Virus
BK virus
Transplant nephropathy and cystitis
bee-kay VY-rus
High-yield clue
BK virus reactivation causing nephropathy in kidney transplant and hemorrhagic cystitis after stem-cell transplant is the key clue.
Overview
A non-enveloped double-stranded DNA polyomavirus that establishes latency in the urinary tract and reactivates in transplant recipients, a classic example of opportunistic reactivation in immunosuppressed hosts.
Classification
- DNA virus
- Double-stranded circular DNA
- Non-enveloped
- Family Polyomaviridae (Human polyomavirus 1)
Lab & identification clues
- Urinary 'decoy cell' cytology concept
- Blood and urine PCR viral-load vocabulary
- Renal tubular epithelial tropism concept
- Latency in uroepithelium vocabulary
Associations
- Polyomavirus-associated nephropathy in kidney transplant
- Hemorrhagic cystitis after hematopoietic transplant
- Reactivation driven by immunosuppression
- Ureteral stenosis study association
Commonly confused with
- JC virus
- Adenovirus cystitis
Your notes
Original student-study summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment, dosing, or specimen-handling guidance.