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

Correlation between the presence of degenerated inclusion-bearing cells in voided urine samples and the occurrence of polyomavirus infection

OBJECTIVE

The purpose of the present, prospective, cohort study was to monitor urine cytology samples from recipients of renal transplants to search for the occurrence of decoy cells and degenerated inclusion-bearing cells with an aim to correlate the existence of these cells with molecular detection of polyomavirus BK (BKV) DNA in urine.

MATERIAL AND METHODS

This study included patients who underwent renal transplantation. Patients had their urine tested quarterly, during the first year post-transplantation, for the presence of decoy cells and degenerated cells, as well as by quantitative determination of BKV load in the urine and plasma.

RESULTS

Three hundred and sixty-one examinations were performed on 101 patients within 12 months of attendance. Urine cytology results were: 198 (54.9%) negative and 60 (16.6%) positive for the presence of viral cytopathic effects depending on the presence of BKV infection, 72 (19.9%) positive for the manifestation of degenerated cells and 31 (8.6%) unsatisfactory for analysis. There was a subtle tendency towards the presence of degenerated inclusion-bearing cells in cases in which the virus was detected in voided urine. However, the presence of degenerated cells exhibited a tendency to BKV positivity in months 3, 6 and 9 and, exclusively in month 12, this trend was statistically significant.

CONCLUSIONS

There were not enough strong morphological and staining elements to state the origin of the degenerated cells or to describe the nature of the infection (viral or bacterial), given that these cells were undergoing an apoptotic process in post renal transplant patients.

Prospective controlled protocol for three months steroid withdrawal with tacrolimus, basiliximab, and mycophenolate mofetil in renal transplant recipients

During the past few years, new immunosuppressants, such as tacrolimus, mycophenolate mofetil (MMF) and basiliximab, have been shown to successfully decrease the incidence of acute rejection, possibly acting as potent substrates for safe steroid withdrawal. Therefore, clinical outcome of 3 months steroid withdrawal, while using the above immunosuppressants, was analyzed. Clinical trial registry No. was NCT 01550445. Thirty de novo renal transplant recipients were enrolled, and prednisolone was slowly withdrawn 3 months post-transplantation by 2.5 mg at every two weeks, until 8 weeks. During steroid withdrawal, 10 patients (30.0%) discontinued the protocol and they were maintained on steroid treatment. Among 20 steroid free patients, 8 patients (40.0%) re-started the steroid within 12 months post-transplantation. By the study endpoint, 12 (40%) recipients did not take steroid and survival of patients and grafts was 100%. In conclusion, in kidney transplant patients, 3 months steroid withdrawal while taking tacrolimus, basiliximab and mycophenolate mofetil was not associated with increased mortality or graft loss. Despite various causes of failure of steroid withdrawal during the follow-up period, it is a strategy well advised for kidney transplant recipients with regard to long-term steroid-related complications.

Different patterns of BK and JC polyomavirus reactivation following renal transplantation

AIM

Reactivation of latent BK polyomavirus (BKV) infection is relatively common following renal transplantation and BKV-associated nephropathy has emerged as a significant complication. JC polyomavirus (JCV) reactivation is less well studied. The aim of the study was to determine reactivation patterns for these polyomaviruses in renal transplant recipients using an in-house quantitative real-time multiplex PCR assay and IgG serological assays using recombinant BK and JC virus-like particles.

METHODS

Retrospective analysis of urine and plasma samples collected from 30 renal transplant patients from February 2004 to May 2005 at Leeds Teaching Hospitals NHS Trust. Samples were collected at 5 days and thereafter at 1, 3, 6 and 12 months post-transplantation.

RESULTS

Eight patients (26.7%) were positive for BK viruria; three of these patients submitted plasma samples and two had BK viraemia. Five patients (16.7%) were positive for JC viruria. A corresponding rise in BKV and JCV antibody titres was seen in association with high levels of viruria.

