Bombali ebolavirus is the sixth known member of the genus Ebolavirus. It was identified in 2016–2018 in the tissues and oral swabs of free‑tailed bats (Mops condylurus and Chaerephon pumilus) in Sierra Leone and later detected in similar bat species in Kenya, Guinea and Liberia. The virus belongs to the family Filoviridae and has a negative‑sense, single‑stranded RNA genome of about 19 kilobases. To date there have been no documented human cases of Bombali ebolavirus infection, but the discovery underscores the diversity of ebolaviruses circulating in bat reservoirs.
Classification, Reservoir and Properties
Bombali ebolavirus shares the general structure of other ebolaviruses. Its genome encodes seven structural proteins—nucleoprotein (NP), VP35, VP40, glycoprotein (GP), VP30, VP24 and the RNA‑dependent RNA polymerase (L)—organized in a linear, non‑segmented arrangement. Virions are filamentous and enveloped. Phylogenetic analyses place Bombali ebolavirus as a distinct lineage within the genus Ebolavirus, separate from Zaire, Sudan, Bundibugyo, Taï Forest and Reston ebolaviruses. The virus was first detected during the PREDICT surveillance program in Sierra Leone when researchers sampled bats inhabiting residential buildings. Viral RNA and infectious virus were recovered from Mops condylurus and Chaerephon pumilus bats, species that roost in close proximity to humans. Subsequent surveillance identified Bombali ebolavirus in bats in eastern and western Africa, suggesting a wide geographic distribution. Laboratory experiments indicate that the virus can infect human and bat cell lines, raising questions about zoonotic potential. However, there is currently no evidence that Bombali ebolavirus causes disease in humans or animals. As with other ebolaviruses, fruit bats or insectivorous bats are considered reservoirs, and the virus likely circulates asymptomatically among them.
Surveillance and Public Health Relevance
The discovery of Bombali ebolavirus highlights the importance of wildlife surveillance programs aimed at identifying emerging pathogens. Sampling of bats in Sierra Leone in 2016–2018 led to the isolation of viral genomes that expanded the known diversity of ebolaviruses. Detection in domestic settings underscores that bats cohabit with humans, creating opportunities for spillover. The virus has since been found in bats in Kenya, Guinea and Liberia, demonstrating a broad African range. Laboratory studies show that Bombali ebolavirus glycoprotein mediates entry into human cells via the Niemann‑Pick C1 receptor, the same pathway used by other ebolaviruses, but replication competence and pathogenicity in humans are unknown. Public health agencies have not reported human cases, and no outbreaks have been linked to Bombali ebolavirus. Ongoing surveillance and risk communication with communities living near bat roosts are crucial to reduce potential exposure. The finding of Bombali ebolavirus also informs vaccine and therapeutic development by illustrating antigenic diversity within the genus.
Bombali ebolavirus currently represents an evolutionary branch of the Ebolavirus genus known only from bat hosts. Continued monitoring of bat populations and research into viral biology will determine whether it poses any risk to human health.
Related Terms: Zaire Ebolavirus, Sudan Ebolavirus, Bundibugyo Ebolavirus, Taï Forest Ebolavirus, Reston Ebolavirus