BK Virus

Shmuel Shoham, M.D.


  • DNA polyomavirus, first isolated in 1971 from the urine of a renal transplant patient with ureteral stenosis whose initials were B.K.
  • Other members of the polyomavirus family:
    • JC virus, ~75% information shared genomically, KI polyomavirus, WU polyomavirus and trichodysplasia spinulosa-associated polyomavirus and Merkel cell polyomavirus.
  • Important viral components are large tumor antigen (T antigen), small tumor antigen (t antigen) and capsid proteins (VP1, VP2, VP3 and agnoprotein)
  • Subtypes: Subtype 1 is the most common, followed by subtype 4. Subtypes 3 and 4 are much less common. Serostatus of donor and recipient may impact risk for viral reactivation in kidney transplant.
    • PCR is best suited for detecting subtype 1. Some subtype 3 and 4 isolates have polymorphisms that may impact their detection, leading to falsely low viral load measurements

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Last updated: January 14, 2023