Journal of Medical Virology 79:408–412 (2007)

Presence, Quantitation and Characterizationof JC Virus in the Urine of ItalianImmunocompetent Subjects

Andrea Rossi,1 Serena Delbue,1,2 Romina Mazziotti,1 Marilena Valli,1

Elisa Borghi,1 Roberta Mancuso,1 Maria G. Calvo,1 and Pasquale Ferrante1,2*1Laboratory of Molecular Medicine and Biotechnology, Don C. Gnocchi Foundation ONLUS, IRCCS, Milano, Italy2Department of Biomedical Science and Technology, University of Milan, Milano, Italy

Human polyomavirus JC (JCV) infects the world-wide population, remains latent in the kidney,and is excreted in the urine. A longitudinal studywas performed in order to evaluate JCV excre-tion, to characterize molecularly the virus and todetermine if its presence in urine is a conse-quenceof viral reactivationormerely of epithelialsquamous cell shedding. Thepresence of cellularsediment and the JCV genome were examinedin 333 urine samples collected periodically for3 months from 17 healthy subjects; molecularcharacterization, and quantitation of the viruswere also undertaken. JCV DNA was detectedin 40.2% of the samples, with a significantdifference (P< 0.001) observed between malesand females. JCV shedding was independent ofthe presence of cellular sediment in everyindividual. JCV genotype 1 was the genomedetected most frequently, while all of the ampli-fied strains showed archetypal organization ofthe transcriptional control region (TCR). Noclinical symptoms have been associated withJCV excretion and no microbial load wasdetected in the urine samples. The lack ofcorrelation between JCV DNA detection and thepresence of squamous cells in urine sedimentindicates that viruria is regulated by the life cycleof JCV. Thus, the virus is eliminated as conse-quence of its reactivation. J. Med. Virol.79:408–412, 2007. � 2007 Wiley-Liss, Inc.

KEY WORDS: JC virus (JCV); urine; cells;urinary sediment

INTRODUCTION

JC virus (JCV) is ubiquitous in humans and infectsmore than 90% of the worldwide adult population[Walker and Frisque, 1986], with primary infectionoccurring in childhood. Primary infection is usuallyasymptomatic, although specific symptoms were some-times observed [Reploeg et al., 2001].

After primary infection, JCV persists in the kidney,while lymphoid tissue and the central nervous system(CNS) [Dorries et al., 1994; Kitamura et al., 1994] havebeen indicated as possible sites of latency. In subjectswith immunodeficiency, such as patients with AIDS,patients with cancer or transplant recipients, JCV canreactivate and infect the oligodendrocytes, causingprogressive multifocal leukoencephalopathy (PML), afatal demyelinating disease of the CNS [Hou andMajor,2000]. Occasionally, JCV can produce pathologicaleffects in the kidney [Randhawa et al., 2001; Boldoriniet al., 2003], but most often, when reactivation occursin healthy people, it leads to asymptomatic viruria[Kitamura et al., 1990]. Boldorini et al. [2005] describedthe random localization of the virus in its latent stateboth in the kidney and in the urinary tract.

Several studies focused on the epidemiology andmolecular characterization of JCV in urine collectedfrom PML patients and healthy subjects from variouscountries. Based on the analysis of a fragment ofthe viral protein 1 (VP1) coding sequence [Stoneret al., 2000; Agostini et al., 2001a], the most frequentgenotypes described up to now are genotypes 1 and 4 inEurope [Pagani et al., 2003], genotypes 2 and 7 in Asiaand genotypes 3 and 6 in Africa [Agostini et al., 2001b].

The transcriptional control region (TCR) of the virushas a central role in viral replication and the archetypalform is found in urine, while the rearranged patternscould generate variants with altered tissue tropism andpathogenic capability [Elsner and Doerries, 1998;Ciappi et al., 1999; Vaz et al., 2000].

Grant sponsor: NIH; Grant number: R01 MH072528-02; Grantsponsor: Italian Institute of Health to Don Gnocchi Foundation,IRCCS.

*Correspondence to: Pasquale Ferrante, MD, Laboratory ofMolecular Medicine and Biotechnology, Don C. Gnocchi Founda-tion, IRCCS, Via Capecelatro, 66, 20148, Milan, Italy.E-mail: pferrante@dongnocchi.it

Accepted 18 October 2006

DOI 10.1002/jmv.20829

Published online in Wiley InterScience(www.interscience.wiley.com)

� 2007 WILEY-LISS, INC.

The prevalence of JCV urinary excretion over time inimmunocompetent subjects is not well established, and,because of the possible pathogenic role in humans, itis of interest to define the pattern of viral excretionin healthy individuals. A longitudinal study wasperformed by collecting periodically urine samples fromhealthy Italian subjects in order to evaluate JCVpresence, viral load, molecular organization, and urinesediment, and to verify whether the presence of JCV inthe urine is due to a process of viral activation or if thevirus is merely carried by epithelial squamous deadcells, where it is latent.

