Viruses Genomes - AFRICAN SWINE FEVER VIRUS
African swine fever virus
(ASF) is one of the three most dreaded epidemic diseases of pigs
African swine fever virus has been placed in a newly created family called Asfarviridae. The name is derived from African Swine Fever And Releted Viruses. ASFV is the type species of the Asfivirus genus and is the sole member of this new family.
It was formerly classified in the family Iridoviridae.
African swine fever is an economically important haemorrhagic fever of domestic pigs caused by the ASF virus. Virus isolates vary in virulence, the most virulent cause 100% mortality but isolates of reduced virulence have emerged as the virus has circulated in domestic pigs. Pigs that recover from infection may remain persistently infected for long periods. The natural hosts for ASFV are warthogs, bushpigs and soft ticks of the Ornithodoros species ( O. moubata in Africa and O. erraticus in southern Europe). The virus persistently infects these wildlife hosts showing no signs of disease. The ability of the virus to persist in its hosts shows that it has mechanisms to evade host defence systems. The main target cells for virus replication in vivo are macrophages. ASFV is a cytoplasmic, icosahedral (having 20 plain faces), virus containing a double-stranded DNA genome of about 170 kbp. Domestic and feral pigs are the only susceptible species. Humans are not affected.
The disease is present in most of sub-Saharan Africa. It is now mainly restricted to feral pigs in small areas of Spain and Portugal. Other European countries have had incursions of the disease but, except for Sardinia, they have now all eradicated the disease.
The course of this disease takes from 1–7 days and has a variety of clinical forms. The death rate is dependent on the severity of the symptoms, with up to 100% deaths with the more severe forms. In the severe form the animal becomes depressed, has a high temperature, loss of appetite, shows incoordination, reluctance to move and often will lie down. Blue blotching of the skin of the extremities, such as ears, nose and limbs, often occurs. Nasal and eye discharges may occur. Pigs vomit and develop bloody diarrhoea and often die a few days later. . Spontaneous abortion can occur.
The virus is spread by direct contact with infected pigs. It is also spread by contaminated material from the environment
and the feeding of infected swill or meat scraps to pigs. The virus is very stable in a wide range of acid and alkaline levels
(pH 4–13) and temperatures, including those below freezing. It can survive in contaminated pig pens for at least one month
and can survive for many months in raw unprocessed frozen meat. Pigs can remain carriers of the virus for long periods, perhaps
for life. Heating to above 60°C appears to eliminate the virus.
Hierarchy Description:
- Genus: Asfivirus
- Species: African swine fever virus
Genome accession number: U18466
EMBL reference
- Taxonomy:
10497
- Medline references:
| Journal citation |
Pubmed ID |
| Virology 208(1):249-278(1995) |
11831707 |
| Virology 201(1):152-156(1994) |
8178480 |
| J. Virol. 64(5):2073-2081(1990) |
2325203 |
| J. Virol. 64(5):2064-2072(1990) |
2325202 |
| Virology 181(1):251-257(1991) |
1994575 |
| J. Virol. 68(4):2746-2751(1994) |
8139051 |
| J. Gen. Virol. 74:1633-1638(1993) |
8393914 |
| J. Gen. Virol. 74:2317-2324(1993) |
8245848 |
| Arch. Virol. 130(1-2):93-107(1993) |
8503790 |
| Virology 178(1):301-304(1990) |
2389555 |
| Nucleic Acids Res. 21(10):2423-2427(1993) |
8506138 |
| J. Virol. 67(9):5312-5320(1993) |
8102411 |
| Gene 134(2):161-174(1993) |
8262374 |
| Virology 175(2):477-484 (1990) |
2327074 |
| Gene 136(1-2):103-110(1993) |
8293992 |
| EMBO J. 12(7):2977-2987(1993) |
8335009 |
| J. Virol. 67(5):2475-2485(1993) |
8474154 |
| J. Virol. 66(6):3860-3868(1992) |
1583732 |
| Virology 193(1):531-536(1993) |
8438592 |
| Virology 193(1):319-328(1993) |
8382399 |
| Virology 206(2):1140-1144(1995) |
7856088 |
| Virology 188(2):938-947(1992) |
1316688 |
| Virus Res. 30(1):63-72(1993) |
8266720 |
| J. Virol. 68(11):7244-7252(1994) |
7933107 |
| Virology 186(1):40-52(1992) |
1309282 |
| Nucleic Acids Res. 14(17):6835-6844(1986) |
3763393 |
References:
http://www.iah.bbsrc.ac.uk/virus/Asfarviridae/
http://epix.hazard.net/topics/animal/asf.htm
http://www.iah.bbsrc.ac.uk/primary_index/current_research/groups/dixon.htm
http://www.pighealth.com/ASF.htm
http://www.fao.org/documents/show_cdr.asp?url_file=/DOCREP/003/X8491E/X8491e04.htm
http://www.aphis.usda.gov/vs/ncie/swine_manual/
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