African Swine Fever Virus: A Review

Abstract

African swine fever (ASF) is a highly contagious viral disease of swine which causes high mortality, approaching 100%, in domestic pigs. ASF is caused by a large, double stranded DNA virus, ASF virus (ASFV), which replicates predominantly in the cytoplasm of macrophages and is the only member of the Asfarviridae family, genus Asfivirus. The natural hosts of this virus include wild suids and arthropod vectors of the Ornithodoros genus. The infection of ASFV in its reservoir hosts is usually asymptomatic and develops a persistent infection. In contrast, infection of domestic pigs leads to a lethal hemorrhagic fever for which there is no effective vaccine. Identification of ASFV genes involved in virulence and the characterization of mechanisms used by the virus to evade the immune response of the host are recognized as critical steps in the development of a vaccine. Moreover, the interplay of the viral products with host pathways, which are relevant for virus replication, provides the basic information needed for the identification of potential targets for the development of intervention strategies against this disease.

Keywords: A179L; ASFV; African swine fever virus; ER stress; apoptosis; autophagy; cellular responses; endocytosis; endosomal pathway; host cell targets; virus entry.

Figure 1

ASFV enters the host cell through a complex process involving dynamin- and clathrin-mediated endocytosis and macropinocytosis. Only few seconds later, ASFV progresses through the endocytic pathway and reaches mature endosomal compartments where viral decapsidation and fusion of the inner viral envelope with the endosomal membrane occurs. Newly synthesized virions are assembled in the viral factory and will exit the cell either by exocytosis budding at the plasma membrane or through the formation of apoptotic bodies.