Notes on Viral Testing in ME/CFS
There are a number of complexities and pitfalls involved in ME/CFS viral testing, which these notes cover.
The viruses linked to ME/CFS. The main viruses linked to ME/CFS are enteroviruses (coxsackievirus B and echovirus), herpesviruses (Epstein-Barr virus, HHV-6, cytomegalovirus, varicella zoster virus), and parvovirus B19. And the bacterium Chlamydia pneumoniae is also associated with ME/CFS.
PCR blood tests for enterovirus and herpesvirus are generally not useful in ME/CFS. PCR directly detects the presence of a pathogen in the sample tested (eg, in a blood sample or tissue sample). However, PCR blood tests for viruses typically come out as negative in ME/CFS.
This may be explained by the fact that ME/CFS has been linked to non-cytolytic enterovirus infections of the muscles, intestines and brain, to partial reactivation of HHV-6, and is theorized might be caused by abortive herpesvirus infections. But all of these are intracellular infections which remain inside human cells, and do not produce many new viral particles. So you will have very few viral particles in the blood, thus explaining why PCR is often negative in ME/CFS.
In the case of ME/CFS involving chronic active enterovirus infection, Dr John Chia found that even with the most sensitive PCR blood tests, enterovirus was only detected around 30% of the time (although interestingly, in severe bedbound patients it was detected 70% of the time, but in milder patients only 12% of the time).1 So blood PCR is not a reliable method.
The exception is ME/CFS linked to parvovirus B19, where the virus can be found in the blood, so blood PCR is useful in parvovirus ME/CFS.
So generally ME/CFS specialist doctors will use antibody blood tests, rather than PCR. Antibody tests measure the immune response to a pathogen, in contrast to PCR which detects the pathogen itself. The advantage of antibody tests is that even if the pathogen is hiding in the tissues as an intracellular infection, if the infection is extensive enough, tests may detect an elevated antibody response to that infection.
Viral antibody blood tests are generally used in ME/CFS, but test results are interpreted in a different way to normal. Antibodies come in different types, with IgM and IgG antibodies being the main players in fighting infections. When you first catch a pathogen, within days of the acute infection starting, IgM antibodies that target that pathogen are created by the immune system as part of the immune response.
As the infection is brought under control by the immune system, and the infection is either completely eliminated from the body or has been reduced to an inactive state (where the pathogen is hiding in a latent state inside cells), levels of IgM go down to zero, and at the same time, IgG antibodies start being produced which target that particular pathogen.
These IgG antibodies remain mildly raised for life, providing lifelong protection against reinfection with that particular pathogen. And for viruses which cannot be fully eliminated from the the body and hide in cells, this mildly elevated IgG helps stop the virus from reactivating (while the virus remains in a dormant latent state in cells, it does not produce any new viral particles).
Thus in a blood test, finding high IgM and low IgG antibody levels indicates a new acute infection. Finding low IgM and mildly raised IgG indicates a past infection that has been brought under control. And if both IgM and IgG are raised, this indicates a past infection that has reactivated from latency.
So these are the normal general rules used by infectious disease (ID) doctors for interpreting antibody titers, and they are summarized in the follow table.
|Normal Rules for Interpreting Antibody Titers|
|High||Low||A new acute infection that has just been caught.|
|Low||Mildly Raised||A probable past infection, either inactive (in a latent state) or completely eliminated from the body and cured.|
|High||High||A previous infection that has reactivated from a latent state.|
High IgM indicates a normal active infection as we normally understand them: an infection that is producing lots of new viral particles, either as an initial acute infection, or as a flare up and reactivation of an old infection. Such infections with high IgM typically show up positive if you test the blood for the presence of the actual virus by PCR.
In the case of ME/CFS and chronic Lyme disease, however, IgM is typically low, but IgG titers are usually substantially raised (not just mildly raised) on a long-term basis.
To an ID specialist, finding low IgM and chronically high IgG is curious, but they do not see it as an active infection (especially because blood PCR tests are usually negative, as you do not get much virus in the blood in ME/CFS).
But to an ME/CFS specialist, low IgM with chronically high IgG signifies there may be ongoing active infection in the tissues — not a normal active infection which produces lots of viral particles, but a chronic active infection in the form of a non-cytolytic enterovirus infection, an abortive herpesvirus infection, or a partial reactivation of a virus.
