Polyomaviruses BK and JC DNA infection in peripheral blood cells from blood donors

ABSTRACT Objectives: To investigate the prevalence of human polyomavirus (BK and JC viruses) infection in peripheral blood mononuclear cells of healthy blood donors. Methods: The study included 250 healthy blood donors. Five-milliliter blood was drawn into sterile EDTA tubes and PBMCs were isolated from whole blood. The isolated PBMCs were counted and stored at −70 °C for future investigation. DNA was extracted and subjected to simple, sensitive and specific semi-nested PCR as well as QPCR using both general and specific primers for different assays. Results: Of 250 blood samples, 66 (26.4%) were positive for BKV DNA (146-34,514 copies/106 cells). JC DNA was found in 45 (18%) blood samples (65-21,250 copies/106 cells). Co-infection with these viruses were found in 11 (4.4%) out of 250 blood samples. Discussion: Our study provides important data on polyomavirus infection in peripheral blood mononuclear leukocytes in immunocompetent individuals. These data indicate significant differences between the prevalence of BKV and JCV infection in healthy blood donors. The prevalence of BK and JC virus infection is higher in the age range 30-39 years compared to other age ranges.

BK virus salivary shedding and viremia in renal transplant recipients

Abstract Objectives: This study aimed to verify the presence of polyomavirus BK (BKPyV) in the saliva of kidney transplant recipients and to correlate it with blood viremia. Material and Methods: We have conducted a cross-sectional study with a sample involving 126 renal transplant recipients. 126 samples of saliva and 52 samples of blood were collected from these patients. Detection and quantification of BKPyV were performed using a real-time PCR. To compare the presence of BKPyV in blood and saliva, the binomial proportion test was used. To verify associations between salivary shedding BKPyV and post-transplant periods (in months), the Mann-Whitney test was used. Spearman's correlation was used to correlate the viral load in the saliva with blood of kidney transplant recipients. Results: The mean age of the study group was 51.11±12.45 years old, and 69 participants (54.8%) were female, with a mean post-transplantation time of 4.80±6.04 months. BKPyV was quantified in several samples of saliva and blood, with medians of 1,108 cp/mL and 1,255 cp/mL, respectively. Only 16/52 (30.8%) participants presented BKPyV in blood, and 59/126 (46.8%) excreted the virus in saliva (p=0.004). BKPyV shedding was found in patients at a shorter post-transplantation period (3.86±5.25, p=0.100). A weak correlation was observed between viral quantification in saliva and blood (Spearman's correlation coefficient=0.193). Conclusion: The results of this study suggested that, although saliva excretes more BKPyV than blood, there is no reliable correlation between salivary shedding and blood viremia, showing two independent compartments of viral replication.

Quantitative detection of BK virus in kidney transplant recipients: a prospective validation study / Detecção quantitativa de vírus BK em receptores de transplante renal: um estudo prospectivo de validação

Abstract Introduction: BK virus (BKV) infection in renal transplant patients may cause kidney allograft dysfunction and graft loss. Accurate determination of BKV viral load is critical to prevent BKV-associated nephropathy (BKVAN) but the cut-off that best predicts BKVAN remains controversial. Objective: To evaluate the performance of a commercial and an in-house qPCR test for quantitative detection of BK virus in kidney transplant recipients. Methods: This was a prospective study with kidney transplant recipients from two large university hospitals in Brazil. Patients were screened for BKV infection every 3 months in the first year post-transplant with a commercial and an in-house real time polymerase chain reaction (qPCR) test. BKVAN was confirmed based on histopathology. The area under the curve for plasma qPCR was determined from receiver operating characteristic analysis. Results: A total of 200 patients were enrolled. Fifty-eight percent were male, 19.5% had diabetes mellitus, and 82% had the kidney transplanted from a deceased donor. BKV viremia was detected in 32.5% and BKVAN was diagnosed in 8 patients (4%). BKVAN was associated with viremia of 4.1 log copies/mL, using a commercial kit. The cut-off for the in-house assay was 6.1 log copies/mL. The linearity between the commercial kit and the in-house assay was R2=0.83. Conclusion: Our study shows that marked variability occurs in BKV viral load when different qPCR methodologies are used. The in-house qPCR assay proved clinically useful, a cheaper option in comparison to commercial qPCR kits. There is an urgent need to make BKV standards available to the international community.

