title: Markers of JC virus infection in patients with multiple sclerosis under natalizumab therapy.
abstract: OBJECTIVE
  To evaluate the frequency of JC polyomavirus (JCPyV) infection and anti-JCPyV antibodies in patients with multiple sclerosis under natalizumab therapy.
  
  
  METHODS
  Presence of anti-JCPyV antibodies and JCPyV DNA was analyzed in 39 patients with relapsing-remitting multiple sclerosis undergoing natalizumab therapy. Anti-JCPyV antibodies were evaluated in serum by a 2-step virus-like particle-based ELISA assay (Stratify), and JCPyV DNA was evaluated in peripheral blood mononuclear cells, plasma, and urine by quantitative PCR. The anti-JCPyV antibodies were evaluated in serum samples collected at the same time or later than those collected for DNA analysis.
  
  
  RESULTS
  JCPyV DNA was detected in 59% of patients, and anti-JCPyV antibodies were present in 67%. JCPyV DNA occurred more often in blood than in urine. Anti-JCPyV antibodies were observed in 70% of the JCPyV-infected patients, and JCPyV DNA was detected in 50% of the patients without anti-JCPyV antibodies. When JCPyV DNA was investigated in blood and urine the frequency of infection was higher than previously described.
  
  
  CONCLUSIONS
  Under these experimental conditions, with respect to the observed frequency of JCPyV infection, the sensitivity of the anti-JCPyV antibody assay was lower than expected.
authors.affiliation: Department of Experimental and Clinical Medicine (V.C., S.G., F.M., A.A.) and Department of Neurosciences, Drugs and Child Health (E.M., L.M.), University of Florence; and Neurology 2 Division (A.R., C.M., L.M.), Careggi University Hospital, Florence, Italy.
authors.forename: Valeria
authors.initials: V
authors.lastname: Clausi
authors.affiliation: Department of Experimental and Clinical Medicine (V.C., S.G., F.M., A.A.) and Department of Neurosciences, Drugs and Child Health (E.M., L.M.), University of Florence; and Neurology 2 Division (A.R., C.M., L.M.), Careggi University Hospital, Florence, Italy.
authors.forename: Simone
authors.initials: S
authors.lastname: Giannecchini
authors.affiliation: Department of Experimental and Clinical Medicine (V.C., S.G., F.M., A.A.) and Department of Neurosciences, Drugs and Child Health (E.M., L.M.), University of Florence; and Neurology 2 Division (A.R., C.M., L.M.), Careggi University Hospital, Florence, Italy.
authors.forename: Eliana
authors.initials: E
authors.lastname: Magnani
authors.affiliation: Department of Experimental and Clinical Medicine (V.C., S.G., F.M., A.A.) and Department of Neurosciences, Drugs and Child Health (E.M., L.M.), University of Florence; and Neurology 2 Division (A.R., C.M., L.M.), Careggi University Hospital, Florence, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Repice
authors.affiliation: Department of Experimental and Clinical Medicine (V.C., S.G., F.M., A.A.) and Department of Neurosciences, Drugs and Child Health (E.M., L.M.), University of Florence; and Neurology 2 Division (A.R., C.M., L.M.), Careggi University Hospital, Florence, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Mechi
authors.affiliation: Department of Experimental and Clinical Medicine (V.C., S.G., F.M., A.A.) and Department of Neurosciences, Drugs and Child Health (E.M., L.M.), University of Florence; and Neurology 2 Division (A.R., C.M., L.M.), Careggi University Hospital, Florence, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Martelli
authors.affiliation: Department of Experimental and Clinical Medicine (V.C., S.G., F.M., A.A.) and Department of Neurosciences, Drugs and Child Health (E.M., L.M.), University of Florence; and Neurology 2 Division (A.R., C.M., L.M.), Careggi University Hospital, Florence, Italy.
authors.forename: Alberta
authors.initials: A
authors.lastname: Azzi
authors.affiliation: Department of Experimental and Clinical Medicine (V.C., S.G., F.M., A.A.) and Department of Neurosciences, Drugs and Child Health (E.M., L.M.), University of Florence; and Neurology 2 Division (A.R., C.M., L.M.), Careggi University Hospital, Florence, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Massacesi