Metagenomic Analysis of the Tonsil Virome Highlights Its Diagnostic Potential for Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is a chronic autoimmune disease whose exact pathogenesis remains unclear, despite links to genetics, environmental factors, and microbial dysbiosis. Recent studies have highlighted the role of the microbiome in RA, yet the contribution of the tonsil virome remains unexplored. This study aims to investigate whether changes in the tonsil virome are associated with RA progression and assess its diagnostic potential. Using metagenomic data from 32 RA patients and 30 healthy controls (HCs), we identified 45 782 viral operational taxonomic units (vOTUs), with 14 341 classified as core vOTUs. RA patients exhibited significantly reduced virome richness and diversity, whereas Siphoviridae and Microviridae dominated both groups. Statistical analysis identified 235 RA-associated viral markers, including 13 enriched in RA and 222 in HCs. RA-enriched markers were primarily bacteriophages infecting Streptococcaceae, whereas HCs displayed more diverse viral-host interactions. Random forest models demonstrated strong discriminatory power of viral markers in distinguishing RA patients from HCs, achieving an AUC of 0.960, outperforming bacterial markers. Correlation analyses further linked viral markers to immune cell subsets, suggesting that tonsil virome alterations may influence immune dysregulation in RA. This study reveals significant changes in the tonsil virome of RA patients, highlighting its potential as a diagnostic tool and offering new insights into RA pathogenesis. These findings pave the way for future research into the virome's role in autoimmune diseases and therapeutic development.