Epstein Barr Virus I: EBV Rides Again? A Laymen's Guide by Cort Johnson
(Oct 09)
EBV was the first major disappointment for CFS
researchers. Several studies in late eighties suggested EBV might be the cause
of CFS but subsequent studies
revealed EBV activation to be no higher in CFS
than controls. In recent years, however, like Lazarus rising from the grave,
EBV’s role in CFS has been given
new life by several research groups that have continued to examined this
intriguing virus in greater detail.
EBV in Chronic Fatigue Syndrome (ME/CFS)
Historical Background - EBV has a long
history in chronic fatigue syndrome (ME/CFS).
The finding of increased antibody levels to EBV in 1985 suggested that a chronic
EBV infection caused ME/CFS. Five
studies between 1985 and 1988 indicating ME/ CFS
patients had increased levels of antibodies to EBV lead to the disease for a
time being ca
lled Chronic Epstein-Barr Virus (and the CFIDS Association of
America being called the Chronic Epstein-Barr Virus Association).
Further studies, however, found that healthy people often had similar
antibody levels and later studies found no evidence of unusual EBV reactivation
in ME/
CFS. The inability of researchers to find EBV
DNA in the throat washings of
CFS patients – a common finding in immunosuppressed subjects
– suggested ME/ CFS
patients were not subject to high levels of EBV reactivation. Importantly no
studies were able to link antibody levels or viral load to symptom severity in
the disease and interest in EBV as a causative agent waned.
Two research groups have maintained interest in EBV, however, and the
recent CDC sponsored Dubbo studies have once again brought it to the fore. There are
at least three ideas regarding EBV and ME/ CFS:
- Rates of active EBV infection are not higher in chronic fatigue syndrome
(ME/CFS) patients than the population at large: EBV infection does not play a
role in this disease.
- EBV infection
during adolescence/adulthood that leads to infectious mononucleosis is a risk
factor for ME/ CFS.
- An ongoing chronic and mostly undetected EBV infection by itself or in
interaction with other viruses causes significant symptoms
in a subset of patients.
Background – The presence of Epstein-Barr Virus (EBV)
in our saliva makes EBV infection common. Indeed EBV, or as it is now called
human herpesvirus 4 (HHV-4), infection is almost ubiquitous.
EBV, which was discovered in 1964, resides in resting (memory) B-cells,
usually for life. Early in the infection EBV turns on genes that
produce new viruses (virions) that go on to infect new cells. By the time the
immune sytem knocks EBV it has usually established itself in the
The Epstein Barr Virus Pages
DNA of B-cells. Except for occassional forays at
reactivation to reestablish itself in new cells once EBV establishes itself in
B-cells it turns its activity levels down enough to run under the immune
system’s radar. Everytime the B-cell duplicates, though, the presence of EBV
DNA in the cells DNA
allows the virus to be duplicated as well. EBV, then, does not need to infect
new cells to remain present in the body for life.
Most people carry a fair constant number of EBV
infected cells in their bodies. The number of infected cells each person carries
can vary enormously, however. People with higher levels of EBV infected cells
are not necessarily less healthy than people with lower levels of cells.
Primary EBV Infection - The consequences of an EBV
infection vary dramatically depending on when it occurs. While a primary
(initial) infection during childhood is usually benign, a primary EBV infection
during adolescence causes infectious mononucleosis in about 30-40 percent of
those infected, and about 10% of those infected come adown with a
post-infectious fatigue syndrome or CFS.
A recent study found that those that encountered EBV later in life - i.e.
came down with infectious mononucleosis – had a higher risk of coming
down with MS than those exposed to it as a child.
EBV, then, is not as benign as was once thought. Sooner or later most
people get exposed to EBV. If you do so as a child you usually have a mild
infection, if you do so as an adolescent or adult you have a good chance of
getting infectious mononucleosis, and if you get infectious mononucleosis you
have a fairly good chance of coming down with post-viral fatigue or chronic
fatigue syndrome, and an increased (but still low) chance of getting MS.
EBV reactivation - A recent paper suggests that the
old paradigm; irregular attempts by EBV to reactivate and infect new cells is
wrong. This paper suggests that EBV is constantly testing the immune system.
This occurs when EBV infected B-cells move into the lymphoid organs (e.g. lymph
nodes, spleen) where they get triggered by antigens (pathogenic particles) to
transform themselves into plasma cells and produce antibodies. During this
transformation EBV uses the B- cells genetic machinery to produce more EBV
virions. This reactivation process is kept in check by EBV spectific cytotoxic
T-cells.
The vast majority of EBV reactivation cases are benign, however, and go
unnoticed. Some degree of EBV reactivation is normal and expected in everyone
carrying the virus. One study found that EBV reactivation was present in about
10% of healthy individuals. Another found a detectable viral load was present in
over a third of healthy individuals and another that about 25% of healthy
individuals had EBV DNA in their
blood (Maurmann et. al. 2003).
EBV reactivation is, however, implicated in several very rare
cancers and may be associated with transplant rejection and multiple sclerosis.
Several situations, including an impaired innate immune response, physical or
psychological stress, organ transplantation and HHV-6 and HIV infection have
been shown to trigger the EBV reactivation.
Dig Deeper! Part II: EBV and chronic fatigue syndrome
The Phoenix Rising website and most of the articles in it are created by a layman. It is not a substitute for a
physician and is for informational uses only.