Origin, genomic diversity and evolution of African swine fever virus in East Asia

Since 2018, the outbreaks of genotype II African swine fever virus (ASFV) in China and several eastern Asian countries have caused a huge impact on the local swine industry, resulting in huge economic losses. However, little is known about the origin, genomic diversity, evolutionary features, and epidemiological history of the genotype II ASFV. Here, 14 high-quality complete genomes of ASFVs were generated via sequencing of samples collected from China over the course of 3 years, followed by phylogenetic and phylodynamic analyses. The strains identified were relatively homogeneous, with a total of 52 SNPs and 11 indels compared with the prototype strain HLJ/2018, among which there were four exceptionally large deletions (620-18,023 nt). Evolutionary analyses revealed that ASFV strains distributed in eastern Asia formed a monophyly and a 'star-like' structure centered around the prototype strain, suggesting a single origin. Additionally, phylogenetic network analysis and ancestral reconstruction of geographic state indicated that genotype II ASFV strains in eastern Asia likely originated from Western Europe. Overall, these results contribute to the understanding of the history and current status of genotype II ASFV strains in eastern Asian, which could be of considerable importance in disease control and prevention.