A Long History
Although altered EBV-specific antibody titers have been repeatedly demonstrated in CFS, no clear evidence for chronic EBV replication has been obtained so far. Authors
Perhaps the most common viral trigger for chronic fatigue syndrome (infectious mononucleosis, aka glandular fever) or Epstein Barr Virus (EBV) is a herpesvirus almost all adults have been exposed to and carry, usually in latent form in their cells.
EBV infection was proposed as the cause of chronic fatigue syndrome not long after the disorder became prominent in the 1980s, but inconsistent study results in the 1980s and 1990s followed by Straus’s 2000 paper (which suggested the search for herpesvirus infections in ME/CFS was over) put a damper on EBV research efforts.
From 2000 to the present only Dr. Lerner with his stream of positive studies (but sometimes challenging study designs) and Dr. Glaser published fairly consistently on EBV in ME/CFS. Recently Dr. Lipkin stated (unpublished) he found no evidence of active EBV infection using high throughput sequencing in the plasma of hundreds of ME/CFS patients.
Despite study inconsistencies, EBV has remained a pathogen of interest in ME/CFS. Both Lerner and Glaser have produced evidence suggesting that a defective form of the EBV virus may be causing the symptoms in some people with ME/CFS. Recent studies suggesting that EBV triggers autoimmune disorders are intriguing given the successful ME/CFS Rituximab treatment trials.
EBV’s ability to reactivate during stress and in hypoxic conditions may have implications for its possible role in ME/CFS as well. A recent laboratory study suggesting that high rates of oxidative stress can reactivate EBV and that antioxidants (including NAC, catalase, and L-glutathione) might be helpful in reducing EBV reactivation is intriguing given the high rates of oxidative stress found in ME/CFS.
Now, in a surprising turn, German researchers have not only put the spotlight back on EBV, but have dug deeper into EBV, ME/CFS, and the associated immune response than any group has before.
- Deficient EBV-specific B- and T-cell response in patients with chronic fatigue syndrome. Loebel M, Strohschein K, Giannini C, Koelsch U, Bauer S, Doebis C, Thomas S, Unterwalder N, von Baehr V, Reinke P, Knops M, Hanitsch LG, Meisel C, Volk HD, Scheibenbogen C. PLoS One. 2014 Jan 15;9(1):e85387. doi: 10.1371/journal.pone.0085387. eCollection 2014.
“Taken together, our study provides clear evidence that deficiency of EBV-specific immune response is present in CFS” The authors
The adaptive part of the immune system, the one that takes time to kick in, comes in the form of B-cell produced antibodies that lock onto proteins the virus produces and cytotoxic T-cells that attempt to the kill the virus. (B-cell’s attack the virus in the blood and cytotoxic T-cell attack virally infected cells.)
Noting some unusual findings in their lab, these researchers looked at these antibodies and T-cells to see if people with chronic fatigue syndrome were mounting an effective immune response against EBV. They also looked for direct evidence of an active EBV infection.
EBV replication occurs when the virus produces proteins in a sequence that allows it to build another virus. One theory, developed by Dr. Lerner and a group at The Ohio State University (that includes Drs. Ariza, Glaser, and Williams), proposes that EBV undergoes ‘abortive replication’ in some people with ME/CFS. In abortive replication, a defective form of EBV produces early proteins, but is unable to produce later ones. The Ohio State group believes continual production of these proteins is causing a chronic inflammatory state in some people with ME/CFS.
First, the German researchers found evidence of primary EBV infection or reactivation (increased IgM antibodies to a late EBV protein in @15% of patients vs 3% of controls) in significantly more ME/CFS patients than controls. The fact that this could be a ‘primary infection’; i.e. it represents the first time these patients are exposed to the virus is intriguing. A primary infection of EBV early in life usually leads to nothing more than a cold; a primary infection later in life can have serious consequences including infectious mononucleosis.
Having found evidence that an active EBV infection was more common in people with ME/CFS than controls, they looked to see if a reduced immune response was responsible for that.
The first hint of a reduced immune response to EBV in ME/CFS came in the form of a lack of antibodies to EBV-produced proteins VCA and EBNA1.
But first, a short antibody primer:
- IgG antibodies are ‘memory antibodies’ that travel through our system looking for evidence that a pathogen is present. Once your B-cells have mounted an attack against a pathogen, they are always present in our system. Therefore, IgG antibodies are not evidence of an ongoing infection.