So in this way, ME/CFS specialists interpret antibody blood tests differently to ID specialists. Thus if you are an ME/CFS patient and your blood tests indicate low IgM, but with high IgG titers, an ID specialist will tell you that you do not have an active infection. But an ME/CFS specialist will view your high IgG titers as evidence of an ongoing active infection somewhere in the body.
So in summary, ME/CFS specialists use a fourth rule (in addition to the three rules in the table above), which is the following:
|Extra Rule for Interpreting Antibody Titers in ME/CFS|
|Low||High||Chronic low-level active infection in the tissues.|
This fourth rule is a controversial though, as some researchers believe the high IgG titers in ME/CFS are of no significance, and do not believe ME/CFS is caused by ongoing infection. However in the case of enterovirus ME/CFS, there is considerable evidence for chronic active low-level infection in the tissues, which are the likely cause of these chronically high IgG titers.
The threshold IgG titer for diagnosing a chronic active infection. So we have established that ME/CFS specialists view persistently high IgG titers as evidence for chronic active infection. Thus in order to determine which chronic active viral infections may be underpinning your ME/CFS, you will generally check for high IgG antibody titers in viral antibody tests.
But what exactly do we mean by high IgG titers? How do we know if the IgG titers on our viral test lab reports are high, or merely mildly raised? What threshold value indicates high IgG, and in turn suggests active infection?
The typical laboratory report usually does not tell you if your titers are high. The reference range on the lab report only relates to whether antibodies are absent or present. The lab report will specify a certain reference value for a negative result — for example the lab report may say: negative < 3.0 U/ml — and if your antibody titers are below that value, then you do not have those antibodies present in the blood. So this reference value only tell you if antibodies are absent or present; it does not indicate if your antibody titers are high.
Usually the experience and expertise of an ME/CFS specialist doctor will enable them to diagnose high IgG titers. Some ME/CFS doctors like Dr Chia have performed in-house studies to properly calibrate the threshold for high IgG titers, and have publicized the threshold value. But other ME/CFS doctors have not publicized the threshold values they use.
The proper method for calibrating the threshold for high IgG involves measuring the titers in a group of ME/CFS patients, and also in a group of healthy people, and comparing the average IgG titers for each of these two groups. The ME/CFS patients' average titers will be high, and the healthy peoples' average titers will be substantially lower. You then set the threshold value for high IgG titers somewhere between these two averages. Dr John Chia used precisely this method to determine the threshold for high titers in the coxsackievirus B and echovirus ARUP Lab tests (see this video at 10:34).
Alternatively some doctors like Dr Daniel Dantini set the threshold value for high IgG as being 4 times the average IgG titer of the group of healthy people.1 But unless you have information on the average titers in healthy people for a given test (and your lab report will not tell you this), this method is of little help.
So, apart from the coxsackievirus B and echovirus ARUP Lab tests, for all other lab tests we do not have this threshold value rigorously calibrated and made available to ME/CFS patients. Thus for ME/CFS patients who are unable to see an ME/CFS specialist doctor, it is hard to get an accurate diagnosis for high IgG. As patients we can only guess at what constitutes high IgG titers.
However, we can make an educated guess based on Dr Chia's calibration of the ARUP Lab coxsackievirus B and echovirus tests: Dr Chia determined that titers in the region of 1:160 to 1:320 and higher are the threshold for chronic active infection. Now ARUP Lab state that the reference range for negative in these tests is 1:10. So if you divide 160 by 10, you get 16. So here the threshold titer Dr Chia uses for chronic active infection is 16 times higher than the reference titer for negative.
So if we assume we can extrapolate to other tests, we can state an approximate rule: IgG antibody levels are deemed high if they are at least 16 times the reference threshold for negative. However, note that this factor of 16 has not been validated by any ME/CFS specialist doctors, but at least provides something to work with in the absence of guidance from an ME/CFS doctor.
Special note on enterovirus testing in ME/CFS. When testing for the chronic enteroviruses infections (coxsackievirus B and echovirus) found in the tissues of ME/CFS patients, there are some special considerations: Dr John Chia discovered that only the neutralization method of antibody testing, which is the gold standard in terms of sensitivity, is able to detect chronic enterovirus infections in ME/CFS patients. Dr Chia uses the ARUP Lab antibody tests for coxsackievirus B and echovirus, which employ the sensitive micro-neutralization method (details here).
