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
Frequently asked questions
What is JC virus?
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).
What are the lab clues for JC virus?
Lab clues for JC virus include Oligodendrocyte tropism concept, CSF PCR detection vocabulary, White-matter demyelination imaging vocabulary, and Enlarged 'ground-glass' oligodendrocyte nuclei concept.
What is JC virus commonly confused with?
JC virus is commonly confused with BK virus and Cytomegalovirus encephalitis.
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.