Elsevier

Transplantation Proceedings

Volume 37, Issue 9, November 2005, Pages 3770-3773
Transplantation Proceedings

Complication
Infection
Polymerase Chain Reaction Detection of BK Virus and Monitoring of BK Nephropathy in Renal Transplant Recipients at the University Hospital La Fe

https://doi.org/10.1016/j.transproceed.2005.09.194Get rights and content

Abstract

Introduction

Reactivation of BK infection occurs in immunocompromised hosts causing tubulointerstitial nephropathy (BKVN). Approximately 5% of kidney transplant recipients (KTR) develop BKVN, special half of whom lose their grafts. However, BKVN morphologic diagnosis on a renal biopsy is complicated, because the cytopathic changes can sometimes mimic rejection. Thus, BKV DNA–polymerase chain reaction (PCR) assay on serum, urine, and renal tissue is useful for early detection and monitoring of BKV.

Materials and methods

We performed routine monthly urine cytologies looking for decoy cells as a marker of virus replication. Then, we performed a qualitative PCR on urine and serum in all recipients (independently of positive or negative cytology). We amplified 3 BK viral genome regions, LT (early transcription region) and VP1 (late transcription region) seeking a more accurate virus detection, and the TCR (control transcription region) region to perform a polymorphism sequence analysis to identify the BK genomic variant. Finally, the BKVN diagnosis was confirmed using renal biopsy.

Results

At present, 132 patients have been monitored. Thirteen of 40 (33%) were PCR-urine–positive cases (5 LT+/VP1− and 8 LT+/VP1+), and 10 of 132 (7.5%) were PCR-serum–positive cases (7 LT+/VP1− and 3 LT+/VP1+). When we compared PCR-urine and cytology results, 11 of 40 (27.5%) patients showed a positive cytology, 6 of whom were PCR- urine–positive (1 LT+/VP1− and 5 LT+/VP1+); whereas, 29 patients showed a negative cytology, 7 of whom were PCR-urine–positive(3 LT+/VP1− and 4 LT+/VP1+). Thus, comparison of PCR- urine and cytology results revealed false-positive and false-negative cases. Finally, TCR sequence analysis was performed in 9 patients to identify the BK genomic variants.

Conclusion

Testing for BKV DNA in urine and serum is a noninvasive early detection assay and monitoring tool.

Section snippets

Subjects

Management of BK infection was based on the Nickeleit scheme.10 Samples were collected during the first posttransplantation year from 121 adult patients (75 males and 46 females; mean age, 48 years) and 11 pediatric patients (7 boys and 4 girls; mean age, 12 years).

First, we performed a monthly urinary cytology, namely between 1 and 11 cytologies with a mean of 5 per patient, looking for decoy or comet cells as a possible marker of viral replication. A urine aliquot was also frozen at −20°C.

Results

In this study, 132 consecutive kidney transplant recipients were monitored over 18 months using monthly urinary cytology, among which 23 (17.4%) showed at least 1 decoy cell in the urinary sample. The molecular study (PCR) revealed that 10 of 132 (7.5%) patients were PCR-serum–positive (7LT+/VP1− and 3 LT+/VP1+), and 13 of 40 (33%) were PCR-urine–positive (5LT+/VP1− and 8 LT+/VP1+). We confirmed the BKVN diagnosis using PCR on the renal biopsy specimen in 3 of 12 cases in which a biospsy was

Discussion

In the present study, BK-PCR assay for early detection of BK viral infection was performed on 132 recipients during the first posttransplantation year. In contrast to other previous BK-PCR assays,9, 10 we amplified 2 different BK genome regions (LT and VP1), seeking a more accurate BKV detection to avoid false-negative results due to viral genomic mutations, which prevent the primers from exactly matching with the complementary viral DNA, thus inhibiting the amplification of the BK target

References (19)

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Cited by (19)

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    Thus, urine cytology with quantitative counts can reflect not only BK viral load in vivo, but also renal histologic presentation indirectly. Furthermore, electron microscopy was used in this study to observe viral particles in the nucleus of sloughed tubular cells in order to confirm the presence of decoy cells because marked nuclear enlargement due to reactive and regenerative changes may closely resemble the PV cytopathic effect mentioned in the context of the research of Vera-Sempere et al. (2005). Also, electron microscopy studies may be useful for diagnosis and confirmation of PV infection based on the different ultrastructural morphology of the most common viral infections: adenovirus, herpesvirus, and CMV inclusions (Drachenberg et al., 2005).

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    The nonalteration of immunosuppression when the first BKV DNAemia occurred might explain why the prevalence of BKVAN was 3.8% in our cohort. However, these figures are similar to others found in the literature.6–13 The highest prevalence of BKV replication occurs between 2 to 6 months posttransplantation.4,11,14

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    Our management of BK infection is based on the Nickeleit scheme.10

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Supported by FIS grant #C03/03 of the Organización Nacional de Transplantes (ONT) of Spain.

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