Other methods of antibody testing such as EIA, ELISA, IFA may not be sensitive enough to detect chronic enterovirus. And CFT is definitely not sensitive enough to detect chronic enterovirus infections. Thus for reliable chronic coxsackievirus B and echovirus testing in ME/CFS patients, a neutralization antibody test is required.
For the herpesviruses linked to ME/CFS (EBV, HHV-6 and CMV), the EIA, ELISA or IFA methods of antibody testing are fine, and there is no need to use the neutralization method.
Here are the various methods of antibody testing, in order of highest sensitivity:
- Neutralization test (various types of neutralization test: micro-neutralization test, plaque reduction neutralization test, cytopathic effect neutralization test). Neutralization is the most sensitive test method.
- EIA (enzyme immunoassay) and ELISA (enzyme-linked immunosorbent assay). ELISA is a specific type of EIA. EIA has around the same sensitivity as IFA.
- IFA (immunofluorescence assay), also called IFT (immunofluorescence test) and IF.
- CFT (complement fixation test), also called CF.
Notes on Antiviral Treatment of ME/CFS
Antiviral treatment of ME/CFS involving EBV, HHV-6 or CMV takes a long time. In Dr Martin Lerner's clinical trials using Valtrex or Famvir to treat ME/CFS associated with EBV, and Valcyte to treat ME/CFS where HHV-6 and/or CMV infection are involved, it would take 3.5 months before the first first signs of improvement in symptoms would appear, and around 1 or 2 years for the full benefits if antiviral therapy to manifest.
Why does it take so long to treat ME/CFS associated with these herpesviruses, when under normal circumstances, antivirals are able to bring infections under control in a matter of weeks? The answer may lie in the unusual type of herpesviruses infections Dr Lerner theorized cause ME/CFS, namely abortive herpesvirus infections. A normal productive viral infection produces new viral particles, whereas an abortive infection does not create viral particles, but an abortive infection can nevertheless chronically persist within cells.
Antivirals such as Valtrex and Valcyte do not have any direct antiviral effect against abortive herpesvirus infections, but are efficacious against productive herpesvirus infections. Dr Lerner hypothesized that in ME/CFS there is a low-level productive infection alongside the abortive infection, and that viral particles from the productive infection constantly re-seed the abortive infection, so that the abortive infection cannot be cleared.1
When you take herpesvirus antivirals, they target the productive infection, and so greatly reduce the number of viral particles produced. This stops the abortive infection from being re-seeded, so that eventually the immune system very slowly clears the abortive infection (or at least reduces the abortive infection). This according to Dr Lerner is why antivirals take such a long time to work in ME/CFS linked to EBV, HHV-6 and CMV. This is only a theory, but Lerner's ideas are currently being further researched at Ohio State University.1
The exception to this lengthy treatment time is ME/CFS associated with reactivation of varicella zoster virus (VZV); this form of ME/CFS rapidly responds to antiviral such as Valtrex within a matter of weeks. But the difference is that VZV reactivation is a normal productive infection which produces viral particles, and Valtrex is very effective against productive VZV. It is only abortive infections which Valtrex and Valcyte have no direct effect against.
Antiviral or immunomodulatory treatment of enterovirus takes 2 or 3 months. Treatments such as oxymatrine, Epivir, tenofovir and interferon beta which target the enteroviruses linked to ME/CFS (namely coxsackievirus B or echovirus) take around 2 or 3 months to work. It is the intracellular non-cytolytic form of enterovirus which is found in ME/CFS, and which these treatments target.
Antiviral treatment of varicella zoster virus reactivation takes just a few weeks. Dr John Chia finds around 2% of ME/CFS patients have varicella zoster virus (VZV) reactivation in their dorsal root ganglia as the cause of their ME/CFS. Such a reactivation is indicated by a shingles rash. This VZV form of ME/CFS is a very easily treatable type of ME/CFS. Dr Chia finds all it requires is a short course of acyclovir or Valtrex for just a few weeks.
In this video at 6:58 Dr Chia tells the story of a high flying executive who became bedridden with severe ME/CFS. After 11 months in this bedridden state, Dr Chia noticed two little shingles blisters appearing on this patient, and thus suspected VZV reactivation ME/CFS. Reactivation of VZV is normally diagnosed just by the appeared of shingles blisters, rather than through viral blood tests. Dr Chia gave her some acyclovir to take daily, and within 3 weeks she was back to full-time work. That's how quickly VZV ME/CFS responds to antivirals.