African Swine Fever Virus
Linda K. Dixon, Charles C. Abrams, Dave G. Chapman and Fuquan Zhang
from: Animal Viruses: Molecular Biology (Edited by: Thomas C. Mettenleiter and Francisco Sobrino). Caister Academic Press, U.K. (2008)
African swine fever virus (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. In common with other viral haemorrhagic fevers, the main target cells for replication are those of monocyte, macrophage lineage. 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 species with no disease signs. The virus encodes enzymes required for replication and transcription of the genome, including elements of a base excision repair system, structural proteins and many proteins that are not essential for replication in cells but have roles in virus survival and transmission in its hosts. Virus replication takes place in perinuclear factory areas. Assembly of the icosahedral capsid occurs on modified membranes from the endoplasmic reticulum. Products from proteolytically processed polyproteins form the core shell between the internal membrane and the nucleoprotein core. An additional outer membrane is gained as particles bud from the plasma membrane. The virus encodes proteins that inhibit signalling pathways in infected macrophages and thus modulate transcriptional activation of immune response genes. In addition the virus encodes proteins which inhibit apoptosis of infected cells to facilitate production of progeny virions. Viral membrane proteins with similarity to cellular adhesion proteins modulate interaction of virus-infected cells and extracellular virions with host components read more ...