Different behaviour of BK-virus infection in liver transplant recipients

The molecular footprints of BK virus in the product of conception over the second and third gestational trimesters

OBJECTIVE

Prior studies have shown controversial results on the vertical transmission of BK virus (BKV). The present study aimed to assess the possibility of BKV vertical transmission from mother to fetus in the product of conception (embryo, fetuses, and/or placentas) over the three stages of pregnancy.

RESULTS

Of the 26 placental studied tissues, 6 were in the first trimester, and none of which were positive. Only one out of the 13 (7.7%) placental materials in the second trimester was positive. Only one out of 7 (14%) placental materials of the third trimester was positive. There were cases that no virus was detected in their placental but BKV was detected in their other tissues. Among 26 conceptuses, 17 (65%) were negative for BKV and 9 (34.6%) were positive, 7/13 (54%) were positive in the second, and 2/7 (29%) were positive in the third trimester fetuses. BKV was most frequently detected in the liver (eight cases), heart (three cases), and placenta (2 cases). There were cases that no virus was detected in their placental but BKV was detected in their other tissues.

A multivalent polyomavirus vaccine elicits durable neutralizing antibody responses in macaques

In 2019, there were about 100,000 kidney transplants globally, with more than a quarter of them performed in the United States. Unfortunately, some engrafted organs are lost to polyomavirus-associated nephropathy (PyVAN) caused by BK and JC viruses (BKPyV and JCPyV). Both viruses cause brain disease and possibly bladder cancer in immunosuppressed individuals. Transplant patients are routinely monitored for BKPyV viremia, which is an accepted hallmark of nascent nephropathy. If viremia is detected, a reduction in immunosuppressive therapy is standard care, but the intervention comes with increased risk of immune rejection of the engrafted organ. Recent reports have suggested that transplant recipients with high levels of polyomavirus-neutralizing antibodies are protected against PyVAN. Virus-like particle (VLP) vaccines, similar to approved human papillomavirus vaccines, have an excellent safety record and are known to induce high levels of neutralizing antibodies and long-lasting protection from infection. In this study, we demonstrate that VLPs representing BKPyV genotypes I, II, and IV, as well as JCPyV genotype 2 produced in insect cells elicit robust antibody titers. In rhesus macaques, all monkeys developed neutralizing antibody titers above a previously proposed protective threshold of 10,000. A second inoculation, administered 19 weeks after priming, boosted titers to a plateau of ≥ 25,000 that was maintained for almost two years. No vaccine-related adverse events were observed in any macaques. A multivalent BK/JC VLP immunogen did not show inferiority compared to the single-genotype VLP immunogens. Considering these encouraging results, we believe a clinical trial administering the multivalent VLP vaccine in patients waiting to receive a kidney transplant is warranted to evaluate its ability to reduce or eliminate PyVAN.

Infection, Rejection, and the Connection

Solid organ transplantation is a life-saving treatment for people with end-stage organ disease. Immune-mediated transplant rejection is a common complication that decreases allograft survival. Although immunosuppression is required to prevent rejection, it also increases the risk of infection. Some infections, such as cytomegalovirus and BK virus, can promote inflammatory gene expression that can further tip the balance toward rejection. BK virus and other infections can induce damage that resembles the clinical pathology of rejection, and this complicates accurate diagnosis. Moreover, T cells specific for viral infection can lead to rejection through heterologous immunity to donor antigen directly mediated by antiviral cells. Thus, viral infections and allograft rejection interact in multiple ways that are important to maintain immunologic homeostasis in solid organ transplant recipients. Better insight into this dynamic interplay will help promote long-term transplant survival.

Concomitant BK virus infection and visceral Leishmaniasis in a pediatric liver transplant recipient

BACKGROUND

Solid organ transplant recipients are vulnerable to various unusual infections. Visceral Leishmaniasis (VL) is a protozoal opportunistic infection, which may affect the immune-suppressed hosts and solid organ transplant recipients. The BK virus infection is an evolving challenge in kidney transplant recipients. However, there are very few reports of BK virus (BKV) nephropathy involving the native kidney in liver transplant recipients. To the best of our knowledge, this is the first report of the simultaneous occurrence of these rare infections in a liver transplant recipient.

CASE REPORT

The patient was a 9-year-old girl, a case of liver transplantation who presented with the incidental finding of proteinuria, azotemia, and cytopenia. Investigations revealed that she had concomitant BKV nephropathy and visceral leishmaniasis. Both infections were successfully treated.

