Abstract
BK virus (BKV) can cause BKV nephritis in renal transplant patients and has become a significant reason for graft loss in this decade. BKV is latent in the urogenital tract and most likely is transported with the donor kidney to recipients. BKV replication occurs in the nucleus of human renal proximal tubular cells (HRPTEC) and daughter viruses are delivered to other cells to spread infection. A few in vitro studies have been reported about the mechanism and kinetics of BKV infection. However, there are still a lot of unknown factors regarding BKV infection. This unit describes the handling of BKV, BKV propagation, determination of titer and ability to infect cells, as well as purification and labeling of BKV in order to analyze BKV cell entry.