Vientovirus capsid protein mimics autoantigens and contributes to autoimmunity in Sjögren's disease.

Viral infections are implicated in the pathogenesis of autoimmune diseases, including Sjögren's disease (SjD), but the mechanisms linking viral antigens to disease development remain poorly understood. To address this, we conducted shotgun metagenomic sequencing of saliva samples from 35 patients with SjD and 25 healthy controls. The salivary virome of the patients with SjD, particularly those with high disease activity, had an expansion of Siphoviridae bacteriophages and increased eukaryotic viral sequences, including Vientovirus. This virus was associated with lacrimal gland dysfunction and elevated anti-SSA/Ro52 autoantibody levels. Alignment analysis and cross-blocking assay identified molecular mimicry between the Vientovirus capsid protein and the autoantigen SSA/Ro52. Mice immunized with a Vientovirus capsid peptide developed anti-SSA/Ro52 antibodies and showed immunological features resembling those of patients with SjD. These findings highlight distinct virome profiles in SjD and provide mechanistic evidence supporting the role of Vientovirus in triggering autoimmunity through molecular mimicry.