More than 10 million US military personnel who were on active duty were examined longitudinally. MS is a central nervous system-originating autoimmune condition marked by inflammatory demyelinating lesions. On the cause of MS, there is no universal agreement. Multiple factors, including genetic and environmental ones, can affect MS, which is a complex illness. MHC II (major histocompatibility class II) and MHC I (major histocompatibility class I) alleles are the key genetic variables linked to MS risk. Furthermore, more than 200 genetic loci have been found to be linked to an increased risk of developing MS, however only a small number of the identified genetic locus's specific genes or biological processes have been investigated. The EBV status of the 107 matched controls and 35 MS cases was examined during the follow-up in order to clarify the relationship between EBV infection and the start of MS. Seroconversion was found to be considerably higher in those who got MS. However, the population that eventually developed MS symptoms and those who did not had comparable seroconversion rates for cytomegalovirus (CMV), the negative control virus. Additionally, the scientists discovered that the risk ratios for MS were 32.4 and 26.5, respectively, by contrasting EBV seroconversion and EBV-positive rates to EBV-negative rates. EBV infection occurs prior to the beginning of MS, further demonstrating the strong correlation between EBV infection and a higher chance of developing MS. A sensitive biomarker of neurodegeneration, serum neurofilament light chain (sNfL) may also be a biomarker of MS process beginning. Bjornevik et al. found amounts of sNfL in serum samples from 25 MS cases and 79 controls at various time points of EBV infection, further elucidating the temporal association between EBV infection and MS. Only after EBV infection compared to before EBV infection did sNfL levels in MS patients and controls differ considerably. The findings also suggested that EBV infection occurs before to the start of MS, before sNfL increase. The finding supports the idea that EBV infection is uniquely linked to an increased risk of MS and refutes the idea that a second attack from other viruses may have a significant impact on the aetiology of MS. The three clinical stages of MS are pre-clinical, relapsing-remitting (RR), and progressive. The RR stage is characterized by a notable relapse and remission course, while the progressive stage typically develops from the relapsing stage. EBV probably plays a role throughout the entire clinical course of MS and may have various roles in different stages of the disease. More than ten immunotherapy medicines for MS have been approved by the FDA as a result of our growing understanding of the immunological mechanism underlying MS. One of the best treatments for MS is anti-CD20 monoclonal antibody. Anti-CD20 monoclonal antibody, however, does not completely eliminate the offspring of its targeting circulating memory B cells and plasma cells that do not express CD20. Additionally, the fact that people who are EBV negative have a very low risk of developing MS shows that EBV infection and MS risk are related, and an EBV vaccine may one day be created to protect against MS. Overall, this study demonstrates that EBV infection is a cause of MS but not one of its effects.

Reference: - https://www.nature.com/articles/s41392-022-01100-0.pdf