BK polyoma virus nephropathy among Iranian renal transplant recipients

Routine immunohistochemistry study for polyomavirus BK nephropathy in transplanted kidney biopsies, is it recommended?

BACKGROUND

Early diagnosis and treatment of Polyomavirus BK Nephropathy (PVBKN) is a challenging issue in the management of patients with kidney transplantation. Currently, histopathologic diagnosis is the gold standard method for diagnosis of PVBKN. However, typical viral inclusions may not be found in early stages of the PVBKN and should, instead, be diagnosed using immunohistochemistry (IHC) study. There is no clear consensus about routine IHC tests in the pathologic evaluation of transplanted kidney biopsy samples.

MATERIAL AND METHODS

The current study was conducted on transplanted kidney biopsy samples, since 2016 to 2019. The patients who have presented with new onset of allograft dysfunction, at least 2 weeks after transplantation surgery, were included in our study. All these biopsy samples were evaluated with routine renal biopsy stains as well as IHC for SV40 (Simvian Virus 40) antigen. The identification of typical nuclear virus inclusion body and any nuclear positive staining on IHC (≥1+ positive result) were considered as definite evidence of PVBKN. Sensitivity, specificity, Positive Predictive and Negative Predictive Values (PPV and NPV) of histopathologic assessment without IHC study were evaluated.

RESULTS

Among 275 included cases, 18 (6.5%) patients with PVBKN were diagnosed. In patients with PVBKN, typical viral inclusions were detected in 14 samples (77.7%), on primary histopathological examination. However, virus-infected cells were identified just after IHC study in 4 (22.2%) of patients. Sensitivity, Specifity, PPV and NPV of morphologic histopathological assay without IHC for detection of PVBKN was 77.7, 100, 100 and 98.4% respectively.

CONCLUSION

Routine IHC study for SV40 in all transplanted kidney biopsy samples with new onset of allograft dysfunction, will enhance the diagnostic sensitivity of early stage disease detection.

Druggability of cavity pockets within SARS-CoV-2 spike glycoprotein and pharmacophore-based drug discovery

Aim: Virus spike glycoprotein of SARS-CoV-2 is a good target for drug discovery. Objective: To examine the potential for druggability of spike protein for pharmacophore-based drug discovery and to investigate the binding affinity of natural products with SARS-CoV-2 spike protein. Methods: Druggable cavities were searched though CavityPlus. A pharmacophore was built and used for hit identification. Autodock Vina was used to evaluate the hits' affinities. 10 chemical derivatives were also made from the chemical backbone to optimize the lead compound. Results: 10 druggable cavities were found within the glycoprotein spike. Only one cavity with the highest score at the binding site was selected for pharmacophore extraction. Hit identification resulted in the identification of 410 hits. Discussion: This study provides a druggable region within viral glycoprotein and a candidate compound to block viral entry.

Polyomavirus Associated Nephropathy: Frequency and Graft Survival Analysis in Northeast of Iran

Background & Objective:

Polyomavirus-associated nephropathy (PVAN), mainly caused by the BK virus, is one of the most important infectious complications of kidney transplantation. The leading histopathologic characteristics of PVAN is viral cytopathic effects, such as nucleomegaly with smudged or clumped chromatin and intranuclear ground-glass inclusion, mostly in tubular epithelial cells. Moreover, tubular necrosis, tubulitis, interstitial inflammation, atrophy, and fibrosis have been noted. Positive immunohistochemistry (IHC) staining for SV-40 highlights the infected epithelial cells of renal tubules.

Methods:

A total of 85 core needle biopsies of transplanted kidneys were evaluated histologically and were stained for SV-40 using the IHC method. In addition, a follow-up of graft failure was performed.

Results:

Our findings revealed that the frequency of polyomavirus infection in kidney transplant patients in the Northeast of Iran is 4.7%. There was no significant correlation between PVAN and graft rejection. Although a higher rate of graft loss was observed in PVAN patients, in comparison with non-PVAN patients (25% vs. 14.8%), the difference was not statistically significant. Moreover, patients with immunohistochemically confirmed PVAN and those with histopathologic features of viral-like cytopathic effects had significantly lower graft survival in the follow-up period (42.5 vs. 196.8 months and 109.4 vs. 205.7 months, respectively).

