I posted the following elsewhere, but it may be worth posting in this thread too:
Very interesting point made at timecode 45:50 in
this talk by Dr Fluge, when a member of the audience asks Dr Fluge if it is possible to rule out the theory that ME/CFS may be driven by an intracellular infection of B-cells, such as an infection with Epstein-Barr virus.
Since rituximab kills the B-cells, this drug would also wipe out any intracellular infection in these cells, and thus in theory, this could explain how, if the B-cell infection were causing ME/CFS, rituximab can cure ME/CFS.
Dr Fluge replies by staying that he cannot entirely rule out such a possibility, but points out that rituximab kills the B-cells within days, so he says that if ME/CFS were directly caused by a B-cell infection, it would be difficult to explain why it takes 7 or 8 months before ME/CFS patients treated with rituximab improve. If ME/CFS were directly caused by a B-cell infection, you would expect the improvements to appear as soon as the B-cells were killed, days after rituximab is given.
Dr Fluge then mentions the case of a patient who was very sick, suffering for years with chronic Epstein-Barr virus infection, including infection of the B-cells (verified by B-cell biopsy). She had very high levels of EBV in her blood, and antivirals made no difference.
This chronic Epstein-Barr patient was referred to Dr Fluge: she was give rituximab, and sweated profusely for two days, but by the third day felt completely healthy.
So it is clear that when a patient's symptoms are due to chronic Epstein-Barr virus infection of the B-cells, rituximab cures their symptoms in a matter of days.
But with ME/CFS patients, it takes 7 to 8 months before the cure or improvements manifest.
So Dr Fluge says in his view, B-cell infection is not directly causing the symptoms of ME/CFS, but says he thinks viral infection does have something to do with ME/CFS, though he thinks it is the immune response after infection that is the driving factor, probably targeting and causing a dysfunction in the energy metabolism.