Sotelo J et al. (2008) Varicella-zoster virus in cerebrospinal fluid at relapses of multiple sclerosis. Ann Neurol 63: 303–311

Previous studies have indicated that reactivation of latent varicella zoster virus (VZV) might be associated with relapse in patients with multiple sclerosis (MS). Sotelo et al. examined patients with a definite diagnosis of relapsing–remitting MS to determine the role of VZV in the exacerbation of this condition.

All cerebrospinal fluid (CSF) samples from 15 patients with MS who were in the first week of a clinical relapse had a high content of VZV DNA (mean 204,489 ± 26,782 copies/ml) and contained large numbers of viral particles that were morphologically identical to VZV. Samples from these patients were negative for all other types of herpesvirus. The quantity of VZV DNA was much lower in the CSF samples of 19 patients in remission from MS than in those in relapse.

Similarly, all patients in relapse, but few patients in remission, had VZV DNA in their peripheral blood mononuclear cells. All 10 patients examined longitudinally had VZV DNA in their blood samples during the first week of follow-up and 9 patients had VZV DNA in the second week; only 4 individuals tested positive for VZV DNA (in small amounts) after ≥40 days.

The authors conclude that the presence of VZV in the blood and CSF of patients with MS who are in relapse and the decrease during disease remission indicate a direct role for VZV in the pathogenesis of MS relapse.