Pegivirus-Associated Encephalomyelitis in Immunosuppressed Patients

 This Correspondence article describes a cluster of four immunosuppressed patients who developed a distinct form of progressive encephalomyelitis now termed pegivirus-associated encephalomyelitis (PAEM) linked to human pegivirus type 1 (HPgV-1). All patients exhibited progressive optic neuropathy and long-segment myelitis, with strikingly consistent MRI features: bilateral T2 hyperintensities in the anterior visual pathways, corticospinal tracts, and posterior spinal columns. High-throughput sequencing identified HPgV-1 RNA in cerebrospinal fluid, serum, and postmortem brain tissue. Full genome sequencing revealed viral compartmentalization within the central nervous system, supporting a causative role. Histopathology revealed inflammation and T-cell/macrophage infiltration. Two patients died; the remaining two were left severely disabled. The findings suggest HPgV-1 neurotropism and raise awareness of a potentially underrecognized cause of CNS disease in immunocompromised individuals.

 This Correspondence article describes a cluster of four immunosuppressed patients who developed a distinct form of progressive encephalomyelitis now termed pegivirus-associated encephalomyelitis (PAEM) linked to human pegivirus type 1 (HPgV-1). All patients exhibited progressive optic neuropathy and long-segment myelitis, with strikingly consistent MRI features: bilateral T2 hyperintensities in the anterior visual pathways, corticospinal tracts, and posterior spinal columns. High-throughput sequencing identified HPgV-1 RNA in cerebrospinal fluid, serum, and postmortem brain tissue. Full genome sequencing revealed viral compartmentalization within the central nervous system, supporting a causative role. Histopathology revealed inflammation and T-cell/macrophage infiltration. Two patients died; the remaining two were left severely disabled. The findings suggest HPgV-1 neurotropism and raise awareness of a potentially underrecognized cause of CNS disease in immunocompromised individuals.