Infección por Poliomavirus en pacientes trasplantados renales del Hospital Carlos Andrade Marín, enero 2013 a diciembre 2014 / Polyomavirus infection in kidney transplant patients of the Carlos Andrade Marin Hospital from January 2013 to December 2014

Introducción: La nefropatía del poliomavirus tipo BK, o nefropatía por VBK, se asocia a disfunción del injerto renal teniendo como factor de riesgo del donante, la presencia de virus VBK activo, infección por Citomegalovirus. La presencia de células de Decoy en orina y de virus BK en el plasma son los marcadores de la replicación del virus del polioma. Materiales y métodos: Estudio retrospectivo observacional en pacientes sometidos a trasplante renal en el período: enero 2013 a diciembre 2014. Los métodos empleados para establecer el diagnóstico incluyeron la determinación de las características clínicas; el hallazgo de células de Decoy en orina; reacción en cadena de polimerasa (PCR) en sangre para detectar el virus BK; inmunohistoquímica en biopsia renal. Resultados: De 53 pacientes con trasplante renal, cinco desarrollaron nefropatía inducida por virus del polioma humano. De ellos, cuatro tuvieron donante cadavérico y uno, donante vivo relacionado. El deterioro de la función renal se estableció 3 a 7 meses postrasplante, en pacientes que recibieron terapia inmunosupresora a base de micofenolato de mofetilo o tacrolimus. De los cinco pacientes en uno se evidenció células de Decoy en orina positivo y todos tenían carga viral plasmática positiva. Discusión: La nefropatía por Virus BK en pacientes trasplantados renales constituye una infección secundaria relacionada con el rechazo, el diagnóstico se establece con el análisis de marcadores específicos.

Introduction: Polyomavirus type BK (BKV) nephropathy is associated with renal transplant dysfunction, since donos carrying the VBK hold a risk factor of the concurrent cytomegalovirus infection. The presence of Decoy cells in urine and the VBK in plasma are the markers of polioma virus replication. Methods: Retrospective observational study focused on patients who received renal transplants in the period between January 2013 to December 2014. In order to make the diagnosis more accurate, we tested for clinical characteristics; the presence of Decoy cells in urine; polymerase chain reaction (PCR) blood test to detect the BK virus and immune histochemical test on renal biopsies. Results: Of 53 renal transplant patients, five developed nephropathy induced by human polyoma virus. Four received transplants from cadaveric donors and one from a living donor. Renal function deterioration was seen between three to seven months after the renal transplant in those patients receiving immunosuppression with mycophenolate mofetil or tacrolimus. Of the five patients, one tested positive for decoy cells in urine, and they all tested positive for plasmatic viral load. Discusion: The presence of BKV nephropathy in renal transplant patients is a secondary infection that might cause organ rejection. The diagnosis is made with specific biomarkers.

Decoy cells in the urine cytology of a renal transplant recipient: An immunohistochemical study.

Human polyoma virus causes renal dysfunction and graft loss as a result of tubulo-interstial nephritis in renal transplant recipients after reactivation of latent virus in renal epithelium. The infected cells in the urinary sediments are characterized by large homogenous inclusions, which may cause diagnostic error in urine cytology. The epithelial cells with polyoma viral inclusions in urine cytology specimens are termed Decoy cells to caution pathologists not to misdiagnose these cells as cancer cells. We present a case of polyoma viral changes detected the first time in our laboratory in the urine of a 46year old male who underwent renal transplantation six months back and followed by immunotherapy. Urine cytological examination showed decoy cells and subsequently revealed on histopathology. Immunoperoxidase staining for SV-40 LT antigen (LT ag), expression of proliferating cell nuclear antigen (PCNA), p53 and Rb genes were also studied in the tissue sections for further observation. The expression of SV40 LT ag was negative, while PCNA showed strong positivity; p53 and Rb were expressed moderately in the nuclei of cells in the tubules. The report of a case of decoy cells in the urine of a patient with renal transplantation focuses the importance of cytologic analysis of urine as a diagnostic tool for screening renal transplant recipients at risk of polyoma viral infection.

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.

Comparison of Detecting Methods of BK Virus Infection in Patients with Renal Allograft Recipients

BACKGROUND: BK virus nephropathy (BKVN) is an emerging problem as a consequence of the use of potent immunosuppressive agents. Because optimal detection methods for the diagnosis of BKVN are required clinically, we compared the results of renal allograft biopsy, urine cytology, and urine and blood viral loads. METHODS: Four hundred sixty two case notes from 2004 to 2009 at Seoul St. Mary's Hospital were reviewed. During that period, 286 cases of urine cytology for decoy cells, 938 cases of urine BKV reverse transcription-polymerase chain reaction (RT-PCR), and 1,029 cases of blood BKV RT-PCR were performed. All diagnostic methods were performed in 85 cases. RESULTS: A histological diagnosis of BKVN was made in 2.4% of cases (11/462). Urine cytology for decoy cells was positive in 26.2% (75/286). BKV RT-PCR revealed viruria in positivity of 22.1% (207/938) and viremia in 5.2% (54/1,029). In cases of BKVN, the sensitivities of urine and blood BKV RT-PCR were all 100% and the specificities were 69% and 94.5%, respectively. In cases with positive urine decoy cells, the sensitivities of urine and blood BKV RT-PCR were 50% and 27.7%, with specificities of 77.7% and 100%, respectively. CONCLUSIONS: BKV screening by RT-PCR assays may be a clinically useful noninvasive test to identify renal recipients with concurrent BKVN.

Characteristics of BK virus infection in renal transplant recipients / 中华肾脏病杂志

Objective To investigate the characteristics of BK virus (BKV) infection in renal transplant recipients. Methods A total of 243 renal recipients from our clinic within 48 months after transplantation were enrolled as the trial group and 82 healthy people as the control group. Urine and peripheral blood samples of these two groups were harvested for urinary sediment BKV cytology by Decoy cell counting and BKV DNA by real-time PCR. Results The positive rates of urinary Decoy cell, BKV viruria and viremia were 35.4%, 36.6% and 16.9% in trial group, and 4.9%, 20.7% and 2.9% in control group, respectively. In trial group, the medians of urinary Decoy cell, urinary BKV and peripheral blood BKV were 6/10 HPF, 1.00×104 copy/ml and 6.87×103 copy/ml respectively, while in control group, they were 2/10 HPF, 1.10×104 copy/ml and 2.24×1(3 copy/ml. Compared with the healthy people, the positive rates and the levels of BKV DNA in urine and peripheral blood of recipients were significantly higher. The amount of urinary Decoy cells was positively correlated to urinary BKV load (r=0.636, P＜0.01). Conclusions BKV replication is easier to happen in renal recipients as compared to healthy people. Counting of urinary Decoy cells is convenient, useful and sensitive to evaluate BK viruria and viremia in renaltransplant recipients. BKV DNA detection in urine and peripheral blood can be used to screen the evidence of BK reaction in order to prevent irreversible graft damage by BKV.[ Key words ] Kidney transplantation; BK virus; Kidney diseases; Decoy cells