This episode of This Week in Virology reviews compelling new evidence linking Epstein-Barr virus (EBV) infection to the development of multiple sclerosis (MS). The discussion begins with a retrospective analysis of a 1954 paper by Dorothy Horstmann, which first established the presence of poliovirus in the blood (viremia) during early infection, illustrating the evolution of virological research methods.
The core of the episode focuses on two recent, landmark papers. The first is a major epidemiological study from Science that analyzed a cohort of over 10 million U.S. military personnel over 20 years. This research found an exceptionally strong association, revealing that the risk of developing MS increased 32-fold after EBV infection, providing powerful evidence that EBV is a primary trigger for the disease.
Complementing this finding, the hosts review a mechanistic study from Nature that uncovers a likely biological cause: molecular mimicry. Researchers found that B cells in the cerebrospinal fluid of MS patients produce antibodies that recognize the EBV protein EBNA1. Crucially, these same antibodies cross-react with a human protein, GlialCAM, which is expressed on glial cells in the brain. The episode explores how this cross-reactivity, influenced by genetic predisposition (HLA types) and post-translational modifications, provides a direct link from the anti-viral immune response to autoimmune-mediated nerve damage. The hosts conclude by discussing the profound implications of these findings, including the potential for an EBV vaccine to prevent MS.
Unraveling the Viral Trigger for MS: A Deep Dive into EBV and Autoimmunity
5:14 Historical Context: The episode begins by examining a 1954 paper by Dorothy Horstmann that discovered viremia (virus in the blood) in early polio infection. This work, which relied on monkeys and early cell cultures, set the stage for understanding how viruses can spread from the gut to the nervous system.
33:12 The EBV-MS Connection: The hosts introduce the central topic: the long-suspected but difficult-to-prove link between Epstein-Barr virus (EBV) and multiple sclerosis (MS). Because EBV infects over 95% of adults, establishing it as the cause of a rarer disease like MS has been a major challenge.
40:05 A Groundbreaking Study: A key paper from Science is discussed, which analyzed a cohort of over 10 million U.S. military personnel over 20 years. Using a repository of 62 million archived serum samples, researchers could track individuals' EBV infection status over time relative to an MS diagnosis.
45:54 Overwhelming Evidence: The study's primary finding was a 32-fold increased risk of developing MS after infection with EBV. Of the 801 MS cases studied, all but one were infected with EBV before their MS diagnosis, providing the strongest epidemiological evidence to date for a causal link.
47:30 A Crucial Control: To ensure the effect was specific to EBV, researchers also tested for Cytomegalovirus (CMV), another common herpesvirus. They found no association between CMV infection and MS, reinforcing that the trigger is specific to EBV.
57:34 The Mechanism: Molecular Mimicry: A second paper from Nature provides a biological explanation for the link. The leading hypothesis is molecular mimicry, where the immune system makes antibodies to fight a virus, but these antibodies accidentally recognize a similar-looking human protein.
1:10:55 A Specific Viral Target: Researchers analyzed antibodies from the cerebrospinal fluid of MS patients and found they consistently target a specific EBV protein called EBNA1 (Epstein-Barr Nuclear Antigen 1).
1:14:28 The Cross-Reaction: The crucial discovery was that these same anti-EBNA1 antibodies also bind tightly to a human protein called GlialCAM (Glial Cell Adhesion Molecule), which is present on the surface of important brain support cells (oligodendrocytes). This provides a direct mechanism for the anti-EBV immune response to cause autoimmune damage in the central nervous system.
1:20:53 A "Perfect Storm" of Factors: Developing MS is not as simple as just getting EBV. It requires a combination of factors: the EBV infection itself, a specific genetic predisposition (certain HLA types that present the viral protein in a particular way), and the unlucky generation of these cross-reactive B cells.
1:26:36 Future Implications: These combined findings are a major breakthrough, suggesting that most cases of MS could be prevented. The hosts discuss the profound possibility of developing an EBV vaccine that could stop MS before it ever starts. Other potential interventions include antivirals or therapies designed to block the cross-reactive antibodies.
Summary of Provided Links:
ABRCMS ePoster Spring Symposium for Emerging Scientists: This link leads to information about a virtual poster symposium for high school, community college, and first-year undergraduate students in science.
ASV Annual Meeting Registration (ASV): This is a link to the registration page for the American Society for Virology (ASV) 2022 annual meeting, with deadlines for abstracts and travel grants.
Microbiology & Immunology at LSU Health: This links to the admissions page for the MS and PhD programs in Microbiology and Immunology at Louisiana State University Health in Shreveport.
Viremia in human poliomyelitis (J Exp Med): This is a link to the PubMed entry for the 1954 scientific paper by Dorothy Horstmann discussed in the episode, which first identified poliovirus in the blood (viremia) during early infection.
EBV associated with MS (Science): This links to the Science journal article discussed in the episode, an epidemiological study that found a 32-fold increased risk of developing multiple sclerosis following Epstein-Barr virus infection.
MS antibodies Bind EBV EBNA1 and GlialCAM (Nature): This is a link to the Nature journal article also discussed, which identifies a mechanism of molecular mimicry where antibodies against the EBV protein EBNA1 cross-react with the human brain protein GlialCAM.
Letters read on TWiV 869: This link leads to the text of letters from listeners that were read and discussed during the episode.
Timestamps by Jolene. Thanks!: This is a credit linking to the Twitter profile of the person who provided the helpful timestamps for the episode.