Objective To investigate the characteristics of salivary and supragingival plaque viromes in patients with metabolic dysfunction-associated fatty liver disease (MAFLD), and provide new insights for noninvasive oral screening and ecological intervention for MAFLD.

Methods This study included 21 MAFLD patients and 20 healthy controls. Saliva and supragingival plaque samples were collected, and metagenomic sequencing was used to analyze the characteristics of the oral virome.

Results The α-diversity and β-diversity of the salivary virome did not differ significantly between MAFLD patients and healthy individuals (P > 0.05). However, compared with healthy individuals, the α-diversity (Shannon index) and β-diversity (Bray–Curtis distance) of the supragingival plaque virome showed significant differences (P = 0.0303, P = 0.001). For species with a relative abundance greater than 0.1%, 14 viral species in saliva and 5 in supragingival plaque differed significantly in relative abundance between the two groups (P < 0.05), with multiple Streptococcus phages enriched in the saliva of MAFLD patients. LEfSe and random forest analyses identified potential biomarkers in saliva and supragingival plaque. Receiver operating characteristic (ROC) curve analysis showed strong diagnostic performance for these biomarkers in both saliva (area under the curve AUC = 0.9548, 95% CI: 0.8898-1.0000) and supragingival plaque (AUC = 0.8952, 95% CI: 0.7774-1.0000). Spearman correlation analysis revealed associations between viral species in saliva or supragingival plaque and various disease indicators (P < 0.05). Compared with healthy individuals, MAFLD patients showed higher node counts, significant relationship numbers, and average node degrees in the co-occurrence networks of salivary and supragingival plaque viromes.

Conclusion Differences in the species composition and structure of the oral virome between MAFLD patients and healthy individuals suggest that oral viral species could serve as potential biomarkers for diagnosing MAFLD.