BK Virus Nephropathy After Kidney Transplantation and Its Diagnosis Using Urinary Micro RNA.

BK virus-associated nephritis (BKVAN) is an important cause of graft loss in renal transplant recipients B K viremia occurs in up to 30% of renal transplant recipients. Since the discovery of BKV in 1971, effective prophylaxis and treatment have not been established, and it is not uncommon for a transplant kidney to be lost without cure of BKVAN. BK virus infection is reactivated when cellular immunity is suppressed, which is often during the first year after kidney transplantation when cellular immunity is most suppressed. Clinically, it is caused by reactivation of latent infection or new infection from the donor kidney, leading to viremia, viremia, and transplant nephropathy. BK virus nephropathy is currently diagnosed definitively by measuring the amount of BK virus DNA in the blood and proving SV40-positive cells in transplant kidney tissue obtained by transplant kidney biopsy, but the time required for diagnosis and the low sensitivity of immunohistochemistry using antibodies are problematic. Therefore, we investigated whether the diagnosis of BK virus nephropathy could be made earlier by searching for miRNAs in the urine of renal transplant recipients.