CD4 and AIDS: HIV-1 emerged through cross-species transmission of SIV to humans (1), leading to massive CD4+ T-cell loss, inflammation, and chronic immune activation in the gut and systemically, which altogether eventually lead to an exhaustion of the immune system and the development of opportunistic infections and AIDS-associated comorbidities, such as hypercoagulation and other cardiovascular diseases, hyperlipidemia, chronic kidney and hepatic diseases, osteoporosis, endocrine diseases, and cancers (10, 11).