If you look at Dr Martin Lerner's abortive infection theory of ME/CFS
, he proposes ME/CFS is caused by abortive herpesvirus infections in the tissues. Such infections can be chronic, but they produce no new viral particles, hence there is little virus in the blood — so no virus for PCR to detect. That may be why in ME/CFS antibody titers can be high, but PCR blood tests negative.
Antibody titers measure the immune response to infection, which may be high if there is an ongoing abortive infection in the tissues. I don't think Lerner used PCR; he would always go by antibody titers to detect what he believed were chronic herpesvirus abortive infections in ME/CFS patients.
The non-cytolytic enterovirus infections that Dr Chia thinks causes ME/CFS can also be thought of as a sort of abortive infection, and non-cytolytic infections also do not produce any new viral particles. Thus here also, a blood PCR will often be negative, even when enterovirus antibody titers are high in an ME/CFS patient.
But if you perform PCR on the muscle tissues of ME/CFS patients with chronic enterovirus, then you do get a positive result.
I have heard Dr Chia say that some of the Australian EBV studies on ME/CFS are "bullshit," so I have the impression he is not convinced about ME/CFS due to EBV. I have no idea why. There are several studies showing that around 10% of people get ME/CFS after mononucleosis, which is usually caused by EBV. So that seems quite convincing evidence that EBV can cause ME/CFS. However, I'd like to understand Dr Chia's views on EBV and ME/CFS.
I know that he does not rule out EBV entirely, because in this published letter
by Dr Chia, he finds that EBV is the cause of ME/CFS in 6 out of 200 patients he tested.