African swine fever virus, illustration. This is the structure of the intracellular form of the virus. It consists of a core of double-stranded DNA (deoxyribonucleic acid) genetic material enclosed within a protein core shell that is itself enclosed in an inner lipid envelope. This structure is further enclosed in a protein capsid (green), which has protruding surface proteins that allow the virus to attach to its target cells. African swine fever virus causes African swine fever, a haemorrhagic fever in pigs that has a high mortality rate.