The evolution of African swine fever virus in Sardinia (1978-2014) as revealed by whole-genome sequencing and comparative analysis.

African swine fever (ASF) is a highly contagious and lethal viral disease of pigs and wild boars, which is enzootic in many African countries and on the Italian island of Sardinia, where it has been present since 1978. Previous genetic analyses of Sardinian ASF virus (ASFV) isolates have revealed that they all belong to p72 genotype I, with only minor sequence variations. However, these studies examined only a few selected genes. To distinguish between these closely related isolates and better investigate ASFV evolution in Sardinia, we sequenced the complete genomes of 12 Sardinian ASFV isolates collected between 1978 and 2012, and compared them with 47/Ss/2008 and 26544/OG10. Most of the observed changes occurred in a time-dependent manner; however, their biological significance remains unclear. As a whole, our results demonstrate the remarkable genetic stability of these strains, supporting a single-source introduction of the virus.