CCL4 and HIV-1 infection: The first encounter between the fields of HIV and chemokines occurred unexpectedly at the end of 1995 with the discovery that three chemokines of the CC family, RANTES (CC-chemokine ligand 5 or CCL5), MIP-1α (CCL3) and MIP-1β (CCL4), act as potent and specific natural inhibitors of HIV-1 infection [1].