Abstract:Objective：To investigate the incidence of BK virus infection in renal transplant recipients and to analyze the risk factors of BKV infection. Methods： The urine samples and peripheral blood samples of 63 renal transplant recipients were collected at 1, 2, 3, 4, 6 and 8 months after transplantation. A real-time fluorescent PCR procedure was used to detect BK virus DNA in the samples and the samples were divided into the following 3 groups according to the detection outcomes： UV^＋PV^＋ group （BKV DNA positive in both urine and blood samples）, UV^-PV^- group （BKV DNA positive in urine but negative in blood samples）, and UV^-PV^- group （BKV DNA negative in both urine and blood samples）. Urinary sediment smears of patients were checked for decoy cells and the decoy cells were subjected to cytological immunostaining. Renal graft biopsy was performed when a sample was highly suspected of BKVAN by its clinical manifestations. The age, cold ischemia time, hematodialysis duration, immunosuppressive agents, panel reactive antibody, and other clinical parameters were compared between the 3 groups and a Logistic regression was performed to analyze the risk factors of BK virus infection. Results： There were 19 （30.1 %） patients in UV^＋PV^- group, 9 （14.3%）in UV^＋PV^＋ group, and 35 in UV^-PV^- group. The median time for the first detection of BK virus was 4 months in UV^＋ PV^- group and 3 months in UV^＋ PV^＋ group. Decoy cells were detected in 39. 7% of the 63 patients and the positive rate of decoy cell immunostaining was 54. 3%. One patient showed no BDVAN manifestation in renal biopsy. Logistic regression found that the cold ischemia time was significantly related to the BKV DNA infection （P= 0. 048, OR = 1. 151 ）, but not to other parameters （ P = 0. 069 ）. Conclusion ： Real-time fluorescent quantitative PCR is a good way for detection of BKV infection after renal transplantation. The peak time for BKV shedding is 3-4 months after transplantation. Cold ischemia time may be one of the risk factors of BKV infection, and immunosupressive regiment may has no obvious influence on BK virus infection
