JC-virus seroconversion in multiple sclerosis patients receiving natalizumab

Mult Scler. 2014 Jun;20(7):822-9. doi: 10.1177/1352458513505353. Epub 2013 Sep 26.


Aim: The objectives of this study were to evaluate the rate of JC virus (JCV) seroconversion/seroreversion in a French cohort of multiple sclerosis (MS) patients receiving natalizumab (NTZ), describe the characteristics of this population, identify risk factors for JCV seropositivity and analyse the additional value of quantitative JCV serology results in this context.

Methods: MS patients from two French MS centres, whose JCV serological status in 2011 while receiving NTZ was known (n=357; first-generation enzyme-linked immunosorbent assay (ELISA) test (Gen1)), were proposed for inclusion in this study. We evaluated the rate of JCV seroconversion over a period of one year with a second-generation ELISA test (Gen2; n=303) and analysed the quantitative results. Multivariate analysis was performed to identify risk factors for JCV seropositivity.

Results: Among the patients with Gen2 JCV serology (n=303) that had been JCV-seronegative one year before (n=165), the rate of JCV seroconversion was 26.67% (44/165). We observed a higher proportion of anti-JCV antibody seroconverters (14.5%) than expected (≤3%) but also increasing index values of anti-JCV antibody over time.

Conclusion: Our data suggest that JCV reactivation occurs during NTZ therapy and leads to an increase in the anti-JCV antibodies titre, thus making them more easily detectable by the second-generation ELISA test.

Keywords: JC virus; Multiple sclerosis; natalizumab; progressive multiple leukoencephalopathy; quantitative results.

Publication types

  • Multicenter Study

MeSH terms

  • Adult
  • Antibodies, Viral / blood*
  • Biomarkers / blood
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • France
  • Humans
  • Immunocompromised Host
  • Immunosuppressive Agents / adverse effects*
  • JC Virus / immunology*
  • JC Virus / pathogenicity
  • Leukoencephalopathy, Progressive Multifocal / diagnosis
  • Leukoencephalopathy, Progressive Multifocal / immunology*
  • Leukoencephalopathy, Progressive Multifocal / virology
  • Male
  • Middle Aged
  • Multiple Sclerosis / diagnosis
  • Multiple Sclerosis / drug therapy*
  • Multiple Sclerosis / immunology
  • Natalizumab / adverse effects*
  • Opportunistic Infections / diagnosis
  • Opportunistic Infections / immunology*
  • Opportunistic Infections / virology
  • Risk Factors
  • Seroconversion*
  • Serologic Tests
  • Time Factors


  • Antibodies, Viral
  • Biomarkers
  • Immunosuppressive Agents
  • Natalizumab