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Why Only Some People Get Seriously Ill from Epstein-Barr Virus: Understanding the Infection’s Impact

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Epstein-Barr Virus

Epstein-Barr Virus: A Common Infection with Serious Implications

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Approximately 10% of individuals carry genetic mutations that heighten their susceptibility to the Epstein-Barr virus (EBV), a common pathogen linked to diseases like multiple sclerosis and lupus. Insights from a study involving over 700,000 participants may clarify why EBV results in severe illness for some, yet remains relatively harmless for the majority.

“Nearly everyone has encountered EBV,” explains Chris Whincup from King’s College London, who did not partake in the research. “How is it that, despite widespread exposure, only a fraction of the population develops autoimmune conditions?” This research offers plausible answers.

The Epstein-Barr virus was initially identified in 1964 when scientists detected its particles in Burkitt’s lymphoma, a type of cancer. Today, over 90% of the population has been infected with EBV, evidenced by the presence of antibodies against the virus.

Initially, EBV is responsible for infectious mononucleosis, often referred to as monofever or glandular fever, which typically resolves in a few weeks. However, it is also linked to chronic autoimmune disorders, as evidenced by a 2022 study demonstrating its role in the onset of multiple sclerosis, leading to nerve damage.

“Why do individuals exhibit such varied responses to the same viral infection?” questions Caleb Lareau at Memorial Sloan Kettering Cancer Center.

To investigate, Lareau and her research team analyzed health data from over 735,000 individuals participating in the British Biobank study and a U.S. cohort called All of Us. Their genomes were sequenced using blood samples. “When EBV infects certain cells, it leaves behind copies in the blood,” shares Lareau, indicating that the human genome in their sample includes EBV genome copies.

The research highlights substantial variability in EBV DNA levels among subjects. Of the participants, 47,452 (9.7%) exhibited over 1.2 complete EBV genomes per 10,000 cells, indicating that while many cleared the virus post-infection, this subset did not.

To comprehend the heightened vulnerability of these individuals, the research team sought specific genomic differences that correlated with high EBV levels. As noted by Ryan Dhindsa from Baylor College of Medicine, they identified 22 genomic regions linked to elevated EBV levels, many of which are previously associated with immune-mediated diseases.

The strongest correlation was found in genes related to the major histocompatibility complex, essential immune proteins in distinguishing between self and foreign cells. “Certain individuals possess mutations in their major histocompatibility complex,” Dhindsa explains. Further studies indicated that these variants may impede the immune system’s capacity to detect EBV infections.

“This virus profoundly impacts our immune system, having lasting effects on certain individuals,” comments Ruth Dobson at Queen Mary University of London. Persistent EBV DNA can subtly stimulate the immune system, potentially leading to autoimmune attacks on the body.

Moreover, the genetic variants linked to high EBV levels were associated with various traits and symptoms, notably an elevated risk for autoimmune diseases such as rheumatoid arthritis and lupus, reinforcing the hypothesis of the virus’s involvement in these conditions.

The research team also identified a connection between these mutations and chronic fatigue, intriguing given that some studies have posited EBV as a contributing factor to myalgic encephalomyelitis, commonly known as chronic fatigue syndrome (ME/CFS). Due to the large sample size, “we can assert that this signal exists,” Dhindsa remarked, although the precise relationship remains unclear.

For Wincup, the primary takeaway is the identification of immune system components damaged by continuous EBV presence. Targeting these components could lead to more effective treatments for EBV-related conditions.

Additionally, vaccination against EBV is a potential avenue. Currently, only experimental vaccines exist. Wincup emphasizes that developing a vaccine would be a significant advancement, arguing that despite its common perception as benign, EBV causes considerable suffering for many. “How benign is it really?”

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Source: www.newscientist.com

Deadly Fungus Causes Ill Frogs to Leap Great Distances, Possibly in Search of Mates

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Bellow’s alpine tree frogs enhance their jumping ability when infected with a common fungus

Robert Valentich/naturepl.com

The chytrid fungus is a lethal pathogen affecting amphibians amid an ongoing global crisis, capable of wiping out entire populations. Yet, for one endangered frog species in Australia, the infection has led to an unusual positive effect: significantly larger hops.

Verreaux’s alpine tree frog (Litoria Verouki Alpina) is impacted by the chytrid fungus, Batrachochytrium dendrobatidis. Those infected can leap nearly a quarter further than their uninfected counterparts.

