Journal of Medical Virology 85:2016–2019 (2013)

Detection of Merkel Cell Polyomavirus in OralSamples of Renal Transplant Recipients WithoutMerkel Cell Carcinoma

Camila Freze Baez,1 Maria Angelica A. M. Guimaraes,2 Rosangela A. G. Martins,3

Ana Carolina Jonard Zalona,2 Joao Jose Cossatis,1 Mariano Gustavo Zalis,2

Silvia Maria Baeta Cavalcanti,1 and Rafael Brandao Varella1*1Department of Microbiology and Parasitology, Fluminense Federal University, RJ, Brazil2Department of Preventive Medicine, Faculty of Medicine, Federal University of Rio de Janeiro, RJ, Brazil3Division of Research, University Hospital Clementino Fraga Filho, Federal University of Rio de Janeiro, RJ, Brazil

Merkel cell carcinoma (MCC) is a rare butaggressive neuroendocrine cancer, with ap-proximately 80% of cases associated withMerkel cell polyomavirus (MCPyV). The lack ofinformation concerning its occurrence in non-MCC immunosuppressed populations led tothe investigation of MCPyV DNA in saliva andoral biopsies from 60 kidney allograft recipi-ents and 75 non-transplanted individuals (con-trol group). In contrast to herpesviruses, whichwas also investigated (CMV, HHV-6A, and B,HHV-7) MCPyV was detected predominantly inpatients with oral lesions (gingivitis and/orperiodontitis) of both transplanted and non-transplanted groups (P ¼ 0.016) and in thesaliva of the transplanted group (P ¼ 0.009).MCPyV co-detection with CMV (P ¼ 0.048), andHHV-6 (P ¼ 0.020) in the saliva of transplantedpatients requires further investigation on apossible role of co-infection. J. Med. Virol.85:2016–2019, 2013.# 2013 Wiley Periodicals, Inc.

KEY WORDS: Merkel cell polyomavirus; oralcavity; kidney transplantation

INTRODUCTION

Merkel cell polyomavirus (MCPyV) was discoveredin 2008 using digital transcriptome subtraction in upto 80% of Merkel cell carcinomas (MCC) and hasbeen proposed as the etiologic agent of this neuroen-docrine neoplasia [Feng et al., 2008]. This malignan-cy is more frequent among elderly andimmunosuppressed individuals, including organ re-cipients [Penn and First, 1999; Harwood et al., 2003].In the latter, the immunosuppressive therapy re-quired to prevent allograph rejection also creates a

permissive environment for opportunistic viral infec-tions [Fishman and Rubin, 1998], such as herpesvi-ruses and polyomaviruses [Comoli and Ginevri,2011].In the healthy population, MCPyV seroprevalence

may range from 25% to 42% [Kean et al., 2009].The virus has been detected in several tissues,including the upper aerodigestive and genitourinarytracts and skin with and without MCC [Foulongneet al., 2010; Loyo et al., 2010]. However, quantita-tive studies have found higher MCPyV loads in theoral cavity in comparison to other tissues, whichmay suggest fecal–oral transmission [Loyo et al.,2010].Nevertheless, the role of MCPyV in the oral lesions

of non-MCC individuals and its association with otherviruses in the oral cavity has not yet been addressedin the literature. Therefore, the aim of the study wasto evaluate the presence of MCPyV DNA in salivaand oral tissue biopsies from kidney transplantrecipients and non-transplanted individuals and de-termine its concomitant presence with herpesvirus.

METHODS

Patients

From 2005 to 2007, 60 renal transplant patientswith non-MCC oral lesions (gingivitis and/or peri-odontitis) attended at the University Hospital PedroErnesto, Universidade Estadual do Rio de Janeiro(UERJ) and 75 non-transplanted, non-MCC

�Correspondence to: Rafael Brandao Varella, Laboratory ofVirology, Department of Microbiology and Parasitology, Univer-sidade Federal Fluminense, Rua Ernani Pires de Melo, 101,Niteroi, RJ 24210-130, Brazil. E-mail: rvarella@id.uff.br

Accepted 6 June 2013

DOI 10.1002/jmv.23687Published online 12 July 2013 in Wiley Online Library(wileyonlinelibrary.com).

�C 2013 WILEY PERIODICALS, INC.

individuals, with or without oral lesions, attended atthe Faculty of Dentistry (UERJ) for regular dentalprocedures, were investigated for the presence ofherpesviruses and Merkel cell polyomavirus in salivaand oral tissue biopsies (Table I).