MATERIALS AND METHODS

Subjects

Three hundred and thirty-three samples werecollected from 17 individuals with a mean of 20 samplesper subject. The subjects include 9 females (mean age:47 years old; range: 40–60 years old) and 8males (meanage: 49 years old; range: 38–74 years old) living inNorthern Italy. Urine was periodically collected for3 months. None of the subjects were exposed topharmacological therapy, and none of the women werepregnant.

Urine Clinical Analysis

Physical and chemical analysis of the urine sampleswere performed (Super Aution Analyzer SA4220,MENARINI Diagnostic, Italy). Microscopic examina-tion of the urinary sediment was carried out on freshsamples. Collected samples were centrifuged at 4,000gfor 10 min, the supernatants were discarded and thesediment was subjected to microscopic observation. Theelements thatweremonitoredwere:white and red bloodcells, epithelial cells, crystals (uric acid, calciumoxalate,and urates), microbial load, cylinders (hyaline, granu-lar, hematic, leucocytosis) and mucus.

JCV DNA Detection and MolecularCharacterization of VP1 and TCR Regions

Urine samples were treated according as describedpreviously [Agostini et al., 1995]. The presence of JCVDNA was examined in the urine pellet by means of anested polymerase chain reaction (PCR), designed toamplify the large T antigen (LT) coding region. Theprimers and conditions for this analysis were describedin a previous study [Ferrante et al., 1995].

Part of the JCV genome that was found in the urinesamples was characterized molecularly by performingamplification and nucleotide automatic sequencing ofthe VP1 and TCR regions, as previously described[Pagani et al., 2003; Delbue et al., 2005a]. Sequencehomology searches were performed with BLAST atNCBI according to Agostini et al. [1996] for JCVgenotyping, and Jensen and Major [2001] for JCV TCRorganization.

Real-Time PCR

Viral load of JCV DNA was determined using aTaqMan PCR strategy. Detection was performedusing an ABI PRISM 7000 Sequence Detection System.Real-time PCR (rt-PCR) assay used specific primerstogether with a fluorescent TaqMan probe (PE AppliedBiosystems, Cheshire, UK) to detect a 54 bp amplicon inthe LT region, as described previously [Delbue et al.,2005b].

Statistical Analysis

Statistical evaluations were done using the t-test(EpiInfo 6.0).

RESULTS

Sediment Analysis

Three hundred and thirty-three urine samples weretested and classified on the basis of the number of cellsdetected by microscopic observation into six differentgroups termed A–F. For all collected urine samples,cells were epithelial and no decoy cells were identified;no alteration in the physical-chemical parameters or asignificant presence ofmicrobial flora has been observed(data not shown).Most of the urine samples did not havecells in the sediment and belonged to class A (Table I).The shedding of epithelial cells was significantly loweramong male than female subjects and most of theurine samples collected from males belonged to class A(136 males vs. 86 females, P<0.001; Table I).

JCV DNA Detection

PCR analysis was undertaken on all urine samplesand JCV DNA was detected in 134 out of 333 samples(40.2%); it was found in urine samples collected from5 males, with a total of 85 JCV positive samples and3 females, with a total of 49 JCV positive samples. Thedata showed ahigher number of JCVpositive samples inthe male group (53.1%) compared to the femalegroup (28.3%), with a significant statistical difference(P< 0.001). The distribution of JCV DNA was differentin the 6 classes of samples (Table II): 43.2% of thesamples were in class A, 36.8% in class B, 30.4% in class

J. Med. Virol. DOI 10.1002/jmv

TABLE I. Distribution of Urine Samples, Collected From8 Male and 9 Female Healthy Volunteers, Within the Classes,

Based on Analysis of Cellular Sediment

Cell class Urine samples Males Females

A 222 136** 86**B 57 12** 45**C 23 6* 17*D 15 1* 14*E 13 4 9F 3 1 2Total 333 160 173

Cells class: A¼0 cells; B¼1–10 cells; C¼ 10–20 cells; D¼ 20–30 cells;E¼ 30–60 cells; F¼ 60–100 cells.*P< 0.05.**P< 0.001.

JCV Excretion in Healthy Italian Population 409

C, 13.3% in class D, 38.5% in class E, and all of thesamples (3/3) in classFwerepositive for JCV.Among thefemale group, a reduction of JCV presence correlatedwith an increase in cellular excretion (P<0.05).

JCV DNA Quantitation

To evaluate the relationship between the presence ofcells in the urinary sediment and viral excretion, aquantitative assay on the samples of three individualswith significant cellular excretion was carried out. Inthe first patient, the mean JCV viral load was 5.87Eþ09 copies/ml, (range 0–4.69Eþ10 copies/ml), in thesecond patient the mean viral load was 3.43Eþ07 copies/ml (range: 0–2.24Eþ08 copies/ml) and in thethird patient the mean viral load was 3.84Eþ07 copies/ml (range: 0–2.48Eþ08 copies/ml) (Fig. 1).

