Inhibitory interactions between BK and JC virus among kidney transplant recipients.

BK and JC polyomaviruses can reactivate after transplantation, causing renal dysfunction and graft loss. The incidence of JC reactivation after renal transplant is not well understood. Here, we characterized JC reactivation using samples collected during the first year after transplantation from 200 kidney recipients. We detected BK and JC viruses in the urine of 35 and 16% of transplant recipients, respectively. The median viral load in the urine was 400 times higher for BK virus than JC virus. The presence of BK viruria made concurrent JC viruria less likely: JC viruria was detected in 22% of non-BK viruric recipients compared with 4% of BK viruric recipients (P=0.001). The co-detection rate was 1.5%, which is less than the expected 5.6% if reactivation of each virus was independent (P=0.001). We did not observe JC viremia, JC nephropathy, or progressive multifocal leukoencephalopathy. The onset of JC viruria was associated with donor, but not recipient, JC-specific antibody in a titer-dependent fashion and inversely associated with donor and recipient BK-specific antibody. Donor and recipient JC seropositivity did not predict BK viruria or viremia. In conclusion, among renal transplant recipients, infection with one polyomavirus inversely associates with infection with the other.

BK virus antibody titers and intensity of infections after renal transplantation.

BACKGROUND: The mean urine BK viral load in kidney transplant recipients increases with the intensity of infection as the infection progresses from transient viruria to sustained viremia. OBJECTIVES: This study investigated whether the intensity of infection is associated with the humoral immune response. STUDY DESIGN: We measured BKV-specific IgG antibody titers in stored samples obtained serially over a 1-year period from 70 kidney transplant recipients with BKV infection and 17 control recipients without active BKV infection. RESULTS: The mean pre-transplant BKV antibody level was lower in recipients who developed viremia than the mean level in those who never developed viremia (p=0.004). Mean antibody titers in recipients who never showed evidence of active BKV infection rose slightly after transplant despite immunosuppression. The magnitude of the rise in the mean antibody titers in recipients who developed active BKV infection correlated with the intensity of infection (p<0.001). CONCLUSIONS: The mean antibody level increased in accordance with the intensity of the infection post-transplant. Pre-transplant seropositivity did not protect against sustained viremia and the antibody response was not associated with clearance of the virus.

BK virus nephropathy and kidney transplantation.

Nephropathy from BK virus (BKV) infection is an evolving challenge in kidney transplant recipients. It is the consequence of modern potent immunosuppression aimed at reducing acute rejection and improving allograft survival. Untreated BKV infections lead to kidney allograft dysfunction or loss. Decreased immunosuppression is the principle treatment but predisposes to acute and chronic rejection. Screening protocols for early detection and prevention of symptomatic BKV nephropathy have improved outcomes. Although no approved antiviral drug is available, leflunomide, cidofovir, quinolones, and intravenous Ig have been used. Retransplantation after BKV nephropathy has been successful.

Donor origin of BK virus in renal transplantation and role of HLA C7 in susceptibility to sustained BK viremia.

In a previous study, we performed serial BK virus (BKV), polymerase chain reaction (PCR) and detected active BKV infection in 70 (35.4%) of 198 renal transplant recipients. In the current study, pre-transplant donor and recipient samples were analyzed for BKV antibody titer and HLA alleles. Donor antibody titer was inversely proportional to onset of viruria, p<0.001, directly proportional to duration of viruria, p=0.014 and directly proportional to peak urine viral titer p=0.005. Recipient pairs receiving kidneys from the same donor were concordant for BKV infection, p=0.017, and had matched sequences of segments of the NCCR and VP1 genes that tended to vary among recipients of kidneys from different donors. We did not see an association of HLA A, B, or DR, HLA allele mismatches or total HLA mismatches and BK infection. However, all 11 recipients with sustained BK viremia received kidneys from donors lacking HLA C7, and 10 recipients also lacked C7. These findings derive from the largest and most comprehensive prospective study of BKV infection in renal transplant recipients performed to date. Our data support donor origin for early BKV infection in kidney transplant recipients, and suggest that a specific HLA C locus may be associated with failure to control BKV infection.

