JC virus in the Irish population: significant increase of genotype 2 in immunocompromised individuals.

The human polyomavirus JC virus (JCV) is ubiquitous and can be shed in the urine of more than 40% of the healthy population. Amplification and sequencing of JCV from urine has allowed a distinctive map of the distribution of JCV genotypes worldwide. To define the frequency of JCV urinary excretion and genotype distribution in Ireland, urines from 121 healthy individuals and from 94 immunocompromised individuals (human immunodeficiency virus [HIV]-positive patients and rheumatoid arthritis patients) were collected. JCV DNA was detected by polymerase-chain reaction (PCR) with subsequent nucleotide sequencing of a fragment of the major capsid protein (VP1). JCV was detected in 20.7% of healthy individuals and was found significantly more often in the urine of HIV-positive patients (54.2%; P < .001) and rheumatoid arthritis patients (54.4%; P < .001). In healthy Irish individuals genotype 1 was the predominant genotype in 62.5%, followed by genotype 4 in 16.7% and genotype 2 in 12.5%. In contrast, genotype 2 was significantly more often isolated from the urine of both HIV-positive patients (60%) and rheumatoid arthritis patients (54.4%; P < .01). The pattern of genotype distribution among healthy Irish individuals is in agreement with data reported from other European countries, whereas the overall level of JCV urinary excretion is lower. Previous studies have found genotype 2 significantly more often in cerebrospinal (CSF) samples of patients with progressive multifocal leukoencephalopathy (PML). Here the authors report an increased frequency of genotype 2 in urine samples of immunocompromised non-PML patients. This finding further underlines the hypothesis that there could be biologic differences between JCV genotypes.