African swine fever virus | |
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Electron micrograph of a virus particle | |
Virus classification | |
Group: | Group I (dsDNA) |
Family: | Asfarviridae |
Genus: | Asfivirus |
Species: | African swine fever virus |
African swine fever virus (ASFV) is the causative agent of African swine fever (ASF). The virus causes a haemorrhagic fever with high mortality rates in pigs, but persistently infects its natural hosts, warthogs, bushpigs, and soft ticks of the Ornithodoros genus, with no disease signs.
ASFV is a large, double-stranded DNA virus which replicates in the cytoplasm of infected cells, and is the only member of the Asfarviridae family. ASFV infects domestic pigs, warthogs and bushpigs, as well as soft ticks (Ornithodoros), which likely act as a vector.
ASFV is the only known virus with a double-stranded DNA genome transmitted by arthropods. The virus causes a lethal haemorraghic disease in domestic pigs. Some isolates can cause death of animals within as quickly as a week after infection. In all other species, the virus causes no obvious disease. ASFV is endemic to sub-Saharan Africa and exists in the wild through a cycle of infection between ticks and wild pigs, bushpigs, and warthogs. The disease was first described after European settlers brought pigs into areas endemic with ASFV and, as such, is an example of an 'emerging infectious disease'.
ASFV is a large, icosahedral, double-stranded DNA virus with a linear genome containing at least 150 genes. The number of genes differs slightly between different isolates of the virus. ASFV has similarities to the other large DNA viruses, e.g., poxvirus, iridovirus, and mimivirus. In common with other viral haemorrhagic fevers, the main target cells for replication are those of monocyte, macrophage lineage. Entry of the virus into the host cell is receptor-mediated, but the precise mechanism of endocytosis is presently unclear.