Kissing Disease Virus Causes Multiple Sclerosis?

Human Herpesvirus 4 owes its common name to two British scientists, Michael Epstein and Yvonne Barr, who discovered it in 1964. It is one of the most common viruses in the human population. Most of us come into contact with the virus completely asymptomatically, but the infection itself lasts for life and may reactivate periodically.

Antibodies to EBV are found in almost all people in developing countries, while in the US they are found in 60-70% of the population.

EBV can cause infectious mononucleosis, formerly known as "kissing disease". It occurs when the first contact with the virus is during or after adolescence. Hence, mononucleosis occurs mainly in developed countries, as in developing countries infection occurs most often before about 18 months of age.

The virus discovered by Epstein and Barr also has oncogenic potential and is responsible for both Burkitt's lymphoma and nasopharyngeal cancer. Scientists also suspect an association of EBV with chronic fatigue and depression syndrome (CEBV).

- The hypothesis that EBV causes MS has been analyzed by our group and other teams for several years, but only now have we found convincing evidence for a cause-and-effect relationship, said Prof. Alberto Ascherio, senior author of the study, the results of which have been published in Science. This is an important finding because it shows that most cases of MS could be prevented by stopping EBV infection. Moreover, targeting EBV could lead to the discovery of a cure for MS.

Establishing a causal relationship between the virus and the disease is difficult as EBV infects approximately 95% of adults, and MS is a relatively rare disease whose symptoms begin approximately 10 years after EBV infection. To determine the relationship between EBV and MS, researchers conducted a study of more than 10 million young adults who were active in the US military and identified 955 people diagnosed with MS while in service.

The team analyzed biennial soldiers' serum samples and the relationship between EBV infection and the onset of MS while on active duty. They found that the risk of developing multiple sclerosis increased 32-fold after infection with EBV, but did not change after infection with other viruses. The level of the light chain of neurofilaments in the serum (a biomarker typical for MS) increased in the subjects only after infection with EBV. This observation cannot be explained by any known risk factor for MS, suggesting EBV as the main cause of the disease.

Prof. Ascherio explains that the delay between EBV infection and the onset of MS may be due in part to the failure to detect symptoms of the disease at its earliest stages, and in part to the evolving relationship between EBV and the host's immune system, which is repeatedly stimulated each time the latent virus reactivates .

"There is currently no way to effectively prevent or treat EBV infection, but the development of a vaccine or targeted antiviral drugs could prevent or cure the disease from developing MS," said Prof. Ascherio.

Source: hsph.harvard.edu