Resumo Introdução: A infecção pelo vírus BK (BKV) em pacientes de transplante renal pode levar a disfunção do aloenxerto renal e perda do enxerto. A determinação precisa da carga viral do BKV é fundamental para prevenir a nefropatia associada ao BKV (BKVAN), mas o ponto de corte de melhor valor preditivo para BKVAN ainda é foco de debates. Objetivo: Avaliar o desempenho de um teste de qPCR comercial e outro desenvolvido internamente para detecção quantitativa de vírus BK em receptores de transplante renal. Métodos: O presente estudo prospectivo incluiu receptores de transplante renal de dois grandes hospitais universitários no Brasil. Os pacientes foram testados para infecção por BKV a cada três meses no primeiro ano pós-transplante com um teste comercial de reação em cadeia de polimerase quantitativa em tempo real (qPCR) e outro desenvolvido internamente. A presença de BKVAN foi confirmada com base na histopatologia. A área sob a curva para o qPCR plasmático foi determinada a partir da análise da característica de operação do receptor. Resultados: Um total de 200 pacientes foram incluídos. Cinquenta e oito por cento eram do sexo masculino, 19,5% tinham diabetes mellitus e 82% tiveram seus rins transplantados de doadores falecidos. Viremia de BKV foi detectada em 32,5% dos pacientes e oito (4%) foram diagnosticados com BKVAN. BKVAN foi associada a viremia de 4,1 log cópias/mL usando o kit comercial. O corte para o ensaio interno foi de 6,1 log cópias/mL. A linearidade entre o kit comercial e o ensaio interno foi R2 = 0,83. Conclusão: Nosso estudo demonstrou uma acentuada variabilidade na carga viral de BKV quando diferentes metodologias de qPCR foram utilizadas. O ensaio interno de qPCR mostrou-se clinicamente útil, além de ser uma opção menos onerosa em relação aos kits comerciais de qPCR. Há uma necessidade urgente de se definir padrões de BKV para a comunidade internacional.

Human polyomavirus infection: Cytological and molecular diagnosis / Infecção pelo poliomavírus humano: diagnóstico citológico e molecular

Summary Few studies directly compare urinary cytology with molecular methods for detecting BK and JC polyomaviruses. Reactivation of BKV infection is the main risk factor for the development of nephropathy in immunocompromised individuals. The limitation of the cytological method can be attributed to the stage where the infected cell does not have specific and sufficient morphological characteristics for a conclusive diagnosis and can be easily interpreted as degenerative alteration. Moreover, morphologically, it is not possible to differentiate the two types of viruses. Polymerase chain reaction (PCR), not only is a sensitive method, but also allows differentiation of viral types without quantification, and therefore is not indicative of nephropathy. According to the American Society of Nephrology, real-time PCR would be the gold standard to indicate nephropathy because it allows quantifying the number of viral copies.

Resumo Poucos estudos comparam diretamente a citologia urinária com métodos moleculares para detecção de poliomavírus BK e JC. A reativação da infecção por BKV é o principal fator de risco para o desenvolvimento de nefropatia em indivíduos imunocomprometidos. A limitação do método citológico pode ser atribuída ao estágio em que a célula infectada não possui características morfológicas específicas e suficientes para um diagnóstico conclusivo, podendo ser facilmente interpretada como alteração degenerativa. Além do mais, morfologicamente, não é possível diferenciar os dois tipos virais. A reação em cadeia pela polimerase (PCR), além de ser um método sensível, permite diferenciar os tipos virais sem quantificá-los, não sendo, portanto, indicativa de nefropatia. Segundo a American Society of Nephrology, a PCR em tempo real seria o padrão-ouro para indicar nefropatia, pois permite quantificar o número de cópias virais.

Distribution and genetic diversity of the human polyomaviruses JC and BK in surface water and sewage treatment plant during 2009 in Porto Alegre, Southern Brazil / Distribuição e diversidade genética dos poliomavírus humanos JC e BK em águas superficiais e de estação de tratamento de esgoto durante 2009 em Porto Alegre, sul do Brasil

Abstract The human polyomaviruses JC and BK (JCPyV and BKPyV) are ubiquitous, species-specific viruses that belong to the family Polyomaviridae. These viruses are known to be excreted in human urine, and they are potential indicators of human wastewater contamination. In order to assess the distribution of both JCPyV and BKPyV in urban water samples collected from a sewage treatment plant (STP) and from a canalized water stream of Porto Alegre, Brazil, two nested-PCR assays were optimized and applied to the samples collected. The amplicons obtained were submitted to sequencing, and the sequences were analyzed with sequences of human polyomaviruses previously deposited in GenBank. Twelve out of 30 water samples (40%) were JCPyV positive, whereas six samples (20%) were BKPyV positive. The sequencing results confirmed the presence of JCPyV subtypes 1 and 3, whereas only BKPyV Ia and Ib were found. This study shows for the first time the presence of human polyomaviruses in surface water and in samples collected in a sewage treatment plant in southern Brazil.

