Host-mediated SUMOylation of pE248R promotes African swine fever virus replication and virulence

SUMOylation, the covalent conjugation of small ubiquitin-like modifier (SUMO) proteins to lysine residues in target substrates, is an essential post-translational modification in eukaryotes. Recently, microbial manipulation of SUMOylation has emerged as an important virulence strategy for viruses. Here, we demonstrate that African swine fever virus CN/GS/2018 (ASFV CN/GS/2018) pE248R can be conjugated to SUMO1 and provide evidence that prevention of pE248R SUMOylation can block ASFV CN/GS/2018 infection. The E3 SUMO ligase PIAS4 interacts with pE248R via its SUMO interaction motifs (SIMs) and promotes pE248R SUMOylation at its lysine residues at positions 103 and 240. Additionally, PIAS4 can increase the stability of pE248R. Importantly, studies on ASFV CN/GS/2018 pE248R with mutations have shown that the SUMOylation sites, the SIMs, or both are essential for the viral replication cycle in vitro and that mutations in these regions attenuate the virus in swine. Collectively, these findings indicate that ASFV CN/GS/2018 pE248R SUMOylation is critical for ASFV CN/GS/2018 pathogenesis and virulence, thereby providing a potential strategy for ASF vaccine development. IMPORTANCE African swine fever virus (ASFV) poses a devastating threat to the global swine industry, yet effective vaccines and antiviral strategies remain unavailable. While microbial manipulation of host post-translational modifications is a common virulence strategy, how ASFV exploits the host SUMOylation machinery has remained elusive. Here, we demonstrate that ASFV CN/GS/2018 pE248R undergoes SUMO1 conjugation mediated by the E3 SUMO ligase PIAS4 via specific SUMO-interacting motifs, which enhances pE248R stability and is essential for the viral replication cycle and virulence in swine. Blocking pE248R SUMOylation at lysine residues 103 and 240 inhibits viral infection, revealing that ASFV CN/GS/2018 hijacks the host SUMOylation system as a critical pathogenesis mechanism. These findings identify a druggable virus-host interaction node and provide a rational target for developing next-generation attenuated ASFV vaccines.