You may have never heard of the Epstein-Barr virus. But he knows everything about you.
Most likely, it is living inside of you right now. About 95% of American adults become infected at some point in their lives. And once infected, the virus stays with you.
Most viruses, like the flu, just come and go. A healthy immune system attacks them, kills them, and prevents them from making you sick again. Epstein-Barr and its cousins, including the viruses that cause chickenpox and shingles, can hibernate inside your cells for decades.
This viral family has “evolved with us for millions of years,” said Blossom Damania, a virologist at the University of North Carolina-Chapel Hill. They know all the secrets of your body.
Although childhood Epstein-Barr infections are usually mild, exposure in adolescents and young adults can lead to infectious mononucleosis, a weeks-long illness that affects 125,000 Americans a year and causes sore throats, swollen glands and extreme fatigue. And while Epstein-Barr spends most of her time sleeping, she can wake up again in times of stress or when the immune system is out of whack. Those reactivations are linked to a long list of serious health conditions, including various types of cancer and autoimmune diseases.
Scientists have spent years trying to develop vaccines against Epstein-Barr, or EBV. But recently several advances in medical research have given the search more urgency and more hope of success. In the past year alone, two experimental vaccine efforts made it to human clinical trials.
What has changed?
First, the Epstein-Barr virus has been shown to pose an even greater threat. New research firmly links it to multiple sclerosis, or MS, a potentially disabling chronic disease that affects more than 900,000 Americans and 2.8 million people worldwide.
The journal Science published in January the results of a landmark 20-year study of 10 million military personnel that offers the strongest evidence yet that Epstein-Barr can trigger MS. The new study found that people infected with Epstein-Barr are 32 times more likely to develop MS than uninfected people.
And shedding new light on the mechanisms that might explain that correlation, a separate group of scientists published a study in Nature describing how the virus can cause an autoimmune reaction that leads to MS. The disease, which usually strikes between the ages of 20 and 40, disrupts communication between the brain and other parts of the body and is often characterized by recurrent episodes of extreme fatigue, blurred vision, muscle weakness, and difficulty with balance and coordination. In the worst cases, MS can lead to speech disorders and paralysis.
Amplifying that newfound urgency, several new studies suggest that Epstein-Barr virus reactivation is also involved in some cases of prolonged Covid, a poorly understood condition in which patients experience persistent symptoms that often resemble mononucleosis.
And just as crucial to the push: Pandemic-driven advances in vaccine science, including the mRNA technology used in some Covid vaccines, could accelerate the development of other vaccines, including those against Epstein-Barr, the report said. Dr. Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine. Hotez co-created a low-cost, off-patent covid vaccine called Corbevax.
Some researchers question the need for a vaccine to target a disease like MS that, while debilitating, remains relatively rare.
Eliminating Epstein-Barr would require vaccinating all healthy children even if their risk of developing cancer or multiple sclerosis is small, said Dr. Ralph Horwitz, a professor at Temple University’s Lewis Katz School of Medicine.
Before exposing children to the potential risks of a new vaccine, he said, scientists need to answer basic questions about MS. For example, why would a virus that affects almost everyone cause disease in a small fraction? And what role do stress and other environmental conditions play in that equation?
The answer seems to be that Epstein-Barr is “necessary but not sufficient” to cause the disease, said immunologist Bruce Bebo, executive vice president for research at the National MS Society, adding that the virus “may be the first in a series of dominoes”. .”
Hotez said that researchers could continue to investigate the mysteries surrounding Epstein-Barr and MS even as vaccine efforts continue. Further study is needed to understand which populations might benefit most from a vaccine, and once again it is known, Hotez said, that such a vaccine could potentially be used in patients who are most at risk, such as organ transplant recipients, rather than to be administered universally. to all young people.
“Now that we know that Epstein-Barr is closely related to MS, we could save many lives if we develop the vaccine now,” Damania said, “instead of waiting 10 years” until all the questions are answered.
Moderna and the National Institute of Allergy and Infectious Diseases launched separate clinical trials of the Epstein-Barr vaccines over the past year. The Epstein-Barr vaccines are also in the early stages of testing at Opko Health, a Miami-based biotech company; the Fred Hutchinson Cancer Center in Seattle; and California’s City of Hope National Medical Center.
Scientists have tried to develop Epstein-Barr vaccines for decades only to be thwarted by the complexities of the virus. Epstein-Barr “is a master at evading the immune system,” said Dr. Jessica Durkee-Shock, a clinical immunologist and principal investigator of the NIAID trial.
Both MS and Epstein-Barr-related cancers develop many years after people are infected. So a trial designed to see if a vaccine can prevent these diseases would take decades and a lot of money.
Moderna researchers are initially focused on an easier-to-measure goal: prevention of mononucleosis, which doubles the risk of multiple sclerosis. Mono develops just a month after people are infected with Epstein-Barr, so scientists won’t have to wait that long for results.
Mono can be incredibly disruptive on his own, keeping students out of class and military recruits out of training for weeks. In about 10% of cases, the crippling fatigue lasts six months or more. In 1% of cases, patients develop complications, such as hepatitis and neurological problems.
For now, clinical trials for the Epstein-Barr vaccines are enrolling only adults. “In the future, the perfect vaccine would be given to a young child,” Durkee-Shock said. “And it would protect them throughout their lives and prevent them from getting mononucleosis or any other complications of the Epstein-Barr virus.”
The NIAID vaccine, which is being tested for safety in 40 volunteers, is based on ferritin, an iron storage protein that can be manipulated to display a key viral protein for the immune system. Like a cartoon Transformer, the ferritin nanoparticle self-assembles into what looks like a “little iron soccer ball,” Durkee-Shock said. “This approach, in which many copies of the EBV protein are displayed in a single particle, has been successful for other vaccines, including the HPV and hepatitis B vaccine.”
Moderna’s experimental vaccine, which is being tested on about 270 people, works more like the company’s covid vaccine. Both deliver bits of a virus’s genetic information in molecules called mRNA inside a lipid nanoparticle, or tiny bubble of fat. Moderna, which has dozens of mRNA vaccines in development, hopes to learn from each one and apply those lessons to Epstein-Barr, said Sumana Chandramouli, senior director and lead of the infectious disease research program at Moderna.
“What the covid vaccine has shown us is that mRNA technology is well tolerated, very safe and highly effective,” Chandramouli said.
But mRNA vaccines have limitations.
Although they have saved millions of lives during the covid pandemic, the levels of antibodies generated in response to mRNA vaccines decline after a few months. It is possible that this rapid loss of antibodies is related specifically to the coronavirus and its rapidly evolving new strains, Hotez said. But if decreased immunity is inherent in mRNA technology, that could seriously limit future vaccines.
Designing vaccines against Epstein-Barr is also more complicated than for covid. Epstein-Barr virus and other herpesviruses are comparatively huge, four to five times larger than SARS-CoV-2, the coronavirus that causes covid. And while the coronavirus uses just one protein to infect human cells, the Epstein-Barr virus uses many, four of which are included in the Moderna vaccine.
Earlier experimental Epstein-Barr vaccines targeting a viral protein reduced the rate of infectious mononucleosis but failed to prevent viral infection. Targeting multiple viral proteins may be more effective at preventing infection, said Damania, a UNC virologist.
“If you close one door, the other door is still open,” Damania said. “You have to block infection in all cell types to have a successful vaccine that prevents future infections.”
Source: news.google.com