“These findings remind us of the incredible resilience of these amphibians and their responses to threats from this daunting pathogen. Remarkably, their bodies can display unexpected adaptations,” says Teagan McMahon from the University of Connecticut in New London, who was not involved in the research.

Alexander Wendt and colleagues at the University of Melbourne, Australia, investigated the impact of Bd infection on the health of alpine tree frogs, using their locomotion as an indicator of physiological health.

In their laboratory study, the researchers separated 60 frogs into groups based on infection status. Wendt and his team assessed how the frogs responded to extreme temperature conditions and measured their jumping distances when gently stimulated.

Remarkably, six weeks after infection, the frogs that had contracted Bd exhibited an increase in jumping distance of nearly 24% compared to uninfected ones. Typically, in other amphibian species, energy reserves are drained as the immune system combats the fungus. The physiological responses to Bd can vary significantly among amphibian species, offering temporary advantages in cases of sublethal infections.

“However, as soon as clinical symptoms emerge, it becomes exceedingly challenging for most species,” Wendt notes.

The immune response of alpine tree frogs does not appear robust enough to hinder their reaction to Bd, suggesting that such enhancements may aid them in locating mates quickly before their condition worsens. Other frog species are also known to amplify their mating calls when infected with Bd.

This short-term bolstering of jumping ability can be advantageous when faced with Bd. “From an evolutionary standpoint, it makes sense,” McMahon adds. “Enhanced mobility may contribute to increased transmission rates and prolong the host’s lifespan.”

The influence of Bd on amphibians is increasingly recognized as being shaped by complex interactions between host biology, the fungus, and the surrounding environment. “All we can do is gather as much information as possible to assist these species in surviving and mitigating the spread of Bd before it reaches a critical point,” Wendt emphasizes.

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  • Animal Behavior/
  • Amphibian

Source: www.newscientist.com

Ill chimpanzees search for different plants with medicinal qualities

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A chimpanzee eating sandpaper nuts in Budongo Forest, Uganda.Fig genus

Elodie Freyman (CC-BY)

Some plants that chimpanzees eat when they are sick or injured have been found to have medicinal properties, providing some of the strongest evidence yet that our close relatives self-medicate.

Although there have been reports for decades of chimpanzees using plants to self-medicate, it's difficult to pinpoint when wild animals get sick and what effect their diet may have.

Elodie Freyman Oxford University researchers tracked wild chimpanzees in Uganda's Budongo Forest, recording when they became ill and what they ate. By analysing feces for signs of intestinal parasites and examining urine samples for elevated levels of immune cells, the researchers identified chimpanzees with obvious wounds or intestinal infections.

An analysis of 53 plant extracts ingested by sick or injured chimpanzees found that 88 percent were effective against bacteria pathogenic to humans, including antibiotic-resistant strains like MRSA, and extracts from all species sampled had anti-inflammatory properties.

This systematic approach has allowed the researchers to identify and characterize more species used by chimpanzees than ever before. Kirsty Graham “It's a very impressive project,” said Robert Cole, a researcher at the University of St. Andrews in the UK who was not involved in the work.

Sick chimpanzees would leave the safety of their group to eat certain plants, often choosing plants that were rarely eaten in that area. The rarity of these events makes self-medicating behavior very difficult to observe, but at the same time, it is one of the strongest pieces of evidence that it is a targeted response to illness.

Chimps are typically hesitant to try unfamiliar foods that might be dangerous, Freiman says, so choosing to eat an unusual plant means they have a special reason to do so: “If they're sick, they're not going to stuff their mouths with things that might make them sicker,” she says.

But this doesn't capture everything that's going on, Graham says, because chimpanzee diets are still very diverse. Over generations, a chimpanzee community may be able to overcome this reluctance to new foods if chimpanzees learn from other animals which plants to eat. Simultaneous direct comparisons of the diets of sick and healthy chimpanzees might reveal whether these are active choices, Graham suggests.

Team Members Fabian Schultz Researchers at the Brandenburg University of Applied Sciences in Germany hope that by identifying active compounds in plant extracts, they might uncover promising drug candidates for humans. “What if we could save human lives by following the example of our animal companions?” he says.

In a report released earlier this year, an orangutan, another great ape, was spotted applying plant leaves directly to a wound in an apparent act of self-medication.

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Source: www.newscientist.com