Lipophagy fuels phosphatidylcholine synthesis for Newcastle disease virus replication

Lipid droplets (LDs) are dynamic organelles that store neutral lipids and maintain lipid homeostasis. Many viruses exploit LDs as replication platforms or lipid sources, but their role in supplying membrane lipids for viral assembly remains unclear. Newcastle disease virus (NDV), an enveloped RNA virus with oncolytic potential, extensively remodels host metabolism, yet its impact on LD lipid mobilization is unknown. Here, we show that NDV reprograms host lipid metabolism via SQSTM1/p62-dependent lipophagy, selectively degrading triglycerides (TAGs) enriched in unsaturated fatty acids (UFAs). Lipidomics revealed concurrent depletion of UFA-containing triglycerides (UFA-TAGs) and UFA-containing phosphatidylcholines (UFA-PCs) during infection. Inhibition of lipophagy blocked LD degradation, reduced viral replication, and suppressed UFA-PC formation. Isotope tracing demonstrated that lipophagy-derived UFAs are incorporated into phosphatidylcholines (PCs) via the Kennedy pathway, whereas β-oxidation was dispensable. UFA supplementation rescued viral replication under lipophagy blockade and promoted virus-like particle (VLP) release, indicating that UFA-PCs facilitate viral budding. These findings uncover a distinct NDV strategy linking lipophagy-driven UFA release to phospholipid synthesis and membrane remodeling, revealing a lipid-based metabolic vulnerability for antiviral and oncolytic interventions.Abbreviations: AP: autophagosome; ATG: autophagy related; ATP: adenosine triphosphate; CQ: chloroquine; EGFP: enhance green fluorescent protein; FFA: free fatty acid; HN: Hemagglutinin-Neuraminidase; LA: linoleic acid; LD: lipid droplet; LIPA: lipase A, lysosomal acid type; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; NDV: newcastle disease virus; NP: nucleoprotein; OA: oleic acid; PA: palmitic acid; PC: phosphatidylcholine; PLIN2/ADRP: perilipin 2; PNPLA2/ATGL: patatin like phospholipase domain containing 2; POA: palmitoleic acid; SFA: saturated fatty acid; TAG: triglyceride; UFA: unsaturated fatty acid; UFA-PC: UFA-containing phosphatidylcholine; VLP: virus-like particle.