JC virus in cerebrospinal fluid samples of multiple sclerosis patients at the first demyelinating event

Objective To evaluate the possible involvement of IC virus (JCV) in the aetiology of multiple sclerosis (MS), through the comparison of DNA prevalences and viral loads of JCV in cerebrospinal fluid (CSF) of MS patients at the first demyelinating event and subjects suffering from other neurological diseases (OND). Methods Seventy-three CSF samples (43 from MS patients at the first demyelinating event, and 30 from patients with OND) were collected; all MS cases were followed up from 1 to 6.7 years after they were diagnosed with clinically definite MS. DNA was extracted and analysed by real-time PCR for the detection of JCV genomes. Results We found JCV DNA in the CSF of two MS patients (4.7%) with a mean viral load of 2.1 and 6.7 copies/mL of CSF. Among the patients of the OND group we did not find any positive sample. We did not find any difference in the course of the disease between MS patients with and without JCV genomes in their CSF along the follow up. Conclusion JCV seems to be only a bystander in the pathology of MS, and the presence of cell-free viral particles could be related to the immunological activation of the disease, mainly during relapses.