BK Virus

MICROBIOLOGY

• 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