The evolving landscape of African swine fever: the game-changing impact of recombinant genotype I/II on Asia–Pacific control strategies

The emergence of genotype I/II recombinant African swine fever virus (rASFV) in the Asia–Pacific region represents a significant shift in the molecular epidemiology of the ongoing ASF panzootic. Following the PRISMA-ScR framework, this study synthesizes sources of evidence from China, Vietnam, Russia, and Taiwan published between 2021 and 2025. Four electronic databases and relevant gray literature were included in the review. The evidence indicates that “JS/LG/21-like” recombinant strains exhibit a stable chimeric genome architecture, comprising a genotype I backbone incorporating genotype II-associated virulence determinants, including EP402R and members of the MGF_505/360 gene families. This genomic mosaicism appears to confer a synergistic phenotype characterized by high lethality and preserved hemadsorption (HAD+) activity, exceeding the typically lower virulence profile of ASF genotype I lineages. The research further identifies key systemic vulnerabilities. First, diagnostic platforms relying primarily on genotype II-specific primers may lead to misclassification or under-detection of recombinant strains. Second, existing genotype II-targeted vaccine candidates exhibit limited cross-protective immunity against rASFV. Comparative genomic analyses demonstrate extremely high nucleotide identity (>99.9%) across affected regions, supporting the hypothesis of a monophyletic evolutionary profile followed by rapid clonal expansion. These findings highlight the urgent need to update diagnostic platforms, expand high-resolution genomic surveillance (e.g., whole genome sequencing), and integrate sylvatic cycle dynamics into routine monitoring frameworks. Strengthened policy coordination and One Health-oriented strategies are essential to mitigate the sustained regional transmission and ecological entrenchment of these stabilized recombinant lineages.