List of enterovirus infection studies

Enteroviruses such as Coxsackie B virus have long been associated with myalgic encephalomyelitis, with nearly thirty studies finding evidence of chronic enterovirus infection in ME/CFS patients. The enterovirus theory of ME/CFS is the oldest and probably most researched.

Early studies in the 1970s and 1980s focused on the elevated coxsackievirus B antibody titers often found in ME/CFS, which suggested persistent enterovirus infections in these patients, but did not provide direct evidence of the virus. Once molecular testing methods such as PCR became available towards the end of the 1980s, then studies were able to demonstrate direct evidence of enterovirus infection, by detecting enteroviral RNA in the tissues of ME/CFS patients.

The late 1980s also saw the introduction of the 5-D8/1 monoclonal antibody, developed by Professor James Mowbray and his team, for detecting enterovirus VP1 protein in tissue biopsies and in the blood (the antibody binds to VP1 and stains the tissues brown when enterovirus is present). This again provided direct evidence of persistent enterovirus infection.

Throughout the 1990s, using molecular methods such as PCR, a series of British studies detected enterovirus RNA much more frequently in the muscle tissues of ME/CFS patients compared to healthy controls. And one important study by Cunningham et al uncovered the first evidence that the persistent infections found in ME/CFS were due to a mutated enterovirus; this mutated virus is now reasonably well understood and referred to as non-cytolytic enterovirus.

These British findings of enterovirus infection in the tissues of ME/CFS patients were not replicated in the United States until Dr John Chia's 2008 study, which found both enterovirus RNA and enterovirus VP1 protein much more frequently in the stomach tissues of ME/CFS patients compared to controls.

There have been over 30 ME/CFS enterovirus studies in total, and the majority have been positive (finding enterovirus much more commonly in ME/CFS patients than healthy controls); in the list below, positive studies are indicated by a + symbol. However, there were also 4 negative studies (finding no difference between patients and healthy controls) and these are indicated by the − symbol. Note that two of these negative studies had small cohorts of only around 30 patients. Note also that some studies used PCR primers targeting the 5′UTR region of the enteroviral genome — a region known to contain deletions in chronic enterovirus infections; thus these PCR primers may thus not be appropriate for detecting chronic enterovirus, which may explain some negative study results.

Early ME/CFS enterovirus research
This early period of enterovirus research from 1970 to 2003 (comprises mainly British studies).

Dr John Chia's ME/CFS enterovirus research
John Chia in California: his research papers on enterovirus in ME/CFS from 2005 to present.

Other investigations by John Chia
Dr Chia took more than 2500 blood samples from more than 510 ME/CFS patients, and in their peripheral blood lymphocyte (PBL) cells, 35% of these patients tested positive for enterovirus RNA, using a very sensitive test: the Chemicon RT-PCR EAI 3 primer test, with Qiagen 1-step RT-PCR enzyme.

Interestingly, for the more severe bedridden patients, Dr Chia found enterovirus RNA in 70% of the PBL cells. But for the less ill patients, enterovirus RNA was found in only 12%.

The sensitivity of the test was high, around 80 to 800 RNA copies per ml of blood, yet typically the same patient would not always test positive using this test (they would be positive on some occasions and negative on others), so Chia says it is clear that the enteroviral RNA present in the blood in ME/CFS is at very low levels. Dr Chia says any PCR tests which have insufficient sensitivity (above 1000 copies of RNA per ml of blood) will almost always give negative results in ME/CFS patients.

Learn more

 * Dr John Chia, International Symposium on Viruses In CFS 2008, The Role of Enterovirus in ME/CFS
 * Dr John Chia, State of Knowledge Workshop on ME/CFS Research 2011 (Day 1) Part 1
 * Dr John Chia, State of Knowledge Workshop on ME/CFS Research 2011 (Day 1) Part 2


 * Invest in ME International ME Conference, London 2009: Diagnosis and Treatment of ME/CFS Associated With Chronic Enterovirus Infection


 * Invest in ME International ME Conference, London 2010: Enterovirus Infection in ME/CFS


 * Invest in ME International ME Conference, London 2011: Clinical and Research Experience of Enteroviral Involvement in ME/CFS
 * Invest in ME International ME Conference, London 2015: Enteroviruses and ME/CFS: An Update on Pathogenesis
 * Chronic viral infections in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), Enterovirus Section.