African swine fever virus (ASFV) is an icosahedral virus with a double-stranded DNA genome of 170 to 190 kbp that causes a severe hemorragic disease in domestic pigs.  The knowledge of the complete sequence of the ASFV genome has provided new insights into the mechanisms of viral DNA replication and repair and has revealed the existence of viral defense molecules that play a key role in the interaction of the virus with its host.  Among these molecules, the virus codes for two proteins homologous to Bcl-2 and IAP, which are involved in the control of apoptosis.  In addition, ASFV proteins potentially able to interfere with the host immune response include a protein similar to the T cell adhesion molecule, CD2, a C-type lectin-like protein, and a homologue of cellular IkB that inhibits transcription factors NFkB and NFAT. Other viral genes with a role in virulence have been described.  Recent progress in the study of ASFV morphogenesis has come mainly from morphological analysis of cells infected with ASFV recombinants that inducibly express structural proteins.