African swine fever virus

Pictures

Picture	Title	Caption	Copyright
Title Electron micrograph Caption A micrograph of an ASF virus particle. Copyright ©J.M. Sanchez-Vizcaino (CISA)	Electron micrograph	A micrograph of an ASF virus particle.	©J.M. Sanchez-Vizcaino (CISA)
Title Histology Caption Swine macrophages infected with ASF virus showing hemadsorption. Copyright ©J.M. Sanchez-Vizcaino (CISA)	Histology	Swine macrophages infected with ASF virus showing hemadsorption.	©J.M. Sanchez-Vizcaino (CISA)

Identity

Preferred Scientific Name

• African swine fever virus (Murphy et al., 1995)

English acronym

• ASFV

Taxonomic Tree

• Domain: Virus
•     Unknown: "ssDNA viruses"
•         Unknown: "DNA viruses"
•             Order: Caudovirales
•                 Family: Asfarviridae
•                     Genus: Asfivirus
•                         Species: African swine fever virus

Diseases Table

Distribution Table

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Pathogen Characteristics

African swine fever (ASF) is caused by a large and complex icosahedral DNA virus that presents features which are common to both Iridovirus and Poxvirus families, and which is often classified as the only member of the unnamed floating genus "African swine fever-like virus" (Murphy et al., 1995). Virus particles have an average diameter of 200 nm (Breese and DeBoer, 1966) and are formed by several concentric coats with an external membrane which has a hexagonal outline. The DNA is double stranded; between 170 and 190 kbp, depending on the isolate. A conserved central region, of about 125 kbp is observed, but the ends of the stranded DNA are variable (Blasco et al., 1989) and the terminal areas show inverted repetitions (Sogo et al., 1984).

The complete DNA sequence of ASF virus, isolate BA71v was reported by Yánez et al. (1995). This isolate was shown to be 170,101 nucleotides long, containing 151 open-reading frames and encoding five multigene families.

Twenty-eight structural proteins have been identified in intracellular virus particles (Tabares et al., 1980) and 110 infectious proteins have been described in pig-infected macrophages, of which at least 50 have been shown to react with sera from infected or recovered pigs (Alcaraz et al., 1992). Some of these proteins (VP 73, VP 54, VP 30, VP 12) are very antigenic and are used as antigens for diagnostic techniques, but unfortunately no protection appears to be induced by them (Sanchez-Vizcaino, 1999).

ASF virus replicates predominantly in monocytes and macrophage cells (Malmquist and Hay 1960; Mínguez et al., 1988). Virus replication has also been observed in: endothelial cells (Wilkinson and Wardley, 1978), hepatocytes, renal tubular epithelial cells (Gomez-Villamandos et al., 1995) and neutrophils (Carrasco et al., 1996). No infection has been described in T or B porcine lymphocytes (Mínguez et al., 1988; Gomez-Villamandos et al., 1995). The ASF virus has also been adapted to grow in several stable cell lines such as VERO, MS and CV (Hess et al., 1965).

ASF virus is very resistant to low temperatures but a temperature of 56ºC for 70 minutes or 60ºC for 20 minutes can inactivate it. It is inactivated at a pH of less than 3.9, or more than 11.5, in serum-free medium; when serum or organic matter is presented resistance is increased. The ASF virus is also susceptible to inactivation by ether and choloroform and to several disinfectants such as sodium hydroxide, hypochlorites, chlorine, formalin, orthophenylphenol and iodine compounds.

ASF remains viable for long periods in blood, faeces and tissues. It may persist for several weeks or months in frozen or uncooked meat. In products prepared by curing (such as Parma ham), infectivity was not demonstrated in ham after 300 days of processing and curing (McKercher et al., 1987). In Spanish dry-cured meat products such as Serrano hams and Iberian hams and shoulder, the virus survives for 140 days in hams and for 112 days in loin meat (Mebus et al., 1993).

ASF virus can remain in an infectious state in the vector Ornithodoros ticks for months or occasionally years.

Disease(s) associated with this pathogen is/are on the list of diseases notifiable to the World Organisation for Animal Health (OIE). The distribution section contains data from OIE's Handistatus database on disease occurrence. Please see the AHPC library for further information from OIE, including the International Animal Health Code and the Manual of Standards for Diagnostic Tests and Vaccines. Also see the website: www.oie.int.

