CD4 and infection: For example, Vif promotes the degradation of the host restriction factor Apolipoprotein B mRNA editing enzyme catalytic polypeptide-like 3G (APOBEC3G); Vpu reduces Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling, modulates DNA repair and facilitates viral release from infected cells by downregulating the restriction factor Tetherin; Vpr promotes infection of macrophages and manipulates the cell cycle; and Nef ensures T cell activation and downregulates CD4 surface expression [53,54,55,56,57,58,59,60,61].