Detection of MCPyV and Herpesvirus in OralSamples

The collected samples were stored in TE bufferwith PBS at �20˚C until the procedure. Sample DNAwas extracted with a Wizard Genomic DNA Purifica-tion Kit (Promega, Madison, WI), according to themanufacturer’s instructions. Nested PCR for the LT3region of the MCPyV genome [Bofill-Mas et al.,2010], the B glycoprotein region of CMV and the U35regions of HHV-6A, HHV-6B, and HHV-7 werecarried out with the conditions described previously[Yalcin et al., 1994; Kidd et al., 2000; Watanabe etal., 2007]. Samples known as positive for MCPyVthrough sequencing were used as positive controls,and ultrapure water was used as negative control ineach run. PCR products were visualized followingelectrophoresis in a 1.5% agarose gel stained withethidium bromide.To determine MCPyV positivity, the first positive

samples for MCPyV were sequenced and confirmed tohave 100% homology through a BLAST query whencompared to other MCPyV sequences available atGenBank. The study was approved by the Committeeon Research Ethics of the University Hospital PedroErnesto (protocol 1138/2005).

Statistical Analyses

Statistical analyses were performed using SAS 6.11(SAS Institute, Cary, NC). The chi-square test orFisher’s exact test was used to examine associationsbetween categorical variables, and the Mann–Whit-ney test was used for non-parametric analyses. Pvalues <0.05 were considered significant.

RESULTS

Due to volume constraints, some samples were nottested for all the viruses under investigation. Al-though gender and age differed between the groups(P ¼ 0.006 and 0.011, respectively, Table I), they didnot influence MCPyV positivity (P ¼ 0.83 andP ¼ 0.49, respectively, Table II).The detection of MCPyV DNA was correlated with

the presence of oral lesions (P ¼ 0.016, Table II).Compared to non-transplanted individuals with orallesions, we also observed that MCPyV DNA waspredominantly detected in the saliva of transplantedpatients (P ¼ 0.009, Table II) but not in tissuebiopsies from these patients (P ¼ 0.18, Table II).Significant associations between MCPyV and CMV

(P ¼ 0.048) and between MCPyV and HHV-6A(P ¼ 0.020) were found in the saliva of transplantedpatients but not in the saliva or tissue biopsies ofnon-transplanted individuals (Table III).

DISCUSSION

MCPyV is the first member of the Polyomaviridaefamily to be linked to malignancy in humans. MCPyVcan be detected in different neoplasic [Mertz et al.,2010] and non-neoplasic tissues, especially skin [Mat-sushita et al., 2013], although its precise site ofreplication and pathogenesis in non-MCC lesions arestill unknown [Foulongne et al., 2010; Husseiny etal., 2010].In the current study, the predominant detection of

MCPyV DNA in the saliva and tissue biopsies ofindividuals with oral lesions, and the similarity inthe frequency of this virus in tissue biopsies fromtransplanted and non-transplanted groups suggestthat MCPyV may play a role in the pathogenesis oforal lesions. Interestingly, any of the herpesvirusesaddressed in this study were significantly correlatedto oral lesions when detected individually or withother herpesvirus (data not shown).

TABLE I. General Characteristics of the Studied Group of Patients and Controls

Variable Category

Txa Non-txb

P-value�n % n %

Genderc Male 34 56.7 24 32.9 0.006Female 26 43.3 49 67.1

Aged Years 42.4 � 13.3 36.6 � 17.0 0.01145 (17 � 68) 34 (13 � 85)

Samplese Oral tissue 53 88.3 38 50.7 0.658Saliva 51 85 42 56

Lesion in oral cavity Pos 60 100 18 24.0 <0.0001Neg 0 0 57 76.0

Statistical significant results (P < 0.05) are in bold.aTransplanted patients.bNon-transplanted individuals.cGender was not available for two non-tx individuals.dAge were expressed by the average � SD and the median (range) and compared by Mann–Whitney test.eOne sample per patient.�x2-test or Fisher exact test.

J. Med. Virol. DOI 10.1002/jmv

Detection of Merkel Cell Polyomavirus in Oral Samples 2017

TABLE II. Variables Associated With MCPyV Detection in Oral Samples Collected From Transplanted and Non-Transplanted Individuals

Variable Sample Category

MCPyV

P-value�Pos (%) Neg (%)

Gender All Male 22 (35.5) 62 (64.5) 0.83Female 18(22.2) 81 (77.8)

Age All �40 23 (37.7) 61 (62.3) 0.21<40 18 (22.8) 79 (77.2)

Transplantation Saliva Txa 18 (36.7) 31 (63.3) 0.009Non–txb 10 (15.4) 55 (84.6)

Tissue biopsy Tx 9 (21.4) 33 (78.6) 0.18Non–tx 3 (10.3) 26 (98.7)

Lesion (Tx and non-tx) Saliva Lesion 21 (33.3) 42 (66.7) 0.016No lesion 7 (13.7) 44 (86.3)

Tissue biopsy Lesion 12 (23.1) 40 (76.9) 0.016No lesion 0 (0.0) 19 (100)

Statistical significant results (P < 0.05) are in bold.aTransplanted patients.bNon-transplanted individuals.�x2-test or Fisher exact test.

