Infection
Epstein-Barr virus: New vaccine may reduce risk of MS, various cancers
Aug
- Researchers developed a vaccine for the Epstein-Barr virus (EBV), which is linked to a 32-fold higher risk of multiple sclerosis (MS).
- They found that the vaccine induced a strong immune against EBV that lasted seven months in mice.
- Further tests are needed to know how these findings may apply to humans.
A groundbreaking new vaccine for the Epstein-Barr virus may pave the way for better preventive and treatment options for conditions such as multiple sclerosis and various cancers.
The Epstein-Barr virus (EBV) is a member of the herpes family of viruses. Around 95% of the world’s adult population is thought to carry the virus.
It is usually contracted during childhood and lays dormant in B cells over the lifespan. B cells are immune cells key for producing antibody responses to other infections.
EBV is usually transmitted through saliva. Soon after contracting it, patients are typically asymptomatic or mildly symptomatic. While most are unaffected by the virus, it develops into symptomatic infectious mononucleosis (IM), also known as glandular fever, in some patients.
IM is a major risk factor for EBV-related conditions such as multiple sclerosis (MS) and Hodgkin lymphoma. Highlighting this risk, a recent study found that, compared to other viruses, those who had contracted EBV were 32 times more likely to develop MS.
EBV is also linked to lymphoid and epithelial cancers, with around 1.5% of all human cancer cases worldwide being linked to the virus.
There are currently no medical interventions available for EBV. Developing such interventions could reduce rates of EBV-related conditions, including MS, Hodgkin lymphoma, and various cancers.
Recently, researchers developed a vaccine that can generate immunity against EBV in mice for seven months.
“The study offers a potential mechanism to address EBV reactivation which could offer hope in illnesses where this is thought could be part of the disease process,” Dr. Thomas Gut, Associate Chair of Medicine at Staten Island University Hospital, who was not involved in the study, told Medical News Today.
The study was published in Nature.
Creating a vaccine for the Epstein-Barr virus has historically been challenging as it changes over its life cycle. Moreover, as the virus itself can lead to the development of tumors, incorporating whole sections of its viral proteins into vaccines could increase cancer risk.
To overcome these issues, researchers incorporated 20 epitopes—small amino acid sequences that activate an immune response—into their vaccine formula. Each epitope targets one of the proteins expressed by EBV at different stages of its life cycle.
The researchers also designed a novel adjuvant to accompany the vaccine to increase its efficacy.
To see how the vaccine works, they tested it in mice genetically altered to have a human-like immune system. The mice included those that had just contracted the virus and those that had contracted it previously and thus had it latent in their B cells.
Ultimately, they found that the vaccine produced a strong immune response in both groups of mice for seven months. This meant that the vaccine helped induce neutralizing antibodies to stop the virus from entering B cells and induce a killer T cell immune response that could destroy infected B cells.
Dr. Howard Pratt, psychiatrist and Board-Certified Medical Director at Community Health of South Florida, Inc. (CHI), not involved in the study, told MNT:
“B cells are typically the primary first line of defense against acute viral infection and most vaccines are focused on these cells. Now, this vaccine is different in that it [also] focused on T cells, which are responsible for killing infected cells and ensuring we have long-standing immunity.”
Dr. Rajiv Khanna, Professor of Tumor Immunology at the QIMR Berghofer Medical Research Institute in Brisbane, Australia, corresponding author of the study, said in a press release:
“Our vaccine formulation induces that killer T cell immune response as well as the neutralizing antibody immune response.
We think that in susceptible individuals, EBV-infected B cells travel to the brain and cause inflammation and damage. If we can prevent this at an early stage of infection then the infected B cells can’t go on to cause the development of secondary disease like MS.”
Dr. Pratt said: “This study was limited to injecting the EVB vaccine into the lymph nodes of mice. Until we see trials on people, we won’t have a better understanding of its efficacy for us.”
Dr. Dana Hawkinson, Medical Director of Infection, Prevention & Control at The University of Kansas Health System, not involved in the study, told MNT that the long-term efficacy of the vaccine for protecting against EBV-associated conditions also remains unknown.
“In addition, we should remember that vaccines do not protect against infection- they protect against disease and severity of disease if one [contracts] pathogen. So the important point for this vaccine is that by inducing strong B- and T-cell immunity, it may protect from possible EBV-associated diseases, like specific cancers, as that person gets older,” he added.
When asked about the study’s implications, Dr. Hawkinson said: “This study is a possible early look into creating a new vaccine that may help reduce diseases caused by EBV after infection, even years or decades after infection.”
Dr. Pratt agreed that the vaccine holds the potential to prevent EBV-related conditions. He added that if the vaccine is effective in humans, it could be a ‘significant breakthrough’ for MS, given the strong link between EBV and MS incidence.
“What is also exciting, is that given that EVB is linked to many other diseases, if proven to be effective, the vaccine could help with more than just MS. It could, for example, reduce certain cancers as well as several other diseases associated with EBV,” he concluded.
