Chemokine (C-C motif) ligand 4 encoded by the CCL4 gene, also known as macrophage inflammatory protein-1β (MIP-1β) is a CC chemokine with specificity for CCR5 receptors and it is a major HIV-suppressive factor produced by CD8+ T cells. In addition, it is a chemoattractant for natural killer cells, monocytes and a variety of other immune cells. Recombinant CCL4 induces a dose-dependent inhibition of different strains of HIV-1, HIV-2, and simian immunodeficiency virus (SIV). Furthermore, recombinant rat CCL4 contains 69 amino acids and it shares 80% and 86% a.a. sequence identity with human and murine CCL4. Both human and murine MIP-1α and MIP-1β are active on human and murine hematopoietic cells.