What to know about the relationship between the Epstein-Barr virus and leukemia

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The causes of CLL are still unclear, and a potential link with the EBV is just one avenue of research.

One study from 2015 found strong evidence of an association between the infection and the disease. The research team tested 220 people with newly diagnosed CLL and found that more than 59% had detectable levels of the DNA of the virus in their bloodstreams.

The researchers also found that the participants with higher quantities of EBV DNA had poorer outcomes and shorter overall survival rates.

However, they were quick to note that further research is needed to establish whether the virus is responsible for accelerating CLL progression — or if the infection is just a sign that the person’s immune system is already weakened due to the cancer.

Other studies seem to support the idea that high levels of EBV DNA can be used to predict the outcome of CLL.

Another 2015 study compared blood samples from 115 people who had newly diagnosed but untreated CLL with samples from 40 healthy participants.

They found that people with higher levels of EBV DNA needed medical treatment sooner than those with lower levels. Like the other team, they saw shorter overall survival rates among people with CLL and high levels of the viral DNA.

A further study by the same scientists in 2019 determined that the worse outcomes for people with CLL and the EBV could partially stem from a higher prevalence of specific proteins that increase the growth of the cancer.

High levels of these proteins interfere with the normal cell cycle, preventing cell death. The team found a positive correlation between high levels of these proteins and a high EBV DNA load.

Researchers are also investigating whether the virus transforms CLL into the more aggressive form of this cancer: diffuse large B cell lymphoma.

This is known as Richter syndrome, and it occurs in 2–10% of people with CLL. It is still unclear, however, whether EBV infection causes Richter syndrome or whether the syndrome activates the infection.

At the moment, there is no conclusive evidence, and research is ongoing.

A separate 2019 study suggests a possible link between EBV and the development of CLL. The researchers conclude that EBV plays a part in transforming B cells, also known as B lymphocytes.

B lymphocytes are a part of the immune system, and they make antibodies. They develop in bone marrow, and researchers have linked disturbances in the development of these cells with leukemia and other diseases.

In a 2018 study paper, researchers explain that there are two types of EBV, and that these variants behave differently. EBV type 1, they note, transforms B lymphocytes more easily than type 2.

Each study that investigates a possible link between the virus and CLL highlights the importance of further research, particularly into how EBV behaves in healthy people, as past efforts have limited their scope to the effects in people with specific diseases.

This virus is extremely common, and more than 90% of the global population has had the infection. It is also known as human herpesvirus 4. The EBV can cause mononucleosis, also known as glandular fever.

Once a person contracts the infection, the virus stays in their body for life. For the vast majority of people, the virus is latent, or inactive, and the immune system keeps it under control.

Sometimes, however, the virus reactivates, and people with weakened immune systems may experience symptoms of the infection.

Every year, EBV is associated with 200,000 cases of cancer worldwide. As yet, however, there is no way of knowing who will develop these cases.

Currently, health experts know that EBV may increase the risk of developing some types of cancer. However, it is important to remember that very few people with EBV go on to develop cancer.

Cancers associated with EBV include:

• Hodgkin lymphoma
• Burkitt lymphoma
• diffuse large B cell lymphoma
• nasopharyngeal cancers

Research into the link between EBV and cancer, published in 2015, reports that scientists have written more than 20,000 papers about the range of EBV-associated diseases. It, too, stresses the need for further study.

The EBV is an extremely common virus. After the initial infection, it typically remains latent in the body. Researchers are still working to establish whether it plays a role in CLL.

So far, evidence suggests that high levels of the EBV may predict the speed at which the disease progresses. Findings such as this may help doctors identify people who are likely to need treatment sooner than others with CLL.