CONCLUSIONS

Different patterns of reactivation were observed: BK viruria was detected after 3-6 months, and JC viruria was observed as early as 5 days post-transplantation. One patient had biopsy-proven BKV nephropathy. No dual infections were seen. In order to ensure better graft survival, early diagnosis of these polyomaviruses is desirable.

Renal allograft recipient with co-existing BK virus nephropathy and pulmonary histoplasmosis: report of a case

Renal allograft recipients are prone to opportunistic infections, rarely multiple coexisting infections, due to the immunocompromised state. To the best of our knowledge, no case of a co-existing polyoma virus nephropathy and pulmonary histoplasmosis in a renal allograft recipient has been reported so far in the available literature. A 55-year-old male renal allograft recipient underwent graft biopsy for asymptomatic graft dysfunction. The graft biopsy showed features of polyoma virus nephropathy. Soon after, he developed fever with pulmonary nodules. Fine-needle aspiration from lung nodules showed intracellular yeast forms of histoplasma. The patient responded well to amphotericin B with subsidence of fever. The co-existence of renal allograft-limited infection like polyoma virus and systemic fungal infection such as histoplasmosis should be kept in mind in a transplant recipient with graft dysfunction and non-specific systemic symptoms. Prompt recognition of these infections permits the clinician to institute appropriate therapeutic modification and improved survival.

Viral lower urinary tract infections

Lower urinary tract infections (UTIs) are common among the general population and are most often caused by bacterial pathogens. Viruses are an uncommon cause of UTIs in an immunocompetent host; however, viruses are increasingly recognized as the cause of lower UTI, especially hemorrhagic cystitis, among immunocompromised patients. BK virus, adenovirus, and cytomegalovirus are predominant pathogens involved in hemorrhagic cystitis after stem cell and solid organ transplantation, and their early diagnosis and treatment may prevent significant morbidity of hemorrhagic cystitis. The diagnosis of viral lower UTI is based on molecular techniques, and real-time polymerase chain reaction is often the method of choice because it allows for quantification of viral load. Cidofovir is becoming a drug of choice in viral UTIs because it is active against the most common viral pathogens. This review discusses the epidemiology, pitfalls in diagnosis, and current treatment of viral UTIs.

Prospective evaluation of BK virus DNAemia in renal transplant patients and their transplant outcome

BACKGROUND

After renal transplantation, the prevalence of BK virus (BKV) viruria, viremia, and nephritis (BKVAN) has been estimated at 30%, 13%, and 8%, respectively.

PATIENTS AND METHODS

The aim of this prospective study was to assess the occurrence of BKV DNAemia during the first year after renal transplantation and to determine the prevalence of BKVAN, in the absence of immunosuppression alteration, following positive BKV DNA. BKV DNAemia was assessed systematically in 104 renal transplant patients on postoperative days 60, 90, 135, 180, 270, and 360.

RESULTS

Of the 104 patients, 7 (6.7%) presented with at least 1 episode of BKV DNAemia. Those with positive BKV DNAemia had a cumulative steroid dose administered from days 0 to 7 which was higher than those without BKV DNAemia (2.13 +/- 0.6 vs 1.6 +/- 0.4; P = .024). The first BKV DNAemia occurred at 170 (30-460) days posttransplantation. Of the 7 patients who experienced at least 1 BKV DNAemia, 3 had 1 occurrence, but the other 4 had repeated occurrences. These 4 patients developed overt BKVAN at 1 (2 cases) to 2 weeks (2 cases) after the first occurrence of BKV DNAemia. These 4 patients were withdrawn from mycophenolate mofetil, which was in all cases replaced by leflunomide. With a follow-up ranging from 14 to 24 months after the first episode of BKV DNAemia, patient and graft survivals were both 100%. Current serum creatinine ranges from 97 to 173 micro mol/L for those who had only 1 episode of BKV DNAemia, and from 144 to 240 micro mol/L for those who had overt BKVAN.