Conclusion:

The frequency of polyomavirus infection in kidney transplant patients in the Northeast of Iran is 4.7%. There was no significant correlation between PVAN and graft rejection. Furthermore, we observed that polyomavirus infection accelerates the course of graft loss.

Viruria of Human BK Virus and John Cunningham Virus among Renal Transplant Recipients and Healthy Control in Southeast of Caspian Sea

BACKGROUND

Members of the Polyomaviridae family, BK virus (BKV), and John Cunningham virus (JCV) are linked to polyomavirus-associated nephropathy-associated transplant rejection in immunodeficient patients.

OBJECTIVE

The aim of the study was to evaluate the prevalence of BKV and JCV in immunocompetent individuals in the north of Iran.

METHODS

Ninety-one urine samples were obtained from renal transplant recipients with a mean age of 39.78 ± 11.19 years. A healthy control group of 65 volunteers with an average age of 40.32 ± 10.7 years also contributed. After DNA extraction, positive cases were detected through PCR. Genotyping was done by alignment and phylogenetic tree construction of the VP1 region against all known JCV and BKV genotypes.

RESULTS

The prevalence of BKV and JCV was 15.38 and 19.78%, respectively. JCV was detected in 7.69% of the control group. The prevalence of the BKV between the case and control groups was significant (p < 0.0001). There was no significant association between BKV and JCV and duration of dialysis (p > 0.05). Overall, 62.16% of JCV cases were genotype I. Besides, genotype II was dominant within patients with BKV-positive patients.

DISCUSSION

The results obtained here show a relatively lower prevalence of BKV and JCV in immunocompromised renal transplant receivers and healthy control than those reported from other areas in Iran. JCV genotyping was evaluated for the first time in Iran. Genotype I for JCV and genotype II for BKV were dominant genotypes in the north of Iran.

Survey of BK Virus in Renal Transplant Recipients in Iran: A Systematic Review and Meta-Analysis

INTRODUCTION

BK virus (BKV) infection in renal transplant (RT) recipients can cause hemorrhagic cystitis, transient renal dysfunction, and BKV nephropathy (BKVN). The prevalence and significance of BKV in RT recipients remain to be clarified in the Iranian population. The purpose of this review is to summarize the overall prevalence of BKV infection in RT recipients from previously published studies in Iran.

METHODS

We systematically reviewed articles through a comprehensive search of the main electronic and Persian national databases up to November 2019.

RESULTS

The overall pooled prevalence of BKV infection among the Iranian population was 23% (95% CI; 15-33%). Comparing these studies revealed that the prevalence of BKV in plasma samples ranges from 3 to 40%, in renal biopsies 1-13%, and in urine samples 10-49%. Due to substantial heterogeneity among reported studies (I2 = 93%, p < 0.01), random-effect meta-analysis was performed. BKV infection rate was slightly higher in women than men (16%, p = 0.04 vs. 14%, p < 0.01, respectively). The majority of the studies employed real-time PCR (24%, I2 = 93, p < 0.01) and analyzed plasma samples alone or in combination with other types of specimens. BKV prevalence from 5 cities among the Iranian population showed a higher prevalence rate in Guilan.

CONCLUSION

Our analysis provides a preliminary estimate of the epidemiology of BKV infection in RT recipients in Iran. These results arouse a need for more epidemiological studies of BKV infection in different unanalyzed regions in Iran. Early detection of BKV in RT recipients helps timely nephropathy diagnosis and prevents graft loss.

Clinical characteristics and outcomes of late-onset BK virus nephropathy in kidney and kidney-pancreas transplant recipients

BACKGROUND

BK virus nephropathy (BKPyVAN) is a major complication in kidney transplant recipients (KTR) and typically occurs within 1 year of transplant. Guidelines vary in recommendations for BKPyV screening beyond 1 year. A systematic characterization of risk factors and outcomes of late-onset (>1 year) BKPyVAN has not previously been reported.

