many of these antiretroviral drugs have anti-viral effects, so the benefit may be coming for other reasons.
Yes, tenofovir for example strongly reduces IL-10 (a Th2 cytokine), but increases levels of IL-12 (a Th1 cytokine). So tenofovir seems to act as a Th2 to Th1 immunomodulator (like oxymatrine is thought to be), and would likely be good at fighting any virus in ME/CFS, including enteroviruses, HHV-6, cytomegalovirus and EBV. It also has anti-inflammatory effects. Ref: 1
In this respect, I think if ME/CFS patients are reporting benefits on tenofovir, it's perhaps something that needs to be investigated further. Tenofovir might be make a good immunomodulatory add-on to oxymatrine, to support oxymatrine.
Tenofovir has an effect against human endogenous retroviruses (HERVs), and Dr Brigitte Huber showed that there is increased HERV-K18 activity in the post-mononucleosis subset of ME/CFS. So for that subset, tenofovir's anti-HERV effects could conceivably be helping.
Interestingly enough, Dr Huber was also one of the researchers who found she was unable to replicate Judy Mikovits's results.