A randomized, prospective, pharmacoeconomic trial of tacrolimus versus cyclosporine in combination with thymoglobulin in renal transplant recipients.

BACKGROUND: To date, the clinical trials of tacrolimus (TAC) versus cyclosporine modified (CsA), have not defined which agent is more cost-effective for immunosuppression in renal transplant recipients especially in a quadruple immunosuppressive regimen. METHODS: The objective of this randomized, prospective study was to compare the clinical and economic outcomes of TAC versus CsA, in a regimen that consisted of Thymoglobulin induction, an antimetabolite, and prednisone. Between December 2000 and October 2002, 200 patients were enrolled and randomized in a 2:1 fashion (TAC n=134, CsA n=66). RESULTS: At 1 year, acute rejection (4% TAC vs. 6% CsA), patient survival (TAC 99% vs. CsA 100%), and graft survival (95% TAC versus 100% CsA, P=0.059) were similar. Serum creatinine levels were lower in the TAC group compared with the CsA group (1.3+/-0.3 vs. 1.6+/-0.7 mg/dL, P=0.03). The incidence of CMV infection was similar between the groups and two patients, both in the TAC arm, developed malignancy. Anti-hypertensive requirement (32% TAC vs. 32% CsA) and the incidence of posttransplant diabetes mellitus (4% TAC vs. 2% CsA) were similar. Pretransplant, fewer TAC patients received dyslipidemia treatment (40% TAC vs. 67% CsA, P=0.0005), while more CsA patients were able to discontinue these medications posttransplant (absolute change 25% TAC vs. 47% CsA). Total 12-month medication costs were similar (17,723 +/- 11,647 dollars TAC vs. 16,515 +/- 10,189 dollars CsA). CONCLUSIONS: When combined with Thymoglobulin induction, an antimetabolite, and corticosteroids, TAC and CsA are comparable in safety, efficacy, and cost in renal transplantation.

Tularemia in a kidney transplant recipient: an unsuspected case and literature review.

Tularemia is a zoonotic infection that has rarely been reported in transplant recipients. The authors present a case of unsuspected tularemia in a kidney transplant patient that was diagnosed by isolation of Francisella tularensis in the blood. The patient was treated successfully with antibiotics. During diagnostic workup, a laboratory technician was exposed to tularemia by inhalation of the culture plate and received postexposure prophylaxis. This report emphasizes the importance of exposure history in the investigation of fever in an immunocompromised host and the special precautions needed when a virulent infectious organism is suspected.

Incidence of BK with tacrolimus versus cyclosporine and impact of preemptive immunosuppression reduction.

Our purposes were to determine the incidence of BK viruria, viremia or nephropathy with tacrolimus (FK506) versus cyclosporine (CyA) and whether intensive monitoring and discontinuation of mycophenolate (MMF) or azathioprine (AZA), upon detection of BK viremia, could prevent BK nephropathy. We randomized 200 adult renal transplant recipients to FK506 (n = 134) or CyA (n = 66). Urine and blood were collected weekly for 16 weeks and at months 5, 6, 9 and 12 and analyzed for BK by polymerase chain reaction (PCR). By 1 year, 70 patients (35%) developed viruria and 23 (11.5%) viremia; neither were affected independently by FK506, CyA, MMF or AZA. Viruria was highest with FK506-MMF (46%) and lowest with CyA-MMF (13%), p = 0.005. Viruria >/= 9.5 log(10) copies/mL was associated with a 3-fold increased risk of viremia and a 13-fold increased risk of sustained viremia. After reduction of immunosuppression, viremia resolved in 95%, without increased acute rejection, allograft dysfunction or graft loss. No BK nephropathy was observed. Choice of calcineurin inhibitor or adjuvant immunosuppression, independently, did not affect BK viruria or viremia. Viruria was highest with FK506-MMF and lowest with CyA-MMF. Monitoring and preemptive withdrawal of immunosuppression were associated with resolution of viremia and absence of BK nephropathy without acute rejection or graft loss.