Influence of TC virus coding region genotype on risk of multiple sclerosisand progressive multifocal leukoencephalopathy

Two features of the biology of JC virus make it a particularly suitable can didate for an agent in MS-like disease: its neurotropic capability targetin g glial cells as evidenced in progressive multifocal leukoencephalopathy le sions, and its capacity for latency and persistence as illustrated by its b ehaviour in the kidney. TC virus is chronically or intermittently excreted in the urine by some 40% of the population. The existence of TC virus in mu ltiple coding-region genotypes provides a unique approach to the study of J C virus-induced neurological disease. We have previously shown that a genot ype originating in Asia but also present in Europe and the US, called Type 2B, is more frequently found in PML brain than expected based on its preval ence in urine samples from a control population. In contrast, we find that the excretion of JCV in MS patients is similar in both genotype and frequen cy to that of control individuals, and appears to be regulated by factors u nrelated to those that control CNS disease activity.