JC virus VP1 loop-specific polymorphisms are associated with favorable prognosis for progressive multifocal leukoencephalopathy

Serena Delbue, Emanuela Branchetti, Simone Bertolacci, Eleonora Tavazzi, Enrico Marchioni, Renato Maserati, Giulia Minnucci, Sara Tremolada, Gianluca Vago, Pasquale Ferrante

Research output: Contribution to journalArticlepeer-review


JC virus (JCV) is a human polyomavirus that causes progressive multifocal leukoencephalopathy (PML), a fatal demyelinating disease that mainly affects immunocompromised subjects. Since its discovery, PML has been considered a rapidly progressing fatal disease; however, amino acid substitutions in the capsid viral protein have recently been tentatively associated with changes in PML clinical course. In order to provide more insight to PML pathogenesis and identify potential prognostic markers, seven cerebrospinal fluid (CSF) samples and four brain autopsy samples were collected from patients afflicted with PML with different clinical courses (fast- and slow-progressing), and the JCV VP1 coding region was amplified, cloned, and sequenced. In addition, urine samples were collected and analyzed from nine patients with PML or other neurological diseases (ONDs) as a control group. Sequencing analysis of the genomic region encoding the VP1 outer loops revealed polymorphic residues restricted to four positions (74, 75, 117, and 128) in patients with slow PML progression, whereas no significant mutation was found in JCV isolated from urine. Collectively, these data show that JCV VP1 loop mutations are associated with a favorable prognosis for PML. It is therefore possible that slower progression of PML may be related to the emergence of a less virulent JCV strain with a lower replication rate.

Original languageEnglish
Pages (from-to)51-56
Number of pages6
JournalJournal of NeuroVirology
Issue number1
Publication statusPublished - 2009


  • Amino acid substitutions
  • Disease progression
  • JC virus
  • PML

ASJC Scopus subject areas

  • Virology
  • Clinical Neurology
  • Cellular and Molecular Neuroscience
  • Neurology


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