CONCLUSION

BK virus should be considered as a cause of nephropathy in liver transplant recipients. The presenting features of fever, cytopenia, and splenomegaly in a post-transplant patient should remind of unusual infections such as VL other than the common post-transplant conditions.

Prospective analysis of BKV hemorrhagic cystitis in children and adolescents undergoing hematopoietic cell transplantation

BK virus is one of the most common causes of hemorrhagic cystitis (HC) in children undergoing hematopoietic cell transplantation (HCT). Viruses can be found in urine and serum samples of immunocompromised patients. Malignant diseases, age, cell source, day of granulocyte reconstitution, conditioning regimen, or use of total body irradiation may play an important role in BKV epidemiology, development of hemorrhagic cystitis course, and outcome. The aim of this study was to evaluate the incidence, clinical course, and risk factors for BKV-HC in children undergoing HCT. A total number of 133 patients who were prospectively tested for BKV colonization/infection were enrolled into this multicenter analysis. Episodes of BKV-HC occurred in 36/133 (27%) enrolled subjects. In a univariate analysis for BKV-HC incidence, the following factors were significant: age >5 years, peripheral blood transplantation, matched unrelated donor (MUD) transplantation, busulfan-cyclophosphamide-melphalan conditioning regimen, and acute myeloblastic leukemia (AML) diagnosis. Presence of acute graft-versus-host disease (aGVHD) in liver and gut GVHD was a significant risk factor of BKV-HC. No BKV-attributed deaths were reported. In multivariate analysis, the incidence of HC was significantly higher in patients with AML, age >5 years, MUD transplants, and children with GVHD. HC is a frequent complication after HCT among children causes prolonged hospitalization but rarely contributes to death. We identified risk factors of BKV-HC development in children, with focus on aGVHD: we concluded that excessive immune reaction connected with GVHD and immunosuppression drugs might play a pivotal role in the development of BKV-HC.

Native kidney BK virus nephropathy, a systematic review

BACKGROUND

There is a growing base of literature describing BK nephropathy (BKVN) in patients outside of the setting of kidney transplant. Previous systematic reviews of the literature have been limited by methodology or by the scope of patients included.

STUDY DESIGN AND METHODS

Systematic Review (Prospero # CRD42018088524).

SETTING & POPULATION

Patients without kidney transplant who had biopsy-proven BKVN.

SELECTION CRITERIA FOR STUDIES

Full-text articles that describe native BKVN patient cases.

ANALYTICAL APPROACH

Descriptive synthesis.

RESULTS

The search identified 630 unique articles of which 51 were included in the final review. Sixty-five cases (including two new cases presented in this review) were identified, all but one occurred in the setting of known immunosuppression.

LIMITATIONS

The primary limitation was the exclusion of studies that did not fulfill the stringent review criteria. We excluded reports with only a clinical diagnosis of BKVN, such as those with viruria and/or viremia without biopsy.

CONCLUSIONS

As of May 2018, there are 65 reported cases of BKVN in native kidneys. This represents the most comprehensive description of biopsy-proven BKVN in native kidneys to date. Evaluation for BK nephropathy should be considered in immunocompromised patients who exhibit unexplained renal failure.

BK virus-associated viruria and viremia in a patient with lymphangioleiomyomatosis after lung re-transplantation: A case report and review of the literature on BK virus infection post-lung transplantation

The BK virus (BKV) is a member of the polyomaviridae family of DNA viruses. BKV reactivates under a highly immunosuppressed state and causes renal dysfunction. In renal transplant patients, BKV infection leads to tubular impairment and loss of transplanted kidney grafts. However, few studies have reported on the relationship between BKV and lung transplantation. Adjustment of the dosage of immunosuppressants is needed in some cases, but the treatment method has not been established. Here, we report a case of BKV-associated viruria and viremia in a patient with lymphangioleiomyomatosis (LAM) after lung re-transplantation. A 44-year-old female refractory LAM patient who had undergone lung re-transplantation 3 months earlier was diagnosed with BKV-associated viruria and viremia. Urine cytology indicated decoy cells and the urine and serum polymerase chain reaction test was positive for BKV. As scheduled after re-transplantation surgery, immunosuppressive drugs were progressively reduced. This patient was considered to have experienced spontaneous BKV-associated viremia and viruria. Review of the literature suggested that 17%-42% of BKV-associated viruria cases have been reported after lung transplantation, but cases of BKV-associated nephropathy are rarely reported. Based on the present case, doctors involved in lung transplantation should monitor patients for BKV infection. Decoy cell monitoring by urine cytology is a useful screening method in the follow-up observation after lung transplantation. Early-stage interventions may prevent BKV-associated nephropathy even in patients who have developed BKV viremia, and sirolimus can be administered to patients with histories of BKV infection if they are carefully monitored.

