries with index cases are shown in light brown with outbreak locations marked as bold dots (disease outbreaks due to more prominent filoviruses, EBOV, SUDV or MARV, are indicated via faded dots for reference). Former country names are listed in parenthesis under present names. COD: Democratic Republic of the Congo; COG: Republic of the Congo. Adopted from (Kuhn 2015).

Figure 2.

Organization of neglected filovirus genomes. Genes and open reading frames (ORFs) are shown as rectangles and horizontal arrows, respectively. Wavy lines indicate incomplete sequencing of 3′ leader or 5′ trailer sequences. Entries for prominent filoviruses, EBOV, SUDV or MARV, are muted.