The John Cunningham virus (JCV) is a polyoma virus that infects humans mainly in childhood or adolescence, and presents no symptomatic manifestations. JCV can cause progressive multifocal leukoencephalopathy (PML) in immunosuppressed individuals, including those undergoing treatment for multiple sclerosis (MS) and neuromyelitis optica (NMO). PML is a severe and potentially fatal disease of the brain. The prevalence of JCV antibodies has been described to be between 50% and 90% in human serum. The aim of the present study was to review worldwide data on populations of patients with MS and NMO in order to establish real-life values of JCV seropositivity in these individuals.
The present review followed the PRISMA guidelines using the following search terms: "JCV" OR "JC virus" AND "multiple sclerosis" OR "MS" OR "NMO" OR "neuromyelitis optica" AND "prevalence". These terms were searched for both in smaller and in larger clusters of words. The databases searched included PubMed, Medline, SciELO, LILACS, Google Scholar and EMBASE.
After initial selection, 18 papers were included in the review. These articles reported on the prevalence of JCV antibodies in serum of patients with MS or NMO living in 26 countries. The systematic review identified data on over 29,000 patients with MS/NMO and found overall that 57% of them (16,730 individuals) were seropositive for anti-JCV (range 40% to 69.5%).
The median worldwide prevalence of JCV among adults with MS or NMO was 57%.
If the incidence of JCV was 100% it could form a good potential to be a target as CD8 and antibody depletion of infected oligodendrocytes but this study suggests it is too low. But at about 60% it is reasonably common that your chances of being positive are high and this will limit your treatment options.
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