ASFV pE146L-induced ER remodeling is essential for viral replication.

African swine fever virus (ASFV) causes a severe hemorrhagic disease, posing a significant threat to the global pig industry. Although the ASFV encodes nearly 200 proteins, the functions of many remain unknown. Here, we identify the inner envelope protein pE146L as essential for ASFV replication. pE146L, localized in the endoplasmic reticulum lumen, induces endoplasmic reticulum (ER) perinuclear aggregation, and its absence disrupts viral factory formation. Mechanistic studies revealed the first high-resolution crystal structure of pE146L-ΔTM. Structural and biochemical analyses revealed that disrupting the intermolecular disulfide bonds of the dimers (C103A) abrogates ER aggregation and impedes viral replication. Furthermore, pE146L binds lipids via a positively charged surface patch, a function critical for replication, suggesting a role in lipid regulation. These findings highlight the multifunctionality of pE146L in ASFV morphogenesis and provide a promising target for anti-ASFV drug development.

Importance: African swine fever virus (ASFV) causes a highly lethal infectious disease in swine; however, our understanding of its replication and assembly mechanisms remains limited, which hinders the development of vaccines and drugs. In this study, we identified the uncharacterized pE146L, a protein of the inner envelope that is required for the viral life cycle. Notably, we found that pE146L showed distinct colocalization and the ability to induce noticeable ER aggregation. Moreover, we solved the first high-resolution crystal structure of the extracellular soluble region of pE146L and discovered that it is a lipid-binding protein. Interestingly, structural and biochemical analyses suggest the potentially significant impact of intermolecular disulfide bonds on ER aggregation and viral replication. These results highlight the multifunctionality of ASFV pE146L, providing new insights for the development of specific antiviral drugs.