Abstract: Objective: To explore the biological activities of viral macrophage inflammatory protein(vMIP) encoded by K6 gene of human herpesvirus 8.Methods: Combined ability of vMIP to receptors was measured by Cross-linking assays.Biological activity of vMIP were measured with Cellular chemotaxis assays and calcium mobilization.Results: Cross-linking assays showed that vMIP bound with receptors of peripheral blood mononuclear,and vMIP suppressed by chemotacitic activity of PBMCs to human macrophage inflammatory protein(hMIP-1α) and EC₅₀=3.39 ng/ml.But itself was not remarkably associated with the normal,rapid mobilization of calcium from intracellular stores.Instead,it blocked calcium mobilization induced by endogenous chemokines.Conclusions: The study has demonstrated that vMIP can bind to receptor of hMIP-1(CCR5) and stop it from hMIP-1 and conduction of messages.But itself did not induce cellular chemotaxis,meaning that vMIP has ability of binding to CCR5 similar hMIP-1α and absent of function activating receptor like hMIP-1α,so vMIP only has sealing effect on CCR5.This also suggests that only of effects of vMIP is to seal CCR5 of host cells,vMIP is the natural sealing factor for CCR5 and result in inhibiting inflammatory reaction mediated by interaction between CCR5 and human MIPs,so possibly it is important value in prevention and treatment of inflammation,transplantion immunity and HIV infection.