METHODS

We retrospectively compared characteristics and outcomes of early- (<1 year) and late-onset BKPyVAN (definitive [biopsy-confirmed] or presumptive [plasma BKPyV >10 000 copies/mL]) in a cohort of 671 KTR and simultaneous kidney-pancreas transplant (SPK) recipients between 2008 and 2013 at a single US transplant center. Proportions were compared using Chi-square or Fisher's exact test with P < .05 considered significant.

RESULTS

BKPyVAN was diagnosed in 96 (14.3%) patients (proven 16.7%, presumptive 83.3%): 79 (82.3%) early- and 17 (17.7%) late-onset. The proportion with late-onset BKPyVAN was significantly higher among SPK than KTR (4 of 7 [57.1%] vs 13 of 89 [14.6%], P = .017). Late-onset represented "de novo" infection (no BKPyV detection within the first year) in 14 (82.4%) and progression of earlier lower grade BKPyV reactivation in 3 (17.6%). Clinical outcomes were similar for early- and late-onset BKPyVAN (P > .05 all comparisons). In a pooled analysis of prior studies of BKPyVAN in SPK recipients, 62.9% (17 of 27) were late-onset.

CONCLUSION

A significant proportion of BKPyVAN is late-onset, especially among SPK recipients, and supports a longer duration of BKPyV monitoring for SPK recipients than recommended in some guidelines.

BK virus replication in renal transplant recipients: Analysis of potential risk factors may contribute in reactivation

BACKGROUND

Considering the increasing problem of BK virus infection during post renal transplant surveillance, it is necessary to distinguish the main risk factors leading to reactivation of latent BK virus. Up to now, some probable risk factors have been investigated in some studies, but the results have been confusing and contradictory.

OBJECTIVES

The goal of the present study was to determine the frequency and potential risk factors that may play a role in BK polyomavirus reactivation and nephropathy.

STUDY DESIGN

In this cross-sectional study, 110 patients, who underwent consecutive transplantation between 2010 and 2013, were enrolled without preliminary screening. Urine and blood samples were taken, and quantitative Real-time PCR assay was used to detect and measure the viral load. Demographic and clinical characteristics of the patients who had BK viremia and/or viruria were documented.

RESULTS

Among 110 cases of renal transplant recipients, BK viruria and viremia were found in 54 (49%) and 22 people (20%) respectively. The pre-transplant durations of dialysis among patients with BK viruia were found longer in comparison to BK negative patients. Treatment with Tacrolimus (p=0.03) was found to be a risk factor for development of BK viruria. In patients with viruria and viremia the median creatinine levels were 1.45mg/dl and 1.35mg/dl respectively, which were higher than those in the patients with negative results for BK viruria (p=0.002) and viremia (p=0.02). Also, treatment with Cyclosporine could significantly increase the incidence of BK virus shedding in both urine and blood among patients who received it (p=0.01). Significant relation between reactivation of BK virus and other factors such as age, sex, acute rejection and diabetes was not found.

CONCLUSION

Based on our findings, the main potential risk factors for shedding of BK virus into urine in renal transplant recipients were prolonged pre-transplant dialysis and Tacrolimus regimen. Cyclosporine regimens could be considered as risk factor for both BK viruria and viremia. A significant correlation between BK virus replication and elevated creatinine level was seen among our patients.

Infection and chronic allograft dysfunction

With the advent of more potent immunosuppressive regimens, the incidence of acute rejection following renal transplantation has declined sharply in recent years. In spite of this, long-term graft outcomes remain suboptimal because of relentless attrition by cumulated insults to the allograft. As acute rejection rates have declined, other causes of graft injury and loss have recently emerged. Among these, infectious diseases remain a persistent threat and can be associated with allograft dysfunction. This group includes nephropathy due to polyoma (BK) virus infection, cytomegalovirus disease, and bacterial infection (the latter most commonly arising from the urinary tract). Rarer infectious causes of chronic allograft dysfunction include cryoglobulinemia associated with hepatitis C, Epstein-Barr virus-associated posttransplant lymphoproliferative disease, and direct cytotoxicity from adenoviral infection or parvovirus B19.