Virus
JC virus
Cause of PML in immunosuppression
jay-see VY-rus
High-yield clue
Reactivated JC virus causing demyelinating PML in profoundly immunosuppressed patients is the core clue.
Overview
A small non-enveloped double-stranded DNA polyomavirus that stays latent in most adults and can reactivate in severely immunosuppressed hosts to cause progressive multifocal leukoencephalopathy (PML).
Classification
- DNA virus
- Double-stranded circular DNA
- Non-enveloped
- Family Polyomaviridae (Human polyomavirus 2)
Lab & identification clues
- Oligodendrocyte tropism concept
- CSF PCR detection vocabulary
- White-matter demyelination imaging vocabulary
- Enlarged 'ground-glass' oligodendrocyte nuclei concept
Associations
- Progressive multifocal leukoencephalopathy (PML)
- Reactivation in advanced HIV/AIDS
- Association with certain immunomodulatory therapies
- Latency in kidney and lymphoid tissue
Commonly confused with
- BK virus
- Cytomegalovirus encephalitis
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.