1Amal Atrous, 1Saloua Mrabet, 1Amira Souissi, 1Lilia Hmissi, 1Firas Larnoaout, 1Mouna Ben Djebara, 1Amina Gargouri, 1Imen Kacem, 1Riadh Gouider

1Department of Neurology, Clinical Investigation Centre Neurosciences and Mental Health, University Hospital Razi, Manouba, Tunisia; 2Faculty of medicine, University Tunis El Manar, Tunis, Tunisia


Anti- John Cunningham virus (JCV) antibody index has been reported to correlate with progressive multifocal leukoencephalopathy (PML) risk in seropositive Multiple Sclerosis (MS) patients. Although it is reported that seroconversion occurs in approximately 2–15% of patients per year, there is insufficient evidence on long-term dynamics of anti-JCV antibody index. Our objective was to investigate the longitudinal evolution of anti-JCV antibody index in a cohort of Tunisian MS patients and to evaluate the impact of age, sex and disease modifying therapies (DMT) use in Anti-JCV antibody status.

Material(s) and Method(s):

We studied records of the patients diagnosed with MS according to 2017 Mc Donald criteria and followed at the MS Unit of the department of Neurology of Razi University Hospital in Tunis-Tunisia between 2018 and 2020, with or without DMT. We included patients for whom Anti-JCV antibody serological status and repetitive assessment of JCV antibody index were available.


One hundred patients were included in this study. Seventy-one of them were female. Median follow-up time was 36,19 months, with a median of 3 samples available per patient. At baseline, 49 % of patients were anti-JCV antibody positive with a median anti-JCV antibody index of 1.16. Twelve patients (12%) changed initial serostatus at least once during follow-up: 4% from negative to positive anti-JCV antibody status and 8% from positive to negative anti-JCV antibody status. Baseline anti-JCV antibody index was higher in patients remaining seropositive at follow-up compared to those reverting to seronegativity (1.94 vs. 0.89, p = 0.02). Only 6.1% of our patients did not receive DMT at time of JCV assessment. The 94% of patients were under Rebif (39%), under Avonex (37,4%) and under Natalizumab (46,5%). Natalizumab was stopped in 10 patients because of seroconversion in 4 of them and other side effects in 6 others. The type of DMT did not affect the anti-JCV antibody status. Moreover, no correlation was found between Baseline anti-JCV antibody index and sex or age. 60% of our patients had a second JCV blood sample with a median number of months between the first and second sample of 10,95 months with 91% of stability between the two assessments. 41% of our patients had a third JCV blood sample with 68,3 % of patients remaining negative.


Anti-JCV antibody index remained relatively stable over 3-year follow-up in our Tunisian cohort. Baseline anti-JCV antibody index was higher in positive seroconverters and was not affected by MS patients’ age or gender and the type of DMT use.