Virus-specific antibody responses in multiple sclerosis patients treated with Ocrevus.

Multiple sclerosis (MS) is a demyelinating disease of the central nervous system. B cell-depleting therapy is highly efficient in treating patients with relapsing-remitting MS (RRMS), although the mechanisms behind reducing disease progression with this type of therapy is unknown. Virus infections are associated with the onset of MS and antibodies to these have previously been suggested to supplement MS diagnostics. Based on this, we aimed to investigate the effect of Ocrevus (OCR) (B cell depletion therapy) on selected virus antibody levels. Blood samples were collected from RRMS patients before (n = 13) and during OCR treatment (n = 29) and from healthy controls (HCs) (n = 15). Serum antibodies to virus antigens from Epstein-Barr virus (EBV), severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), Rubella virus, Measles virus, John Cunningham polyomavirus, Mumps virus, Merkel cell polyomavirus, Varicella zoster virus, Influenza A virus, Human herpes virus 6, and Cytomegalovirus were analyzed by enzyme-linked immunosorbent assay. EBV nuclear antigen 1 (EBNA1) IgG levels were elevated in RRMS patients compared to HCs independent of OCR treatment. However, no significant difference in virus antibody levels was observed following OCR treatment. Only SARS-CoV-2 spike protein IgG levels were significantly reduced following OCR treatment. The effect of OCR treatment on antibody levels may correlate with the time of infection. Only EBV EBNA1 IgG levels were significantly elevated RRMS patients at baseline compared to HCs, supporting that EBV infection is involved in the development of MS and confirming the diagnostic value of EBNA1 IgG.