CONCLUSION

Although BKV DNAemia is a rare event after renal transplantation, it is often associated with BKVAN, which may be treated successfully by the alleviation of immunosuppression and leflunomide therapies.

Viral lower urinary tract infections

Lower urinary tract infections (UTIs) are common among the general population and are most often caused by bacterial pathogens. Viruses are an uncommon cause of UTIs in an immunocompetent host; however, viruses are increasingly recognized as the cause of lower UTI, especially hemorrhagic cystitis, among immunocompromised patients. BK virus, adenovirus, and cytomegalovirus are predominant pathogens involved in hemorrhagic cystitis after stem cell and solid organ transplantation, and their early diagnosis and treatment may prevent significant morbidity of hemorrhagic cystitis. The diagnosis of viral lower UTI is based on molecular techniques, and real-time polymerase chain reaction is often the method of choice because it allows for quantification of viral load. Cidofovir is becoming a drug of choice in viral UTIs because it is active against the most common viral pathogens. This review discusses the epidemiology, pitfalls in diagnosis, and current treatment of viral UTIs.

Primer: histopathology of polyomavirus-associated nephropathy in renal allografts

The BK polyomavirus exhibits tropism for the renal tubular epithelium, where it establishes latent infection. Vigorous immunosuppression of renal allograft recipients can lead to reactivation of the infection and the development of polyomavirus-associated nephropathy (PVAN). Clinically, gradually decreasing renal function, viremia and viruria are observed several months after transplantation; allograft failure occurs in 1-10% of patients. Definitive diagnosis requires an allograft biopsy. Histologically, viral replication results in tubular epithelial cell enlargement, karyomegaly and nuclear inclusion bodies. The cytopathic changes are often associated with lysis of tubular epithelial cells, denudation of the basement membrane and an interstitial inflammatory response. The involvement is multifocal; distal nephron segments are more severely affected than proximal segments. Changes observed during light microscopy are suggestive but not pathognomonic for PVAN, and the diagnosis must be confirmed by adjunct studies. Adjunct studies consist of immunohistochemistry on paraffin sections using an antibody to the SV40 large T antigen, or electron microscopy of infected tubular epithelial cells (virions 40 nm in diameter). PVAN manifests in three histologic patterns: pattern A, viral cytopathic changes with no or only minimal inflammation; pattern B, cytopathic and cytolytic lesions with interstitial inflammation; or pattern C, predominantly interstitial fibrosis and tubular atrophy, with variable cytopathic and inflammatory changes. These patterns correlate with clinical outcomes.

Renal Donor Implication in the Origin of BK Infection: Analysis of Genomic Viral Subtypes

BK virus (BKV) reactivation in immunocompromised kidney transplant patients can produce a tubulointerstitial nephropathy (BKVN). Molecular tools that test for DNA-BKV provide early detection and assist in management, but some aspects of the pathogenesis of this infection, such as donor causality, remain unclear.

MATERIALS AND METHODS

Between November 2004 and January 2006, 55 Spanish kidney donors were studied for BK infection. A quantitative PCR assay was performed on urine and serum to detect BKV. To determine the origin of the viral infection, a transcription control region of the BK polymorphism sequence was designed to identify the viral subtype.

RESULTS

Fifteen of 55 (27%) donors were BK-PCR positive: 13 in urine and 2 in serum and urine. Moreover, monitoring of recipient pairs detected BK-PCR positivity in 14 of 73 recipients. We studied eight BK-PCR positive recipients (corresponding to four pairs) and their respective donors. The same viral genome was observed in the four pairs, namely, the A250-1-a, WW-like, AS, and JL genotypes. Interestingly, one of the four pairs showed the donor and the two recipients to display exactly the same JL genotype.

CONCLUSION

On the basis of our preliminary results analyzing the molecular fingerprints of donor and recipient pairs, we have presented new data implicating the donor, in at least some cases, as the source of BK infection.