TABLE III. Evaluation of MCPyV Co-Detection With Herpesviruses in Oral Samples

Group Sample Co-detection with herpesvirus

MCPyV

P-value�Pos (%) Neg (%)

Txa (N ¼ 60) Saliva CMVcþ 9 (56.3) 9 (27.3) 0.048CMV� 7 (43.8) 24 (72.7)

HHV-6Adþ 5 (83.3) 13 (30.2) 0.020HHV-6A� 1 (16.7) 30 (69.8)HHV-6Beþ 2 (40) 16 (36.4) 0.61HHV-6B� 3 (60) 28 (63.6)HHV-7fþ 1 (25) 17 (37.8) 0.53HHV-7� 3 (75) 28 (62.2)

Tissue biopsy CMVþ 3 (25) 4 (19.1) 0.51CMV� 9 (75) 17 (81)

HHV-6Aþ 2 (50) 5 (17.2) 0.19HHV-6A� 2 (50) 24 (82.8)HHV-6Bþ 2 (33.3) 5 (18.5) 0.38HHV-6B� 4 (66.7) 22 (81.5)HHV-7þ 2 (50) 5 (17.2) 0.19HHV-7� 2 (50) 24 (82.8)

Non-txb (N ¼ 75) Saliva CMVþ 2 (11.8) 4 (23.5) 0.33CMV� 15 (88.2) 13 (76.5)

HHV-6Aþ 0 (0.0) 6 (18.8) 0.67HHV-6A� 2 (100) 26 (81.3)HHV-6Bþ 1 (50) 5 (15.6) 0.33HHV-6B� 1 (50) 27 (84.4)HHV-7þ 2 (50) 4 (13.3) 0.13HHV-7� 2 (50) 26 (86.7)

Tissue biopsy CMVþ 1 (8.3) 2 (20) 0.43CMV� 11(91.7) 8 (80)

HHV-6Aþ 0 (0.0) 3 (14.3) 0.86HHV-6A� 1 (100) 18 (85.7)HHV-6Bþ 0 (0.0) 3 (14.3) 0.86HHV-6B� 1 (100) 18 (85.7)HHV-7þ 3 (13.6) 0 (0.0) —HHV-7� 19 (86.4) 0 (0.0)

Statistical significant results (P < 0.05) are in bold.aTransplanted patients.bNon-transplanted individuals.cCytomegalovirus.dHuman herpesvirus 6A.eHuman herpesvirus 6B.fHuman herpesvirus 7.�x2-test or Fisher exact test.

J. Med. Virol. DOI 10.1002/jmv

2018 Baez et al.

The predominant detection of MCPyV DNA in thesaliva of transplanted patients could be explainedhypothetically by the continuous viral replication inoral lymphoid tissues and salivary glands as aconsequence of immunological impairment, as de-scribed for other viruses [Weikert and Blumberg,2008; Comoli and Ginevri, 2011; Rostaing et al.,2011; Carratala et al., 2012], although this requiresinvestigation for MCPyV infection.Concerning the co-detection of MCPyV and herpes-

virus in transplanted patients (Table III), it isconceivable that these viruses were being shed insaliva as a result of drug-induced immunosuppres-sion rather than mutual stimulation. Thus, the find-ings concerning the association between MCPyV andCMV or HHV-6A in these patients, which weredescribed here first hand, demand further study.The association between CMV and HHV-6 during

reactivation in immunosuppressed patients is alreadyknown. HHV-6 acts as a cofactor for CMV disease intransplant recipients [DesJardin et al., 1998]. HHV-6is also known to stimulate the lytic replication ofKaposi’s sarcoma-associated human herpesvirus[Weikert and Blumberg, 2008]. Polyomavirus onco-proteins LT-Ag and st-Ag can induce cell transforma-tion and disturb cellular gene expression [Feng et al.,2011]. However, data concerning enhanced co-infec-tion between polyomaviruses and herpesvirus arescarce, and the few available reports present conflict-ing results regarding whether these viruses simplyco-exist in certain tissues or exert mutual influence[Goldstein et al., 1984; Kristoffersen et al., 1997;Barzon et al., 2008; Nasiri et al., 2011].This study has some limitations. Due to sample

volume constraints or extinguishment, not all sam-ples were tested for all viruses, including relevantoral agents such as HSV-1 and 2; HPV; EBV, andviral DNA quantification, which was a key element tothe investigation, was not possible as well.However, to our knowledge, this is the first study

to evaluate MCPyV in the oral cavity of renaltransplant patients and its co-detection with herpes-viruses. The results suggest that further studiesshould be performed to investigate the role of MCPyVas an opportunistic agent and the relevance of its co-detection with other viruses in immunocompromisedpatients.

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J. Med. Virol. DOI 10.1002/jmv

Detection of Merkel Cell Polyomavirus in Oral Samples 2019