Classical swine fever virus hijacks triglyceride metabolism via the NS5B-PLIN5 axis to facilitate viral replication.

Classical swine fever virus (CSFV) represents a critical pathogen that causes substantial economic losses to the swine industry and heavily relies on host lipid metabolic reprogramming during infection. However, the detailed regulatory mechanisms governing CSFV-induced lipid metabolic remodeling remain poorly understanding. In this study, we systematically investigated how CSFV reprograms lipid metabolism to facilitate viral replication. Our results demonstrated that CSFV infection significantly promotes the accumulation of triglycerides (TG), phosphatidylethanolamine (PE), and phosphatidylglycerol (PG), with pathway enrichment analysis revealing pronounced activation of cholesterol metabolism and autophagy pathways. Administration of autophagy inhibitor chloroquine resulted in prominent alterations in TG metabolites, with integrative analyses demonstrating that TG constituted 56.36% of the shared differential metabolites, underscoring the pivotal role of TG metabolism in CSFV infection. Notable, the lipid droplet-associated protein Perilipin 5 (PLIN5) was significantly upregulated following CSFV infection, and the viral nonstructural protein NS5B was found to directly interact with PLIN5 and promote its expression. Functional assays revealed that CSFV RNA localizes to lipid droplets, and overexpression of PLIN5 significantly enhanced viral replication. Collectively, this study uncovers a mechanism by which CSFV hijacks TG metabolism through the NS5B-PLIN5 axis and exploits lipid droplets as platforms for viral replication.