ICTV Virus Taxonomy Profile: Asfarviridae

Abstract

The family Asfarviridae includes the single species African swine fever virus, isolates of which have linear dsDNA genomes of 170-194 kbp. Virions have an internal core, an internal lipid membrane, an icosahedral capsid and an outer lipid envelope. Infection of domestic pigs and wild boar results in an acute haemorrhagic fever with transmission by contact or ingestion, or by ticks of the genus Ornithodoros. Indigenous pigs act as reservoirs in Africa, where infection is endemic, and from where introductions occur periodically to Europe. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the Asfarviridae, which is available at www.ictv.global/report/asfarviridae.

Keywords: African swine fever virus; Asfarviridae; ICTV Report; Taxonomy.

Fig. 1.

Electron microscope images of virions of African swine fever virus. (a) Diagram of extracellular virions showing nucleoid, inner core shell, internal membrane, capsid and outer envelope. (b) Extracellular virions. The black arrow shows the outer envelope and the white arrow shows the virus membrane. Bar, 200 nm. (Image kindly provided by P. Hawes, Institute for Animal Health, UK).

Fig. 2.

African swine fever virus infectious cycle. Virus enters the cell by clathrin-mediated endocytosis and macropinocytosis. Virions progress through the endocytic pathway and uncoat at late endosomes, where viral decapsidation and then fusion occur. This liberates viral cores to start replication in a cytoplasmic site at the microtubule-organizing centre known as the viral factory. Newly synthesized virions are assembled in the viral factory and exit the cell by budding. Figure reproduced with permission from [8].