Viral encephalitis Unusual JC virus infection JC encephalitis Progressive multifocal leukoencephalopathy (PML) JC virus encephalitis Encephalitis caused by JC polyomavirus infection, typically presenting as progressive multifocal leukoencephalopathy (PML). JC virus encephalitis is an opportunistic CNS infection typically seen in severe T-cell deficiencies and post-transplant patients. It often presents as Progressive Multifocal Leukoencephalopathy (PML) and has been specifically described in DOCK8 deficiency and Hyper-IgM syndrome. Clinical manifestations typically include progressive neurological deficits, cognitive impairment, and ataxia. Encephalitis caused by a Human polyomavirus 2 infection