BACKGROUND: The risk of @entity7578 ( @entity7578 ) caused by the @entity8315 (JCV) is increased in @entity1 with @entity15 receiving biological therapies. OBJECTIVES: To determine the seroprevalence of anti-JCV antibodies in Finnish @entity1 with @entity15 ( @entity15 ) and @entity922 and to assess the clinical risk factors for JCV seropositivity. METHODS: The JCV seroprevalence was analyzed in 503 @entity1 using a second-generation two-step ELISA. Sixty-seven @entity1 underwent longitudinal serological evaluation over 4.5  years. RESULTS: The overall seroprevalence of JCV was 57.4%. The seropositivity was higher in @entity1 than in @entity1 , tended to increase with age, and was not affected by different immunomodulatory therapies. However, in @entity1 with ongoing natalizumab treatment (n  =  72), the anti-JCV antibody screening index was lower than in @entity1 without such therapy [median 0.3 (range 0.1-3.1) vs 0.6 (0.1-3.1), respectively, P  =  0.01]. Over 4.5  years, 4/19 (21%) initially seronegative @entity1 converted to seropositivity, whereas 4/48 (8.3%) initially seropositive @entity1 reverted to seronegativity. Fluctuations in serostatus were observed in 3/67 @entity1 . CONCLUSION: The study confirmed a high anti-JCV antibody prevalence in @entity1 with @entity15 and its association with age and male gender but not with disease-modifying therapies. Our data suggest that therapy with natalizumab may cause a decrease in anti-JCV antibody levels, suggesting an immunosuppressive effect of natalizumab without an impact on JCV seroprevalence. The results of studies performed until now confirm the predictive value of anti-JCV antibody measurement in the assessment of @entity7578 risk; however, changes in serostatus need to be considered.

Anti-JC virus seroprevalence in a Finnish XXXX cohort.

@entity1 :: ('9606', 'Species') :: ['women', 'patients', 'men'] @entity8315 :: ('10632', 'Species') :: ['JC virus'] @entity15 :: ('MESH:D009103', 'Disease') :: ['MS', 'multiple sclerosis'] @entity922 :: ('MESH:D013568', 'Disease') :: ['clinically isolated syndrome'] @entity7578 :: ('MESH:D007968', 'Disease') :: ['progressive multifocal leukoencephalopathy', 'PML']
@entity15 :: (MESH:D009103,Disease) :: ['MS']
