“…These include HLA-type (1)(2)(3)(4), HIV co-receptor expression (5), the cytidine deaminase APOBEC3G (6,7), tetherin (BST-2) (8), SAMHD1 (9,10), and an array of cytokines. Some cytokines such as type 1 and type 3 interferons, chemokines (e.g., stromal cell-derived factor 1, macrophage inflammatory factor 1a, RANTES (regulated on activation normal T cell expressed and secreted), and IL-27) inhibit HIV replication (11)(12)(13), whereas some enhance replication (IL-6 (14), tumor necrosis factor-␣ (15), IL-12 (16), and colony-stimulating factors (17,18)), and some are capable of either inhibiting or enhancing replication depending upon the culture system and conditions. In this regard, IL-2 has been shown to be capable of suppressing HIV-1 replication through the enhancement of CD8ϩ T cell function and enhancing HIV-1 replication in primary cultures of CD4ϩ T cells (19 -21).…”