Resumo Os poliomavírus humanos JC e BK (JCPyV e BKPyV) são virus ubíquos, espécie-específicos, pertencentes à família Polyomaviridae. Estes vírus são conhecidos por serem excretados pela urina humana, sendo considerados potenciais indicadores de contaminação por águas residuais urbanas. Buscando acessar a distribuição de JCPyV e BKPyV em amostras de águas coletadas de uma estação de tratamento de esgoto e de um arroio canalizado de Porto Alegre, Brasil, duas técnicas de nested-PCR foram otimizadas e aplicadas às amostras coletadas. Os amplificados obtidos foram submetidos ao sequenciamento e suas sequências analisadas com base em sequências de poliomavírus humanos previamente depositadas no GenBank. Doze de 30 amostras de água (40%) foram positivas para JCPyV, enquanto 6 amostras (20%) foram positivas para BKPyV. Os resultados do sequenciamento confirmaram a presença dos subtipos 1 e 3 de JCPyV, enquanto apenas os BKPyV Ia e Ib foram encontrados. Este estudo demonstra pela primeira vez a presença de poliomavírus humanos em águas superficiais e em amostras coletadas em uma estação de tratamento de esgoto na região sul do Brasil.

Detección de polyomavirus BK y JC en extractos leucocitarios de sangre periférica de pacientes con infección por VIH del área norte de Santiago / BK and JC polyomavirus detection in leukocyte extracts of peripheral blood samples of HIV+ patients from the north area of Santiago

Introducción: Polyomavirus BK (BKPyV) y JC (JCPyV) son patógenos persistentes con capacidad de reactivación en inmunocomprometidos, afectando principalmente el sistema urinario y el sistema nervioso central, respectivamente. No existen estudios chilenos en población infectada por VIH. Objetivo: Detectar la presencia de BKPyV y JCPyV en muestras de sangre de pacientes adultos, chilenos, con infección por VIH y correlacionar los resultados con variables clínicas. Materiales y Métodos: Analizamos 96 muestras de extractos leucocitarios de pacientes del área norte de Santiago. El genoma viral se detectó mediante RPC en tiempo real. Para el análisis estadístico se utilizó las pruebas chi-cuadrado de Pearson y Mann-Whitney, considerando significativo un valor de p < 0,05. Resultados: 33% de las muestras resultaron positivas para BKPyV y se encontró una correlación significativa entre la presencia de genoma de BKPyV y la ausencia de carga viral de VIH. Se evidenció la necesidad de considerar más de un blanco de amplificación del genoma de BKPyV. Todas las muestras fueron negativas para JCPyV. Discusión: La prevalencia de BKPyV en pacientes chilenos con infección por VIH es superior a la informada en la mayoría de los reportes internacionales. Se requiere estudios que evalúen la interacción entre ambos virus. Estos pacientes deberían ser sometidos a controles urológicos y nefrológicos periódicos.

Introduction: Polyomavirus BK (BKPyV) and JC (JCPyV) are persistent pathogens able to reactivate in im-munocompromised patients, involving mostly urinary and central nervous system. There are no Chilean studies in HIV positive patients. Objective: To detect BKPyV and JCPyV in blood of Chilean HIV positive adult patients and to correlate these results with clinical-related variables. Materials and Methods: 96 stored blood samples from HIV patients belonging to the north area of Santiago were analyzed. Viral genomes of both viruses were detected by real-time PCR. For statistical analysis, chi-square (Pearson) and Mann-Whitney tests were used and p-values < 0.05 were considered significant. Results: 33% of the samples were positive for BKPyV and a significant correlation was found between the presence of BKPyV genome and the absence of detectable HIV viral load. We demonstrated the need to consider more than one amplification target to detect the BKPyV genome. All the samples were negative for JCPyV genome. Discussion: BKPyV prevalence in Chilean HIV patients is higher than most of international studies. New studies regarding the interaction between both viruses are required. These patients should undergo periodic evaluations by urologist and nephrologist.