- IgM antibodies are attack proteins associated with a pathogen. High IgM titers to a viral protein generally reflect a primary infection.
With two types of antibodies being manufactured against a range of viral proteins the situation becomes complicated, but a healthy immune system should produce an array of both IgG and IgM antibodies that can detect (IgG) and inhibit (IgM) pathogens (found outside cells) at different stages of their lifecycles.
As they dug deeper, the German researchers found holes in the immune response to EBV in ME/CFS patients.
Immune Holes to Epstein-Barr Virus Found
Immune Hole #1 – reduced antibody response
Evidence of a impaired B-cell response to EBV first came in the form of missing IgG antibodies to VCA and EBNA in 13% of ME/CFS patients compared to 4% of controls. This indicated that 13% of their ME/CFS study population did not have some of the memory B-cells needed to detect an EBV infection.
Increased IgM antibody responses in ME/CFS (17.5% in ME/CFS vs 4% in controls), on the other hand, suggested active and perhaps primary EBV infections were more commonly found in ME/CFS patients.
All told, 30% of the ME/CFS patients either had reduced IgG (EBNA-IgG) or increased IgM (VCA) responses to EBV.
That finding prompted a deeper look, and a much larger study that found no IgG response to a protein expressed during latency by EBV (called EBNA-1 protein) in 10% of IgG positive ME/CS patients. This indicated that the immune systems of approximately 10% of the ME/CFS group were unable to detect a very early stage of EBV latency.
Latency – For EBV to maintain itself in the body over time, it needs to be able to maintain itself in B-cells in a process called latency. EBNA-1 is a protein that helps maintain EBV’s viral genome in the earliest stages of latency.
The authors noted that people with severe infectious mononucleosis and chronic active Epstein-Barr virus disease have similar findings (although it’s not clear why, given that EBNA-1 is not involved, so far as we know, in replication).
That brings up the question of how many people with ME/CFS would have fit into the category of severe mononucleosis at the time they got ill. The Dubbo studies found that more severe infections greatly increase the risk of coming down with ME/CFS.
Immune Hole #2 – reduced frequencies of two B-cell antibody producing cells
Intrigued by the findings, the German researchers dug deeper into the immune response to EBV. They took blood (PBMCs) from ME/CFS patients and then stimulated it with CpG, SAC, and PWM for seven days, and found reduced frequencies of B-cells producing antibodies against VCA and EBNA-1, and for the first time they found evidence of immune deficiencies in most people with ME/CFS.
No less than 59% of ME/CFS samples had a diminished response to a later stage EBV protein (VCA) produced during the late stage of lytic replication, and a whopping 76% of ME/CFS samples had a diminished response to the EBNA-1 protein. With the VCA finding we have evidence suggesting many people with ME/CFS may have trouble controlling EBV replication.
Calling the findings ‘remarkable’, the authors suggested that either the memory B-cells associated with these EBV antigens had been lost or had failed to develop into antibody-secreting cells.
Immune Hole #3 – Reduced T-cell response to EBNA-1
A similar deficiency in the T-cell response to EBNA-1 indicated that both arms of the adaptive immune response to Epstein-Barr Virus, the B-cells and the T-cells, had difficult recognizing and responding to this protein.
Citing other disorders such as HIV, they suggested that persistent EBV reactivation in ME/CFS had driven the T-cell response in ME/CFS into ‘exhaustion’. (A similar suggestion has been made with regard to natural killer cells that attack pathogens early in an infection, which use killing methods similar to those employed by T-cells.)
Further analysis suggested that T-cell suppressor cells which decrease B-cell responses were not responsible for the B-cell suppression found. Normal B-cell responses to herpes simplex and cytomegalovirus suggested that the deficient B-cell responses were associated with EBV and not other herpesviruses.
Immune Hole #4 – reduced T-cell response to EBNA-1, reduced T-cell responses to EBV
Next they explored T-cell induced cytokine production. The T-cells should produce an array of cytokines against EBV. About 20% fewer ME/CFS patients (70% of controls vs 50% of ME/CFS patients) were able to mount an IFN-y response against EBV.
Looking specifically at the latency associated EBNA-I protein, they found the startling result that no ME/CFS patients mounted an IFN-y response against it.
