Untargeted metabolomics reveals remodeling of hepatic metabolic networks and potential tumor-associated metabolic signatures induced by ALV-J in Luhua chickens.

Avian leukosis virus subgroup J (ALV-J) represents a major pathogen that severely threatens the poultry industry. The liver contains abundant sinusoidal blood vessels with slow blood flow, which facilitates the enrichment and replication of viral particles; it serves as the primary target organ of ALV-J and the site with the highest tumor incidence. Nevertheless, the hepatic metabolic alterations triggered during ALV-J infection and their potential links to disease progression remain poorly understood. This study aimed to characterize the hepatic metabolic remodeling profile of Luhua chickens upon ALV-J infection using untargeted metabolomics. One-day-old Luhua chickens were divided into an ALV-J-infected group and a control group. Liver tissues were harvested at 60 days post-infection (dpi), and untargeted metabolomic profiling was performed via liquid chromatography-tandem mass spectrometry (LC-MS/MS). Differential metabolites and perturbed metabolic pathways were identified through multivariate statistical analysis and KEGG pathway enrichment analysis. In total, 434 differential metabolites were identified, including 241 metabolites detected in the positive ion mode and 193 metabolites in the negative ion mode. Pathway enrichment analysis revealed that carbon metabolism (rich factor = 0.060, P = 0.042) and oxidative phosphorylation (rich factor = 0.050, P = 0.021) exhibited the strongest enrichment, followed by biosynthesis of amino acids, tricarboxylic acid (TCA) cycle, riboflavin metabolism and glutathione metabolism. Further annotation of differential metabolites demonstrated that succinate and fumarate, two TCA cycle intermediates positioned at the crossroad of carbon metabolism and oxidative phosphorylation, were significantly accumulated in the infected group. Preliminary transcriptional analysis of key metabolic enzyme genes within these pathways, including SDHB, FH, GLS2, ASL and PC, showed that only ASL was significantly upregulated, while the remaining genes displayed no significant differences. This finding implies that metabolite accumulation may not be fully governed at the transcriptional level. In summary, ALV-J infection triggers extensive hepatic metabolic remodeling centered on the reprogramming of carbon metabolism and oxidative phosphorylation. This study, for the first time in an avian model, identified the alterations of succinate and fumarate as potential tumor-associated metabolic signatures. These findings provide novel mechanistic insights into the metabolic basis underlying hepatic pathological progression induced by persistent ALV-J infection. The identified key metabolites and pathways also supply candidate targets for developing early disease warning and metabolic intervention strategies. Longitudinal investigations and functional assays are warranted in future work to further validate the direct contribution of these metabolic shifts to ALV-J-associated tumorigenesis.