JC polyomavirus infection in candidates for kidney transplantation living in the Brazilian Amazon Region

This study evaluated the relative occurrences of BK virus (BKV) and JC virus (JCV) infections in patients with chronic kidney disease (CKD). Urine samples were analysed from CKD patients and from 99 patients without CKD as a control. A total of 100 urine samples were analysed from the experimental (CKD patients) group and 99 from the control group. Following DNA extraction, polymerase chain reaction (PCR) was used to amplify a 173 bp region of the gene encoding the T antigen of the BKV and JCV. JCV and BKV infections were differentiated based on the enzymatic digestion of the amplified products using BamHI endonuclease. The results indicated that none of the patients in either group was infected with the BKV, whereas 11.1% (11/99) of the control group subjects and 4% (4/100) of the kidney patients were infected with the JCV. High levels of urea in the excreted urine, low urinary cellularity, reduced bladder washout and a delay in analysing the samples may have contributed to the low prevalence of infection. The results indicate that there is a need to increase the sensitivity of assays used to detect viruses in patients with CDK, especially given that polyomavirus infections, especially BKV, can lead to a loss of kidney function following transplantation.

High prevalence of the simultaneous excretion of polyomaviruses JC and BK in the urine of HIV-infected patients without neurological symptoms in São Paulo, Brazil / Alta prevalência de excreção simultânea de poliomavírus JC e BK na urina de pacientes HIV+ sem sintomas neurológicos em São Paulo, Brasil

OBJECTIVE: To evaluate the prevalence of the urinary excretion of BKV and JCV in HIV-infected patients without neurological symptoms. METHODS: Urine samples from HIV-infected patients without neurological symptoms were tested for JC virus and BK virus by PCR. Samples were screened for the presence of polyomavirus with sets of primers complementary to the early region of JCV and BKV genome (AgT). The presence of JC virus or BK virus were confirmed by two other PCR assays using sets of primers complementary to the VP1 gene of each virus. Analysis of the data was performed by the Kruskal-Wallis test for numerical data and Pearson or Yates for categorical variables. RESULTS: A total of 75 patients were included in the study. The overall prevalence of polyomavirus DNA urinary shedding was 67/75 (89.3%). Only BKV DNA was detected in 14/75 (18.7%) urine samples, and only JCV DNA was detected in 11/75 (14.7%) samples. Both BKV and JCV DNA were present in 42/75 (56.0%) samples. CONCLUSION: In this study we found high rates of excretion of JCV, BKV, and simultaneous excretion in HIV+ patients. Also these results differ from the others available on the literature.

OBJETIVO: Avaliar a prevalência de excreção urinaria de vírus JC (VJC) e vírus BK (VBK) em pacientes HIV+ sem sintomas neurológicos. MÉTODOS: Amostras de urina de pacientes HIV+ sem sintomas neurológicos foram testados para a presença de VJC e VBK através da técnica de PCR. As amostras foram triadas para a presença de poliomavírus com par de primers complementares a região precoce do genoma do VBK e do VJC (AgT). A presença foi confirmada através de dois outros ensaios de PCR dirigidos a região do gene VP1 de ambos os vírus. A análise estatística foi realizada com auxílio do teste de Kruskal-Wallis para dados numéricos e Pearson ou Yater para variáveis categóricas. RESULTADOS: Ao todo foram inclusos no estudo 75 pacientes. A prevalência geral de excreção de poliomavírus na urina foi de 67/75 (89,3%). O DNA do vírus VBK foi detectado em 14/75 (18,7%) das amostras de urina, e o DNA do VJC foi detectado em 11/75 (14,7%) das amostras testadas. Ambos os vírus estavam presentes simultaneamente em 42/75 (56%) das amostras de urina. CONCLUSÃO: Encontramos, no presente estudo, uma alta taxa de excreção de VJC, VBK e excreção simultânea em pacientes HIV+. Ainda, esses resultados diferem de outros disponíveis na literatura.

