The 25(OH)D levels could be involved in the regulation of EBV replication/reactivation in patients with MS.

The detection of the neurotropic variant in blood during natalizumab treatment could be critical in the prevention of the development of severe PML, since this variant appears simultaneously with the clinical symptoms of PML and mutates quickly.

We detected a viral reactivation in PBMCs and serum during the RTX treatment that did not seem to be influenced by either use of immunosuppressive drugs or the length of treatment with the monoclonal antibody. Although this reactivation was asymptomatic, the viral presence in blood could increase the probability of the appearance of a neurotrophic variant of JCV.

We found an association between health status measurement systems and severity index for OA and the levels of expression of HERV-K18. These results suggest the possible involvement of HERV-K18 in the aetiopathogenesis of the disease.