Host Animals

Vectors and Intermediate Hosts

References

Alcaraz C; Alvarez A; Escribano JM, 1992. Flow cytometric analysis of African swine fever virus-induced plasma membrane proteins and their humoral immune response in infected pigs. Virology (New York), 189(1):266-273; 42 ref.

Blasco R; Agüero M; Almendral JM; Vinuela E, 1989. Variable and constant regions in African swine fever virus DNA. Virology (New York), 168(2):330-338; 40 ref.

Breese S; De Boer CJ, 1966. Electron microscope observation of Africa swine fever virus in tissue culture cells. Virology, 28:420-428.

Carrasco L; Chacón-M de Lara F; Martín de las Mulas J; Gómez-Villamanods JC; Hervás J; Wilkinson PJ; Sierra MA, 1996. Virus association with lymphocytes in acute African swine fever. Veterinary Research, 27(3):305-312; 26 ref.

Gomez-Villamandos J; Hervas J; Mendez A; Carrasco L; Villeda C; Wilkinson P; Sierra M, 1995. Experimental African swine fever: apoptosis of lymphocytes and virus replication in other cells. J. Gen. Virol., 76:2399-2405.

Hess WL; Cox BF; Heuschele WP; Stone SS, 1965. Propagation and modification of African swine fever virus in cell cultures. Am. J. Vet. Res., 26:141-146.

Malmquist WA; Hay D, 1960. Hemadsorption and cytophathic effect produced by African swine fever virus in swine bone marrow and buffy coat cultures. Am. J. Vet. Res., 21:104-108.

McKercher PD; Yedloutschnig RJ; Callis JJ; Murphy R; Panina GF; Civardi A; Bugnetti M; Foni E; Laddomada A; Scarano C; Scatozza F, 1987. Survival of viruses in Prosciutto di Parma (Parma ham). Canadian Institute of Food Science and Technology Journal, 20(4):267-272; 13 ref.

Medbus CA; House C; Gonzalvo FR; Pineda JM; Tapiador J; Pire JJ; Bergada J; Yedloutschnig RJ; Sahu S; Becerra V; Sanchez-Vizcaino JM, 1993. Survival of foot-and-mouth disease, African swine fever, and hog cholera viruses in Spanish Serrano cured hams and Iberian cured hams, shoulders and loins. Food Microbiology, 10(2):133-143; 6 ref.

Mínguez I; Rueda A; Domínguez J; Sánchez-Vizcaíno JM, 1988. Double labeling immunohistological study of African swine fever virus-infected spleen and lymph nodes. Veterinary Pathology, 25(3):193-198; 25 ref.

Murphy F; Fauquet C; Bishop D; Ghabrial S; Harvis A; Martinelli G; Mayo M; Summer M, 1995. Virus taxonomy. Sixth report of the International Committee on taxonomy of viruses. Archives of Virology, Suplement 10.

OIE Handistatus, 2002. World Animal Health Publication and Handistatus II (dataset for 2001). Paris, France: Office International des Epizooties.

OIE Handistatus, 2003. World Animal Health Publication and Handistatus II (dataset for 2002). Paris, France: Office International des Epizooties.

OIE Handistatus, 2004. World Animal Health Publication and Handistatus II (data set for 2003). Paris, France: Office International des Epizooties.

OIE Handistatus, 2005. World Animal Health Publication and Handistatus II (data set for 2004). Paris, France: Office International des Epizooties.

OIE, 2005. African swine fever in Namibia. Follow-up report No. 1. Disease Information, 18(1).

Sanchez-Vizcaino JM, 1999. African swine fever. In: Leman AD, Straw BE, Mengeling WL, Dallaire S, Taylor DJ, eds. Diseases of swine. 8th edition. Iowa State University.

Sogo JM; Almendral JM; Talavera A; Vinuela E, 1984. Terminal and internal inverted repetitions in African swine fever virus DNA. Virology, 133(2):271-275; 14 ref.

Tabares E; Marcotegui MA; Fernandez M; Sanchez Botija C, 1980. Proteins specified by African swine fever virus I. Analysis of viral structural proteins and antigenic properties. Arch. Virol., 66:107-117.

Wilkinson PJ; Wardley RC, 1978. The replication of ASFV in pig endothelial cells. Br. Vet. J., 134:280-282.

Yánez RJ; Rodríguez JM; Nogal ML; Yuste L; Enríquez C; Rodriguez JF; Vinuela E, 1995. Analysis of the complete nucleotide sequence of African swine fever virus. Virology (New York), 208(1):249-278; many ref.

Distribution Maps