Human polyomaviruses JC and BK in the urine of Brazilian children and adolescents vertically infected by HIV

The aim of this study was to characterize the urinary excretion of the BK (BKV) and JC (JCV) human polyomaviruses in a cohort of human immunodeficiency virus (HIV)-infected children and adolescents. One hundred and fifty-six patients were enrolled: Group I included 116 HIV-infected children and adolescents [median age = 11.4 years (y); range 1-22 y]; Group II included 40 non-HIV-infected healthy controls (median age = 11.37 y; range 7-16 y). Single urine samples from both groups were screened for the presence of JCV and BKV DNA by polymerase chain reaction at enrolment. The overall rate of JCV and BKV urinary excretion was found to be 24.4 percent and 40.4 percent, respectively (n = 156). Group I had urinary excretion of JCV and BKV in 27.6 percent and 54.3 percent of subjects, respectively. In contrast, Group II showed positive results for JCV in 17.5 percent of subjects and for BKV in 12.5 percent of subjects (p Pearson JCV = 0.20; p Pearson BKV < 0.0001). In Group I, there was no association between JCV/BKV shedding and age, gender or CD4 values. Patients with an HIV viral load < 50 copies/mL had a lower excretion of BKV (p < 0.001) and a trend of lower JCV excretion (p = 0.07). One patient in Group I (1/116, 0.9 percent) showed clinical and radiological features consistent with progressive multifocal leukoencephalopathy, suggesting that children with HIV/polyomavirus coinfection should be kept under surveillance.

BKV-infection in kidney graft dysfunction

INTRODUCTION: BKV nephropathy (BKN) causes kidney graft loss, whose specific diagnosis is invasive and might be predicted by the early detection of active viral infection. OBJECTIVE: Determine the BKV-infection prevalence in late kidney graft dysfunction by urinary decoy cell (DC) and viral DNA detection in urine (viruria) and blood (viremia; active infection). METHODS: Kidney recipients with >1 month follow-up and creatinine >1.5 mg/dL and/or recent increasing >20 percent (n = 120) had their urine and blood tested for BKV by semi-nested PCR, DC searching, and graft biopsy. PCR-positive patients were classified as 1+, 2+, 3+. DC, viruria and viremia prevalence, sensitivity, specificity, and likelihood ratio (LR) were determined (Table 2x2). Diagnosis efficacy of DC and viruria were compared to viremia. RESULTS: DC prevalence was 25 percent, viruria 61.7 percent, and viremia 42.5 percent. Positive and negative patients in each test had similar clinical, immunossupressive, and histopathological characteristics. There was no case of viremia with chronic allograft nephropathy and, under treatment with sirolimus, patients had a lower viruria prevalence (p = 0.043). Intense viruria was the single predictive test for active infection (3+; LR = 2.8).1,6-4,9 CONCLUSION: DC, BKV-viruria and -viremia are commun findings under late kidney graft dysfunction. Viremia could only be predicted by intense viruria. These results should be considered under the context of BKN confirmation.

Detection and prevalence of polyoma virus BK among Iranian kidney transplant patients by a novel nested-PCR

BK virus is an increasingly recognized pathogen in transplant recipient patients associated with nephropathy and emerged as a cause of allograft failure linked to immunosuppressive regimens in renal transplant recipients. This study develops a sensitive PCR method to detect the viremia and viruria as well as the incidence of BK virus infection in renal transplant recipients. A nested PCR method was developed and a total of 45 paired serum and urine samples from renal transplant recipient patients were collected and tested with the developed assay. The threshold of the developed detection assay was 10 copies/ul of BKV DNA in samples. Our results also indicated that about 40% of the urine and 26.7% of serum samples were positive for BKV in renal transplant patients in this study. This Nested-PCR method was found a specific, sensitive and simple procedure for detection of viruria and viremia of BK virus in renal transplant recipients

Neuropatía por virus BK post trasplante renal diagnostico y seguimiento por PCR en tiempo real / BK virus nephropathy after renal transplantation: Diagnosis and prognosis by real time PCR

