Japanese encephalitis virus hijacks the host purine biosynthetic network to promote viral replication in neurons.

Japanese encephalitis virus (JEV) is an important neurotropic orthoflavivirus that poses a threat to both human and animal health. However, the mechanism underlying its rapid replication in the central nervous system (CNS) remains poorly understood. In this study, we conducted metabolomic profiling of JEV-infected mouse brains and neurons, revealing a profound reprogramming of central carbon metabolism, particularly an enhancement in nucleotide synthesis. Integrated multi-omics analyses confirmed that JEV infection transcriptionally upregulates key enzymes involved in de novo purine biosynthesis (DNPB), one-carbon (1C) metabolism, and the pentose phosphate pathway (PPP) in neurons. Pharmacological inhibition of the core DNPB enzymes potently suppressed JEV replication in neurons and reduced both viral loads and neuroinflammation in JEV-infected mice, suggesting the essential role of DNPB in JEV replication within CNS. Mechanistically, we delineated the critical functions of both the non-oxidative PPP and MTHFD2-mediated 1C metabolism, which jointly supply essential precursors, such as ribose-5-phosphate and formyl groups, for the de novo biosynthesis of purines required for viral RNA replication. These findings unveil a strategy by which JEV co-opts the host's purine biosynthetic machinery to fulfill the nucleotide demands for its genomic replication, establishing DNPB and its supporting pathways as promising therapeutic targets for infections caused by JEV and other neurotropic viruses.