* 78 urine, 78 plasma and 78 PBMCs samples were collected at baseline (t0) and after 4 (t1), 8 (t2), and 12 (t3) months of therapy.
† 2-step virus-like particle-based enzyme-linked immunosorbed assay (ELISA) (STRATIFY JCV®) was performed at t0 and t3, to detect specific anti-JC virus antibodies in serum of the 21 enrolled subjects.
** JCPyV loads values are expressed as log10 genome equivalent (gEq)/mL in urine and in plasma, and as log10 gEq/106 cells in PBMCs and they are indicated in boldface.
§ By χ2 test: positive STRATIFY JCV® patients after 1-year of natalizumab treatment vs negative STRATIFY JCV® patients after 1 year of natalizumab treatment. p value < 0.05 only for JCPyV DNA positive urine samples.
‡ patient MS2 suspended natalizumab for allergic reaction; patients MS19 and MS20 showed poor compliance; patient MS18 suspended the biological therapy for uterine cancer and papillomatosis after 11 months of natalizumab infusions; patient MS4 did not perform 2 natalizumab infusions because of Escherichia coli urinary infection; patient MS5 showed clinical relapse during follow up.