title: Reactivation of BK polyomavirus in patients with  multiple sclerosis receiving natalizumab therapy.
abstract: Natalizumab therapy in multiple sclerosis has been associated with JC polyomavirus-induced progressive multifocal leucoencephalopathy. We hypothesized that natalizumab may also lead to reactivation of BK, a related human polyomavirus capable of causing morbidity in immunosuppressed groups. Patients with relapsing remitting multiple sclerosis treated with natalizumab were prospectively monitored for reactivation of BK virus in blood and urine samples, and for evidence of associated renal dysfunction. In this cohort, JC and BK DNA in blood and urine; cytomegalovirus (CMV) DNA in blood and urine; CD4 and CD8 T-lymphocyte counts and ratios in peripheral blood; and renal function were monitored at regular intervals. BK subtyping and noncoding control region sequencing was performed on samples demonstrating reactivation. Prior to commencement of natalizumab therapy, 3 of 36 patients with multiple sclerosis (8.3%) had BK viruria and BK reactivation occurred in 12 of 54 patients (22.2%). BK viruria was transient in 7, continuous in 2 patients, and persistent viruria was associated with transient viremia. Concomitant JC and CMV viral loads were undetectable. CD4:CD8 ratios fluctuated, but absolute CD4 counts did not fall below normal limits. In four of seven patients with BK virus reactivation, transient reductions in CD4 counts were observed at onset of BK viruria: these resolved in three of four patients on resuppression of BK replication. No renal dysfunction was observed in the cohort. BK virus reactivation can occur during natalizumab therapy; however, the significance in the absence of renal dysfunction is unclear. We propose regular monitoring for BK reactivation or at least for evidence of renal dysfunction in patients receiving natalizumab.
authors: Department of Neurology, St Vincent's University Hospital, Elm Park, Dublin, Ireland. roisin.lonergan@st-vincents.ie
authors: Roisin M
authors: RM
authors: Lonergan
authors: Michael J
authors: MJ
authors: Carr
authors: Cillian F
authors: CF
authors: De Gascun
authors: Lisa F
authors: LF
authors: Costelloe
authors: Allison
authors: A
authors: Waters
authors: Suzie
authors: S
authors: Coughlan
authors: Marguerite
authors: M
authors: Duggan
authors: Katie
authors: K
authors: Doyle
authors: Sinead
authors: S
authors: Jordan
authors: Michael W
authors: MW
authors: Hutchinson
authors: William W
authors: WW
authors: Hall
authors: Niall J
authors: NJ
authors: Tubridy
mesh_terms: D000293:Adolescent; D000328:Adult; D000911:Antibodies, Monoclonal / Q000008:administration & dosage / Q000009:adverse effects*; D061067:Antibodies, Monoclonal, Humanized; D001739:BK Virus / Q000235:genetics* / Q000276:immunology; D016516:CD4-CD8 Ratio; D004279:DNA, Viral / Q000097:blood / Q000235:genetics; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016867:Immunocompromised Host; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000150:complications / Q000188:drug therapy / Q000276:immunology; D000069442:Natalizumab; D010802:Phylogeny; D027601:Polyomavirus Infections / Q000150:complications / Q000276:immunology* / Q000821:virology; D012008:Recurrence; D014412:Tumor Virus Infections / Q000150:complications / Q000276:immunology* / Q000821:virology; D014766:Viremia / Q000150:complications / Q000276:immunology / Q000821:virology; D055815:Young Adult
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D004279:DNA, Viral; D000069442:Natalizumab