They also found that ME/CFS patients produced significantly lower amounts of the pro-inflammatory cytokine TNF-a in response to EBV. Finally, a lower percentage of patients produced IL-2 as well. The reduced cytokine production suggested cytotoxic T-cells, one of the big guns of the adaptive immune response, were not being strongly activated in response to EBV.
Immune Hole #5 – Reduced frequencies of EBNA-1 specific T-cells
The researchers dug deeper still. Next they stimulated the blood (PBMCs) of ME/CFS patients and healthy controls (n=40) with the EBNA-1 protein, expanded the cells in the presence of IL-2 and Il-7, and then checked the T-cell response to them. Specific types of T-cells should be produced to attack EBV, but reduced frequencies of EBV-specific T-cells occurred in about 50% of the ME/CFS samples. That again suggested the cytotoxic T-cell response to the EBNA-1 protein was substantially reduced in ME/CFS.
Direct Evidence of Active EBV Infection
“Remarkably, in line with this finding we could provide evidence of enhanced viral load of EBV by detection of EBV DNA in a significantly higher proportion of patients compared to healthy controls.” The authors
Using a real-time PCR test in the whole blood that looked for ‘low-copy’ numbers (<1,000-2930 copies/ml) they found evidence of increased EBV viral load in 7.2% of 290 ME/CFS patients. When they dug deeper and did the same test in PBMCs in a subset of patients, they found that a whopping 55% of patients (vs 13% of controls) tested positive for EBV.
The viral loads were far below those found in other EBV associated illnesses such as infectious mononucleosis or post-transplant EBV infections, and there was no evidence of lytic replication (i.e., full replication of the virus), but something the authors called ‘latency-associated replication’ was common in people with ME/CFS, yet not in healthy controls.
The Lipkin Study
Using PCR the German researchers found much higher rates of EBV infection in PBMCs vs whole blood and no evidence of EBV infection in plasma.
Neither the Lipkin CFI ME/CFS pathogen study nor the CFIDS Association of America BSR study found evidence of EBV infection in ME/CFS. According to Russell Fleming’s transcript of the Lipkin talk, the CFI study looked in the plasma of both the Montoya and the ME/CFS experts’ samples.
Whole blood contains plasma, red blood cells, white blood cells, and platelets. Plasma makes up 55% of blood volume and contains water (90%), proteins, nutrients, waste products, clotting factors, hormones and carbon dioxide. It does not contain red or white blood cells or thrombocytes.
EBV DNA has certainly been found successfully in plasma before and plasma has been used to track EBV activation. Serum/plasma EBV PCR kits are available for purchase. Researchers search and find EBV in plasma frequently.
Dr. Chia, however, reportedly stated he believes the use of plasma rather than blood was a serious mistake, and the Germans were able to find evidence of EBV activation in blood but not in plasma.
The German researchers are deepening their study of EBV and ME/CFS and currently evaluating antibody responses against a broader variety of EBV peptides derived from 8 different proteins. They are also quantifying the levels of memory B-cells targeting EBNA-1 and VCA.
“We think the altered pattern of the specific immune response to EBV may be suitable as a diagnostic marker for CFS.” Authors
It was if these researchers kept pulling a string that got longer and longer. First their interest was piqued by some paradoxical antibody findings, then they found widespread deficiencies in some antibody responses and T-cell responses, and finally they saw evidence of an active EBV infection in the blood of 55% people with ME/CFS (vs 7% of controls).
Much is still unclear. The EBNA-1 protein that the immune systems of ME/CFS patients had trouble responding to is associated with ‘early latency’, not EBV replication. The authors’ reference to ‘latency associated replication’ is unclear given that latency is not usually associated with replication. When asked what importance their findings have for EBV reactivation or EBV survival or more severe casesof infectious mononucleosis in ME/CFS, the authors stated they can’t answer those questions yet.
Some researchers believe, however, that reduced cytotoxic T-cell responses to EBV increase the risk for autoimmune disorders. (We’ll be covering that possibility in the next blog.) These findings also suggest that the proposal by Lerner and the OSU group of Drs. Ariza, Glazer, and Williams that an abortive lytic process (smoldering EBV infection) is present in many people with ME/CFS may be correct.
While it will take more work to determine what these findings mean for ME/CFS, the broad range of dysfunction found and the high rate of active EBV infection (in plasma) would appear to put this pathogen back into play in a meaningful way in ME/CFS.