Researchers have developed a groundbreaking vaccine that generates two types of immunity against the Epstein-Barr virus, a virus that almost all of us carry and which has been found to be a primary cause of diseases like multiple sclerosis and some cancers.
After a landmark study published last year found that the risk of developing multiple sclerosis (MS) increased 32-fold after infection with Epstein-Barr virus (EBV), researchers from QIMR Berghofer Medical Research Institute set about developing a vaccine against the virus.
A member of the herpes family of viruses, EBV is carried by about 95% of the population. Most are infected during childhood, after which time the virus lays dormant. But infection in adolescence or early adulthood can cause infectious mononucleosis, “mono” or glandular fever, which is considered a major risk factor in developing EBV-related diseases, including MS. In addition, EBV has been associated with multiple types of lymphoma and nasopharyngeal (nose and throat) cancer.
While preexisting antibodies produced by B cells are known to provide a defense against acute viral infection (humoral immunity), research has shown that effective long-term control depends on the cellular immunity provided by so-called killer T cells, which are responsible for destroying virus-infected cells. So, the researchers designed a vaccine that targets both arms of the immune system.
“Other vaccine efforts have focused on inducing neutralizing antibodies against the virus, which blocks infection of immune B cells during primary acute infection,” said Rajiv Khanna, corresponding author of the study. “But EBV in its latent state hides inside B cells, turning them into tiny virus factories ready to divide and spread whenever our immune defenses are down. It is our killer T cells that detect and control these infected B cells.”
Testing their vaccine by injecting it into the lymph nodes of mice, where the immune response is initiated, the researchers found it produced potent humoral and cellular immunity during primary and latent infection with EBV that was sustained for over seven months. The immune response produced by the vaccine also eliminated or significantly delayed the growth of EBV-positive lymphoma tumor cells in lab models.
The researchers say their vaccine shows promise as a means of providing immunity against EBV and, therefore, the diseases it can lead to.
“Our vaccine formulation induces that killer T cell immune response as well as the neutralizing antibody immune response,” said Khanna. “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.”
In addition to treating the cause of MS, the vaccine could potentially be used to prevent EBV-related cancers and to treat immunocompromised organ transplant recipients for whom EBV infection can be life-threatening.
“QIMR Berghofer has been researching the role of EBV in disease and cancer for decades,” said the study’s lead author Vijayendra Dasari. “It is a really proud moment for us to see all of this work coming together, with this vaccine now heading towards the next important stages of development.”
Those next stages include human trials.
The study was published in the journal Nature Communications and the below video, produced by QIMR Berghofer, explains what EBV is and how the vaccine works.
Source: QIMR Berghofer
