Asfarviridae is a family of viruses that primarily infects swine, resulting in an onset of African swine fever. There is a single genus in this family: Asfivirus. The name of this family and genus are derived from the acronym: African swine fever and related viruses. Only a single species has been described to date for this genus.
This group of viruses are the only known arthropod borne DNA viruses. The viruses in this family are all enveloped and have double-stranded DNA genomes.
The Asfarvirus exhibits some similarities in genome structure and replication strategies to the poxviruses and phycodnaviruses but has different virion structure from poxviruses and several other properties that distinguish it from the latter.
The virons consist of an envelope, a capsid, a core and a nucleoprotein complex. They are spherical and measure 175-215 nanometers (nm) in diameter. The capsid is icosahedral (T=189-217) with a diameter of 172-191 nm and appear hexagonal in outline. The capsomers measure 13 nm in diameter and there are 1892-2172 of these per capsid.
The genome is linear double stranded DNA and between 170 and 190 kilobases in length. Its guanine + cytosine content is 39 %.
The virus can be grown in cell culture but cytopathic effects may be absent. Acidophilic, intracytoplasmic inclusion bodies may be visible in biopsies or post mortum material. Replication is cytoplasmic and the virons mature by budding from plasma membrane.
The viruses in this family infect domestic pigs and their relatives. The natural hosts are warthogs (Phacochoerus africanus), bush pigs (Potamochoerus porcus) and argasid ticks (Ornithodoros species). Young warthogs when infected develop a high viraemia and are infectious to ticks. Older warthogs are generally immune to infection. The virus can replicate within the ticks. Transtadial, transovarial and sexual spread within the ticks occurs.