Anti-John Cunnigham virus antibody prevalence in multiple sclerosis patients: baseline results of STRATIFY-1.

OBJECTIVE A study was undertaken to define the prevalence of anti-JC virus (JCV) antibodies in multiple sclerosis (MS) patients and to evaluate the analytical false-negative rate of a 2-step anti-JC virus antibody assay. METHODS STRATIFY-1 is an ongoing, longitudinal, observational study of relapsing MS patients in the United States who are being treated or considering treatment with natalizumab. Baseline serum and plasma samples were collected for anti-JC virus antibody detection using an analytically validated, 2-step, virus-like particle-based enzyme-linked immunosorbent assay. Urine was collected for JC virus DNA detection. RESULTS At baseline (n = 1,096), overall anti-JC virus antibody prevalence was 56.0% (95% confidence interval [CI], 53.0-59.0) in STRATIFY-1 patients, with an assay false-negative rate of 2.7% (95% CI, 0.9-6.2). Prevalence was significantly lower in females (53.4%; 95% CI, 49.9-56.8) than males (64.3%; 95% CI, 58.2-70.0) and increased with age, p = 0.0019 and p = 0.0001, respectively. Prevalence was similar in patients regardless of natalizumab exposure or prior immunosuppressant use, p = 0.9709 and p = 0.6632, respectively. STRATIFY-1 results were generally consistent with those observed in another large North American cohort, TYGRIS-US (n = 1,480). INTERPRETATION Baseline results from STRATIFY-1 are consistent with other studies utilizing this assay that demonstrate a 50 to 60% prevalence of anti-JC virus antibodies, a low false-negative rate, and an association of increasing age and male gender with increasing anti-JC virus antibody prevalence. Neither natalizumab exposure nor prior immunosuppressant use appear to affect prevalence. Longitudinal data from STRATIFY-1 will confirm the stability of anti-JC virus antibody prevalence over time.