EBV reactivation priming of the peripheral immune system in multiple sclerosis relapse.

EBV reactivation in peripheral immune cells up to three months before MS relapse predicts disease exacerbation, with elevated viral transcripts and atypical B cell expansion.

• Why it matters: Understanding the cellular events leading to MS relapse is crucial for developing predictive markers and targeted therapies, yet these early immune changes remain poorly characterized.
• What they did: The study analyzed longitudinal blood samples from relapsing-remitting MS patients using single-cell RNA sequencing, flow cytometry, and RT-qPCR, identifying a pre-relapse signature linked to EBV reactivation.
• The result: Findings suggest EBV reactivation within a genetically susceptible immune environment acts as a proximal trigger for MS relapse, offering potential targets for early intervention and disease management.