Filoviridae

Filoviridae is a family of enveloped, filamentous viruses that possess nonsegmented, negative-sense RNA genomes. Members cause viral hemorrhagic fevers in humans and nonhuman primates. The family currently contains three genera: Cuevavirus, Marburgvirus, and Ebolavirus, with multiple species in each genus, including Lloviu cuevavirus in Cuevavirus, Marburg marburgvirus and Ravn virus in Marburgvirus, and several species within Ebolavirus such as Zaire ebolavirus, Sudan ebolavirus, Taï Forest ebolavirus, Bundibugyo ebolavirus, and Reston ebolavirus.

Virions are enveloped and filamentous, with shapes ranging from long threads to curved filaments; they are about 80 nanometers in diameter and can reach several micrometers in length. The genome is approximately 19 kilobases in length and encodes seven structural proteins: NP, VP35, VP40, GP, VP30, VP24, and L, plus a secreted glycoprotein (sGP) produced by RNA editing. The GP mediates entry into host cells after proteolytic processing in endosomes. Replication occurs in the cytoplasm and uses the L polymerase and cofactors; VP35 and VP24 antagonize host interferon responses, contributing to pathogenicity.

Natural reservoirs are bats, particularly fruit bats, with spillover events leading to human outbreaks. Transmission between humans occurs mainly through direct contact with infected fluids or contaminated objects; aerosol spread is not considered a primary route. Outbreaks have occurred primarily in Africa, with Reston virus being notable for occasional human infections without uniform severe disease.

Vaccines and therapeutics are under development; as of the 2020s, Ervebo provides protection against Zaire ebolavirus and several monoclonal antibody therapies are approved for treatment of infection with Zaire ebolavirus. Other filoviruses lack widely licensed vaccines, and public health measures rely on isolation, contact tracing, and supportive care.