“Two more papers on JC virus and MS; this is becoming a mini-field of expertise. As you already know if you are JCV negative, i.e. you have not been exposed to the virus and hence don’t have the virus in your body the chance of you getting PML is very low. This does not mean it is zero as you can get exposed to virus as part of everyday life. In adults the seroconversion rate is quoted as being somewhere between 0.5% and 2% per year. The first study below looks at pediatric MSers and quotes a seroconversion rate of over 4% per year. Why? Maybe children and adolescents with MS are at higher risk of getting infected with the JC virus due to higher level of exposure? We think JCV is transmitted in urine and saliva. Maybe children/adolescents wash their hands less frequently and get exposed to saliva from different people, i.e. kiss more people, than adults? These results don’t change clinical practice in that if you are JCV negative and are on natalizumab you need you JCV status checked every 6 months and if you seroconvert you need to discuss strategies to de-risk the treatment by switching to an alternative agent.”
Epub 1: Huppke et al. JC virus antibody status in a paediatric multiple sclerosis cohort: Prevalence, conversion rate and influence on disease severity. Mult Scler. 2014 Jul.
BACKGROUND: Because of the emergence of novel therapies for MS and the associated increased risk of progressive multifocal leukoencephalopathy (PML), John Cunningham (JC) virus infection has become a focus of interest for neurologists. However, little is known about JC virus infection in paediatric MS to date.
OBJECTIVE: We aimed to analyze the prevalence of anti-JC virus antibodies, the conversion rate and the influence of the anti-JC virus antibody status on the clinical course in a large pediatric MS cohort.
METHODS: Anti-JC virus antibodies were analyzed in serum samples within six months of disease onset and during the course of the disease. Clinical data were extracted from a pediatric MS databank.
RESULTS: A total of 51.6% of 256 MSers were found to be positive for anti-JC virus antibodies at onset of disease. No correlation between antibody status and clinical course was seen. Analyzing 693 follow-up serum samples revealed high titer stability, and an annual conversion rate of 4.37% was seen.
CONCLUSION: No evidence was found that seropositivity for anti-JC virus antibodies influences the clinical course. Surprisingly, seroprevalence for anti-JC virus antibodies was more than twice as high as anticipated in this age group, raising the question of whether the infection increases the risk of MS development.
Epub 2: Delbue et al. JC virus urinary excretion and seroprevalence in natalizumab-treated multiple sclerosis patients. J Neurovirol. 2014 Jul 23.
Background: The risk of developing PML, as a consequence of infection/reactivation with JC virus (JCV), is consistent in natalizumab-treated MSers, with 430 cases of PML reported so far. The risk of PML is higher in JCV seropositive MSers, and it is recommended that only MSers without JCV antibodies should be enrolled in the treatment postulating that they do not have JCV infection.