Progressive multifocal leukoencephalopathy (PML) typically affects the CNS white matter of the central nervous system. We present an human immunodeficiency virus-infected patient with polyomavirus JC infection restricted to granule cell neurons of the cerebellum and with corresponding neurological symptomatology. Magnetic resonance imaging demonstrated cerebellar atrophy without white matter lesions and stereotactic biopsy showed selective infection of the cerebellar granular cell layer, with preservation of Purkinje cells and absence of classic progressive multifocal leukoencephalopathy histopathology in underlying white matter. Evolution over 8 years was marked by symptomatic improvement corresponding to highly active antiretroviral therapy (HAART), with modest increase in CD4(+) T-cell counts. We propose to call this novel syndrome JCV granule cell neuronopathy (JCV GCN).

The role of JC virus (JCV)-specific CTL was explored in the immunopathogenesis of progressive multifocal leukoencephalopathy (PML). We identified a 9-aa epitope of the JCV capsid protein VP1, the VP1p100 peptide ILMWEAVTL, which is recognized by CTL of HLA-A2+ HIV+/PML survivors. We then constructed an HLA-A*0201/VP1p100 tetrameric complex that allowed us to assess by flow cytometry the PBMC of 13 PML patients and 11 control subjects for the presence of JCV-specific CTL. VP1p100-specific CTL were detected by tetramer binding in VP1p100-stimulated PBMC of five of seven (71%) PML survivors and zero of six PML progressors (p = 0.02). Two of three HIV+ patients with a leukoencephalopathy resembling PML, but with no virologic evidence of JCV infection, also had detectable VP1p100-specific CTL in their PBMC. PBMC of eight HIV+ patients with other neurologic diseases and healthy control subjects had no detectable JCV-specific CTL. These data suggest that the JCV-specific cellular immune response may be important in the containment of PML, and the tetramer-staining assay may provide a useful prognostic tool in the clinical management of these patients.

The polyomavirus JC (JCV) is the etiologic agent of progressive multifocal leukoencephalopathy (PML) and of JCV granule cell neuronopathy(JCV GCN). We present an HIV-negative patient who developed multiple cortical lesions, aphasia and progressive cognitive decline after chemotherapy for non-small-cell lung cancer. Brain biopsy and CSF PCR demonstrated JCV and she had a rapidly fatal outcome. Post-mortem analysis showed diffuse cortical lesions and areas of necrosis at the graywhite junction. Immunostaining revealed a productive JCV-infection of cortical pyramidal neurons, confirmed by electron microscopy, with limited demyelination. This novel gray matter syndrome expands the scope of JCV clinical presentation and pathogenesis.