Epstein-Barr virus seroreactivity, putative autoimmunity and axonal injury in pre-symptomatic multiple sclerosis

• Introduction: Multiple sclerosis (MS) and presymptomatic axonal injury appears to develop only after an Epstein-Barr virus (EBV) infection. Anoctamin2 (ANO2), a chloride channel expressed in glial cells and neurons, was identified as a possible MS autoantigen. We here examine serum neurofilament (sNfL), a comprehensive EBV seroreactivity and antibodies against ANO2 in pre-symptomatic MS.Objectives/Aims: To study whether the appearance of EBV seroreactivity in the pre-symptomatic phase of MS precedes cumulating MS-induced neuroaxonal damage and whether it is associated with an incipient autoreactivity against a reported MS autoantigen (ANO2).Methods: We performed a case-control study with presymptomatic serum samples identified through cross-linkage of the Swedish MS register and Swedish biobanks. We assayed serum antibodies against EBV nuclear antigen 1 (EBNA1), viral capsid antigen p18 (VCAp18), EBV glycoprotein 350 (gp350), anoctamin 2 (ANO2), and serum neurofilament light (sNfL) in 669 pre-MS cases and matched controls.Results: EBNA1 seroreactivity increased in the pre-MS group from 20–15 years before MS onset, followed by gp350 seroreactivity (p=0.001–0.002, 15–10 years before onset). This appeared before the elevation of sNfL in EBV seropositive pre-MS cases (p=8⋅10-5, 10–5 years before onset). No significant sNfL increase was observed in the EBV seronegative group (p=0.95). Pre-MS cases with the highest sNfL levels cumulated in the EBV seropositive group (p=0.038). ANO2 seropositivity appeared virtually only in the EBNA1 seropositive group, in 16.7 % of EBNA1 seropositive pre-MS samples and in 10.0 % of corresponding controls (p=0.001). Combined EBNA1 and ANO2 seropositivity showed a higher association with subsequent MS than EBNA1 independent of ANO2 (p=0.002–0.028). In the EBNA1 seropositive stratum, ANO2 seropositivity was associated with 26% higher sNfL.Conclusion: In presymptomatic MS an antibody response against EBV, associated with ANO2 autoimmunity, was detectable before elevated sNfL, which cumulated in the EBV seropositive group. ANO2 seropositivity was associated with higher sNfL. An increase in ANO2 seroreactivity did not appear until after EBV seroconversion, limited to a subgroup of the EBV seropositive stratum. Thus, this specific cross-reaction could contribute to MS pathogenesis in a subgroup. This further implicates EBV in the pathogenesis of MS.

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MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Neurologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Neurology (hsv//eng)

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