Identification of JCV Genotypesand of the TCR

The distribution of JCV genotypes was investigatedby automatic sequencing analysis of part of the VP1coding region amplified from urine samples that weredetermined previously to be positive for JCV LT DNA.Genotype 1, amplified in 62.5% (5/8) of the patientswith JCV positive urine, was the predominant variant;3 subtypes of 1A and 2 subtypes of 1B were identified.JCV genotype 2 was found in 25% (2/8) of the patients,and one subject presentedwith genotype 4, with a stablepoint mutation (C!G) at nt 1851 (#408). The dataobtained by sequencing analysis of the JCV TCRshowed the presence of the archetype organization (IS)in all the sequences found in the urine samples (data notshown).

DISCUSSION

JCV is present in the worldwide adult population. Itpersists in the kidney of the host, and reactivates in bothimmunocompromised subjects and in healthy indivi-duals [Polo et al., 2004]. JCV reactivation in normalhosts is not associated with renal damage or lysis of thecells and the excretion of the virus in the urine does notcause any clinical symptom. However, data regardingthe excretion pattern of the virus in the normal

population are still lacking and little is known aboutviral reactivation and shedding over time.As of now, it isnot clear whether the excreted virus is carried by theepithelial cells or if JCV shedding is a consequence ofviral reactivation. In order to define better the pattern ofJCV excretion over time in the healthy population,urine samples were periodically collected from healthyvolunteers and analyzed to characterize the viralstrain and to correlate JCV shedding with the presenceof cellular debris. The percentage of JCV positive urinesamples confirmed data from a previous study on anItalian population [Pagani et al., 2003]; there was ahigher frequency of JCV positive urine frommales thanfemales. On the contrary, males had a lower frequencyand lowernumber of cells in theurinary sediment. Thus,by comparing the random presence of JCV and thefrequency of urinary cells, it seems that viral shedding isnot related to the presence of cells in the urine sedimentand that JCV DNA is not carried by dead epithelialcells, but is independently excreted. Moreover, amongfemales it has been observed that the rate of JCVpresence decreased when the amount of cells increased,confirming the lack of association between these twoparameters.

All JCV-positive subjects were continuous excreters,based on the definition by Polo et al. [2004], suggestingthat viral replication does not occur sporadically.Continuous reactivation and shedding may increasethe possibility of viral transmission inside the healthypopulation. In fact, JCV is probably transmitted fromparents to children and acquired by horizontal trans-mission, involving both the family and community[Zheng et al., 2004].

Data from a quantitative analysis of JCV load werecompared with the number of cells and other urinaryparameters. This analysis showed that viral excretion isindependent of both the presence and amount of cellsand the microbial flora. The amount of excreted virusvaried, alternating peaks of increased and decreasedviral load within a subject. The viral load was alsodifferent in every subject. Therefore, as previouslysuggested [Dorries, 2001], JCV can maintain persistentand silent infection status without clinical signs inimmunocompetent individuals, even when virus ex-cretion is high.

J. Med. Virol. DOI 10.1002/jmv

TABLE II. Distribution of JCV Positive Urine Samples Within the Defined Cellular Classes

Cells class

JCVþ samples

Urine samples Males Females

A 96/222 (43.2%) 69/136 (50.7%)** 27/86 (31.4%)**B 21/57 (36.8%) 7/12 (63.6%) 14/45 (36.4%)C 7/23 (30.4%) 5/6 (83.3%)* 2/17 (11.8%)*D 2715 (13.3%) 1/1 (100%) 1/14 (7.1%)E 5/13 (38.5%) 2/4 (50%) 3/9 (33.3%)F 3/3 (100%) 1/1 (100%) 2/2 (100%)Total 134/333 (40.2%) 85/160 (53.1%)** 49/173 (28.3%)**

Cells class: A¼0 cells; B¼1–10 cells; C¼ 10–20 cells; D¼ 20–30 cells; E¼30–60 cells; F¼ 60–100 cells.*P< 0.05.**P< 0.001.

410 Rossi et al.

The same genotype and archetypal organizationof the TCR were conserved over time in a givensubject, indicating that the shed virus usually resultsfrom a JCV infection acquired in childhood, ratherthan from repeated infections with different strains[Yogo and Sugimoto, 2001]. Genotyping analysis of theVP1 coding region confirmed that genotype 1 is themost frequently detected genome in the Italian popula-tion, followed by JCV genotype 2 and type 4, asreported previously [Agostini et al., 2001a; Paganiet al., 2003].

In conclusion, the data from the study showed thatJCV urinary excretion is common in healthy subjects,with ahigher frequency inmales than females. The viralsheddingpattern changesamong individuals due toJCVreplication anddoesnot correlatewith cellular excretionin urinary sediment. Given the ubiquitous presenceof JCV and its ability to remain in a latent state in thekidney, it could be interesting to study the localfactors that stimulate or inhibit JCV reactivation inimmunocompetent hosts, and to understand better itspathogenicity.

J. Med. Virol. DOI 10.1002/jmv

Fig. 1. Sediment analysis (gray rectangle) and viral loads (black line) of urine samples collected duringthe period February 2003–June 2003 from three patients excreting JCV.

JCV Excretion in Healthy Italian Population 411

ACKNOWLEDGMENTS

This work was partially supported by NIH Grantnumber R01 MH072528-02 to P.F. and by the NationalProgram of Research on AIDS 2004 from the ItalianInstitute of Health to Don Gnocchi Foundation, IRCCS.

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