This study reports that the JC virus tests for Tysbari manufacturer and the Tyruko manufacturer and implied that they are more or less the same based on their head to head study. However, there are other studies where there are differences notably at the lower end and the Tyruko JC virus test finds more people that have seen JC virus meaning they have been previously infected. Given that the number of people with the virus are increasing from the 50% that we were lead to believe, I ask why is the JC virus not the cause of MS? I have yet to get an argument from the EBVers. Anyway papers like this will help satisfy the regulators. I wonder what will happen with the anti-drug antibody assay and wonder how 55% for the assay (of persistent antibodies) by the manufacturers of Tyruko can be made into 6% for the assay by the manufacturers of Tysabri, because in the summary of product characteristics it states that if there are persistent anti-drug antibodies then people should switch treatment.
Chisari CG, Spampinato G, Crimì P, Ferraro E, Lo Fermo S, Cimino V, Zappia M, Patti F.Ther Adv Neurol Disord. 2025 Nov 12;18:17562864251374972
Background: Two principal methods for detecting anti-John Cunningham virus (JCV) antibodies are currently utilized in clinical practice: STRATIFY JCV
, an ELISA developed by Biogen, and IMMUNOWELL, a solid-phase ELISA assay by Polpharma Biologics/GenBio.
Objective: We aimed to evaluate the concordance between STRATIFY and IMMUNOWELL in detecting anti-JCV antibodies in a real-world population of patients with relapsing-remitting multiple sclerosis (RRMS) undergoing natalizumab therapy.
Design: This monocentric observational study screened all patients treated with natalizumab for at least 6 months, referring to the MS Center of the University Hospital of Catania.
Methods: Each patient’s serum was tested simultaneously using STRATIFY-2 (STRATIFY JCV DxSelect) and IMMUNOWELL assays. The qualitative results (positive/negative) were compared, and the index values were analyzed using Pearson’s correlation and Bland-Altman plots. Inter-method agreement was calculated using Cohen’s kappa coefficient.
Results: Among the 120 patients tested, 82 were positive and 31 negative with both STRATIFY and IMMUNOWELL. Four cases were STRATIFY-negative but IMMUNOWELL-positive, and three were the opposite. Overall concordance was 94.2%, with a Cohen’s Kappa of 0.86, indicating strong agreement. The index values showed strong correlation (Pearson r = 0.79, p < 0.001) and the coefficient of determination (r 2) was 0.62.
Conclusion: STRATIFY and IMMUNOWELL demonstrate a high level of agreement in the detection of anti-JCV antibodies in patients with RRMS receiving natalizumab. IMMUNOWELL may serve as a reliable complementary method, especially in cases where borderline serostatus could influence therapeutic strategy. Regular and accurate monitoring of JCV status remains essential for guiding long-term treatment safety and optimizing individual patient outcomes.
Plain language summary
Comparing two blood tests to assess PML risk in MS patients treated with natalizumab. Natalizumab is a medication used to treat relapsing-remitting multiple sclerosis (RRMS), but it can increase the risk of a rare brain infection called progressive multifocal leukoencephalopathy (PML), caused by the JC virus (JCV). To help assess this risk, doctors test patients for antibodies against JCV in their blood. Two main tests are available to detect these antibodies: STRATIFY JCV and IMMUNOWELL. This study compared how well these two tests agree in real-world patients receiving natalizumab. Researchers tested blood samples from 120 patients using both tests at the same time. They found that the results matched in over 94% of cases, showing strong agreement. The few differences happened mostly in borderline cases, where the antibody levels were close to the cutoff point between negative and positive. This suggests that IMMUNOWELL is a reliable alternative to the standard STRATIFY JCV test. Using either test can help doctors monitor patients’ JCV status and make safer treatment decisions.
COI: Multiple
Disclaimer> My views
Source: multiple-sclerosis-research.org