La nefropatía producida por el virus BK puede llevar a la pérdida del trasplante renal. El diagnóstico etiológico es importante debido a que la clínica no permite diferenciar entre nefropatía por virus BK y rechazo agudo, en donde los tratamientos de estas dos entidades son diametralmente opuestos. El desarrollo reciente de métodos moleculares muy sensibles y específicos como PCR y PCR en tiempo real para virus BK permiten un diagnóstico de certeza en forma rápida y cuantificar la carga viral presente. El diagnóstico de nefropatía por virus BK se realiza por inmunohistoquímica en una biopsia renal, pero dada la naturaleza multifocal de las lesiones, la sensibilidad no siempre es del 100%. Los nuevos métodos de PCR para detectar virus BK en sangre y orina contribuyen al diagnóstico de nefropatía de una manera más normatizada y menos invasiva. Más aún, la cuantificación del virus BK en sangre por PCR en tiempo real, ha demostrado ser útil en el diagnóstico y monitoreo de esta enfermedad. En este trabajo se presenta el caso de una paciente transplantada renal con nefropatía por virus BK y el desarrollo de un método de PCR en tiempo real para la detección de virus BK en sangre y orina. Esta nueva metodología confirmó el diagnóstico de nefropatía por virus BK lo que permitió un cambio en el esquema de inmunosupresión y la instauración de un tratamiento que pudo ser monitorizado utilizando la carga viral.

BK virus nephropathy may lead to kidney transplant failure. BK infection and acute rejection are clinically undistinguishable, therefore diagnosis of these entities is critical to establish the correct treatment. The new molecular methods using PCR and real time PCR have significantly contributed to the rapid and sensitive diagnosis of BK virus. Furthermore, viral load determination in plasma has significantly been associated with BK virus nephropathy. Definite diagnosis of nephropathy requires renal biopsy, although due to the multifocal nature of the disease sensitivity may be less than 100%. BK detection in blood and urine by PCR has contributed to the diagnosis of nephropathy in a more standardized and less invasive way. Recently, quantification of BK virus in plasma has been used for the diagnosis and monitoring of this disease. In the present study, we describe the validation of a real time PCR method for BK virus detection in plasma and urine and its application for diagnosis and monitoring in a renal transplant patient with nephropathy.

Viral infections of renal allografts--an immunohistochemical and ultrastructural study.

Viral infections have been recognized as an integral part of both graft injury and rejection. On routine histology, viral infections are diagnosed only when fully established, by the presence of viral inclusions or cytopathic effect. Although renal transplants are routinely done in many centres in India, the incidence of viral infections is largely unkown. This study was aimed at detecting 5 viral infections namely, cytomegalovirus (CMV), BK polyoma Virus (BKV), Herpes Simplex Virus1 and 2 (HSV1 and 2) and Epstein Barr Virus (EBV) in renal biopsies from 321 renal allograft patients, using immunohistochemical and electron microscopic studies. Sixty two biopsies were selected from a total of 414 (belonging to 321 patients) for immunostaining on the basis of features suspicious of viral infections in hematoxylin and eosin stained sections. Immunostaining confirmed CMV infection in 8 biopsies, BKV infection in 31 biopsies and HSV1 in only 2 biopsies. HSV2 and EBV were not detected in any biopsy. Two biopsies showing CMV immunopositivity and 5 of BKV were further processed for electron microscopy, which supported the diagnoses. Thus, the study highlights the prevalence of BKV and CMV infections in renal transplant patients having graft dysfunction, to be 9.3% and 1.9%, respectively. Besides, only one case each was diagnosed as CMV infection and BKV infection in routine histopathological reporting, establishing the importance of immunohistochemical studies in early diagnosis of these viral infections.

Diagnóstico citológico y ultraestructural de infección por virus polioma humano (BK) en el sedimento urinário / Cytological and ultrastructural diagnosis of human polyoma virus infection (BK) in the urinary sediment

En 1971 se aislaron dos virus Polioma humanos: JC causante de la leucoencefalopatía multifocal progresiva y BK que están asociados a estenosis ureteral en algunos pacientes trasplantados renales. Los enfermos que hacen reactivación de la infección excretan el virus por la orina y descaman células uroteliales con típicas inclusiones diagnósticas. En caso de duda sobre el virus responsable de estas inclusiones, puede recurrirse a la ME o a estudios serológicos. Otro diagnóstico diferencial es con el cáncer urotelial. La reactivación ocurre en inmunodeficientes y también en pacientes con afecciones clínicas sin obvia deficiencia inmunológica. La citología puede utilizarse para pesquisa catastral. Se presenta un caso de infección por virus Polioma humano (*BK) diagnosticado por la citología urinaria y confirmado por ME, con el objeto de hacer conocer esta patología en nuestro medio y su posible confusión con cáncer urotelial en el citodiagnóstico