Clinical Study On BK Virus Infection More Than One Year After Renal Transplantation

Objective:To study BK virus infection and its effect on renal allograft function in renaltransplant recipients more than one year after transplantation and analyse risk factors ofBK virus infection.Methods:From May to October in2013,167cases of kidney recipients in PLA309Hospital werecollected in this study.Regularly following up for six months and taking urinespecimens and blood samples every two months, we recorded their gender, age, bodymass index (BMI), surgery time,immunosuppressive regimen, source for kidney renalfunction and asked whether they had been in the presence or absence of diabetes,delayed graft function recovery (DGF), steroid pulse therapy and recent infections.According to the BKV DNA load detected by BKV DNA detection kit and fluorescencequantitative real-time PCR technology,we divided recipients into four groups:viremia,consecutive viruria, transient viruria and negative control. Measurement data using t test,Ftest or rank sum test,count data using the chi-square test or rank sum test,the data wasanalysed by SPSS16.0. Renal function was compared in four groups and risk factorswere analysed by logistic regression.Results:(1)Viremia,consecutive viruria and transient viruria incidence rates of the167recipients were3.6%(6/167),6.6%(11/167),8.9%(15/167).Incidence rate of consecuti-ve viruria gradually declined with postoperative time (1to3years:12.8%,3to5years:4.0%,5to10years:3.1%;10years or more:0%).the virus load of consecutive viruria wasobviously higher than viremia (2×109vs2.8×106copies/ml,P=0.003)and transient viruria(2×109vs2.6×106copies/ml,P=0.001).(2) Serum creatinine values of viremia in follow-up were significantly higher thanthem of consecutive viruria (203.5±38.6umol/L vs125.8±41.7umol/L,P=0.007),transie-nt viruria (203.5±38.6umol/L vs92.7±26.4umol/L,P=0.000) and negative control (203.5±38.6umol/L vs111.3±59.2umol/L,P=0.000).Changes in serum creatinine value of vi-remia(Follow-up creatinine minus the discharge creatinine) were also significantly higher than them of consecutive viruria (87.5±25.1umol/L vs40.4±38.1umol/L,P=0.002),transient viruria (87.5±25.1umol/L vs8.3±11.9umol/L, P=0.000) and negative control(87.5±25.1umol/L vs14.0±24.7umol/L,P=0.000).In addition,changes in serumcreatinine value of consecutive viruria were significantly higher than them of transientviruria (40.4±38.1umol/L vs8.3±11.9umol/L,P=0.015) and negative control (40.4±38.1umol/L vs14.0±24.7umol/L,P=0.012).(3) Univariate analysis showed that recipient age, gender, body mass index, typeof donor kidney, diabetes mellitus before and after surgery, whether to use the ATGimmune induction, whether received steroid pulse therapy, with or without DGF, therecent other infection had no correlation with BK virus infection. Time aftertransplantation and BK virus infection was negatively correlated (r=-0.174,P=0.025);compared to CsA,FK506administration based immunosuppressive regimen waspositively correlated with BK virus infection (r=0.179,P=0.024).CNI drug concentrationin stratified, hierarchical analysis showed FK506concentration (concentration in thevalley is bounded6ng/ml) had no correlation with BK virus infection, while CsAconcentration (concentration in the valley is bounded150ng/ml) was negativelycorrelated with BK virus infection. In combination regimen of immunosuppressivedrugs indicators stratified, hierarchical analysis showed FK506+MZR+Pred orCsA+MMF+Pred had no correlation with BK virus infection, while FK506+MMF+Predtriple immunosuppressive regimen still had positively correlation with BK virusinfection (r=0.186,P=0.030), CsA+MZR+Pred BK virus program had a negativecorrelation (r=-0.177,P=0.016). Multivariate analysis showed that If recipients whowere one or two years after transplantation had high valley drug concentrations(FK506>6ng/ml or CsA>150ng/ml),the risk of BK virus infection obviously increased.(OR=9.375,95%CI=1.035~84.90,P=0.047).Conclusion:There is a high incidence rate of BK virus infection in kidney recipients aftertransplantation between one year and three years.Viremia and consecutive viruria is animportant cause of graft dysfunction. If recipients who were one or two years aftertransplantation had high valley drug concentrations (FK506>6ng/mlor CsA>150ng/ml),t-he risk of BK virus infection obviously increased.