Fig. 1.

JC viremia and viruria in 15 RRSM patients during the first 12 months of natalizumab treatment (follow-up <12 months). Serial urine and plasma samples were performed at t0 (baseline: 0 natalizumab infusions) and every 4 months for 1 year (t1: 4 infusions; t2: 8 infusions; t3: 12 infusions). There was no statistically significant difference between JC viremia values recorded at t0 and the other values observed at each time of follow-up. On the other hand, JC viruria values observed at t2 were significantly higher than those observed at t0. Finally, at each time of follow-up, the JC viremia values were always significantly lower with respect to the JC viruria values. Statistical analysis was performed using nonparametric tests and significance was set for a p value <0.05