JC virus type 2B is found more frequently in brain tissue of progressive multifocal leukoencephalopathy patients than in urine from controls.

Objectives: Previous studies have shown that strains of human polyomavirus JC (JCV) of Asian origin (type 2) are much more highly represented in progressive multifocal leukoencephalopathy (PML) brain than would be expected from their frequency of excretion in urine samples of a comparable control group. The present studies were designed to test whether one subtype of type 2 was preferentially elevated.

Study design/methods: The statistical relation between JCV subtypes represented in PML brain tissue from 51 probands and those in urine samples from 115 control individuals was examined.

Results: The proportion of the JCV subtype 2B in PML brain (36%) was highly significantly increased relative to its occurrence in control urine samples (5.9%; P < .001). Type 1 and its subtypes were not different in the PML brain and control urine cohorts. The number of type 4 strains in PML brains was reduced, although the difference did not reach statistical significance (P = .08).

Conclusions: The results predict that the human immunodeficiency virus (HIV)-positive individuals at highest risk of PML infection are those carrying the JCV genotype known as type 2B. Prospective studies will be required to confirm this finding.