When the pandemic started I did a deep dive on the last enduring global pandemic HIV. Previously classified as lentiviruses, literally meaning "long viruses," it took a lot of work and a bunch of well connected rich San Francisco gays being infected with the Great Ape borne HIV-M to discover the lymphocyte attacking retrovirus.
Retroviruses rewrite the genome of their host to reproduce, and many live in the host with no adverse health effects. A great example is HIV-P which originated in sooty mangabeys from the ivory coast. The locals that subsist on these monkeys for bushmeat, and some europeans for some unknown reason, are completely immune to HIV-P. HIV-P is the dominant HIV strain in africa due to sex trafficking and slavery in the region.
My research reached a lot of dead ends finding that a lot of retroviruses in the human genome haven't been sequenced or identified at all. I'm finding papers that patients with immune-mediated disorders go into remission when treated with antiretroviral drugs for a comorbid HIV or AIDS infection.
Why is this area of research so poor, a good chunk of our DNA is playground for retroviruses, some of them are causing disease that strip the myelin from our parents CNS in old age.