Role of BK polyomavirus (BKV) and Torque teno virus (TTV) in liver transplant recipients with renal impairment

PURPOSE

Renal impairment is a common complication after liver transplantation (LT). While BK polyomavirus (BKV) has been linked to renal failure in kidney transplant recipients, Torque teno virus (TTV) is a surrogate marker for immunosuppression that does not have a clear association with any human disease. The impact of BKV and TTV on renal impairment after LT is unknown.

METHODOLOGY

In this retrospective study, urine and serum samples from 136 liver transplant recipients were screened for BKV and TTV by quantitative PCR. In addition, serum was screened for BKV-specific antibodies and the VP1 typing region was sequenced for BKV genotyping. All parameters were correlated with clinical data.Results/Key findings. BK viruria was detected up to 21 years after transplantation in 16.9 % of cases. BK viraemia was detected in 8.7 % of patients with BK viruria up to 4 years after LT. BKV-specific antibodies were detected in 93.6 % of all LT recipients and correlated with BKV viral load in urine. There was no correlation between renal impairment and the detection of BK DNA in urine (OR 0.983). TTV DNA was detected in 84.6 % of serum samples and in 66.6 % of urine samples. The TTV viral load in serum correlated with the BKV viral load but had no impact on renal impairment.

CONCLUSION

Our data indicate that the detection of BKV and TTV is not a risk factor for renal impairment after LT. A correlation of TTV and BKV viral load seems to be an indicator for the immune status of the host.

BK virus as a mediator of graft dysfunction following kidney transplantation

PURPOSE OF REVIEW

BK virus is a significant risk factor for kidney allograft dysfunction and loss among renal transplant recipients. Currently, there is no proven effective treatment except for the reduction of immunosuppression. In this review, we discuss diagnostic challenges and current treatment options for BK in kidney transplant recipients.

RECENT FINDINGS

Antiviral and antibiotic therapies have been employed for BK viraemia with variable efficacy. In addition, novel therapeutic regimens such as adoptive transfer of targeted T cells have been described as possible treatment options for recipients with BK nephropathy. BK can also be seen in the native kidneys of pancreas, heart, lung and liver transplant recipients, suggesting that BK screening measures should be employed to other solid organ transplant recipients.

SUMMARY

Early screening for BK combined with reduction of immunosuppression remains the mainstay of treatment for BK viraemia. New therapeutic advances demonstrate promise in vitro; however, the in-vivo efficacy will be demonstrated by future studies.

Hemorrhagic Cystitis in a Liver Transplant Recipient Secondary to BK Virus

The association between BK virus infection and hemorrhagic cystitis (HC) in hematopoietic stem cell transplant (HSCT) recipients is well established. However, BK virus-associated HC has not been described in liver transplant (LT) recipients. We present a case of BK virus-associated HC in a LT recipient. Our patient presented with worsening liver function tests 2 years after transplantation and was found to have acute cellular rejection. He was treated with increased immunosuppression and subsequently developed hematuria. He was eventually diagnosed with BK virus-associated HC.

BK nephropathy in the native kidneys of patients with organ transplants: Clinical spectrum of BK infection

Nephropathy secondary to BK virus, a member of the Papoviridae family of viruses, has been recognized for some time as an important cause of allograft dysfunction in renal transplant recipients. In recent times, BK nephropathy (BKN) of the native kidneys has being increasingly recognized as a cause of chronic kidney disease in patients with solid organ transplants, bone marrow transplants and in patients with other clinical entities associated with immunosuppression. In such patients renal dysfunction is often attributed to other factors including nephrotoxicity of medications used to prevent rejection of the transplanted organs. Renal biopsy is required for the diagnosis of BKN. Quantitation of the BK viral load in blood and urine are surrogate diagnostic methods. The treatment of BKN is based on reduction of the immunosuppressive medications. Several compounds have shown antiviral activity, but have not consistently shown to have beneficial effects in BKN. In addition to BKN, BK viral infection can cause severe urinary bladder cystitis, ureteritis and urinary tract obstruction as well as manifestations in other organ systems including the central nervous system, the respiratory system, the gastrointestinal system and the hematopoietic system. BK viral infection has also been implicated in tumorigenesis. The spectrum of clinical manifestations from BK infection and infection from other members of the Papoviridae family is widening. Prevention and treatment of BK infection and infections from other Papovaviruses are subjects of intense research.