Inhibition of M-tropic HIV-1 infection by the fd phage-gene 3 protein withMIP-1 alpha-binding activity

CCR5 is a chemokine receptor with seven transmembrane-domains. II is expres sed on T cells and macrophages and functions as the principal co-receptor f or macrophage (M)-tropic strains of HIV-1. The anti-CCR5 monoclonal antibod y (mAb) 2D7 inhibits the binding and chemotaxis of the three natural beta-c hemokine ligands of CCR5, macrophage inflammatory protein (MIP)-1 alpha, MI P-1 beta, and RANTES, to CCR5(+) cells. The mAb also efficiently blocks the infectivity of several M-tropic and dual-tropic HIV-1 strains in vitro. In this study, we attempted to determine the peptide motif recognized with the 2D7 mAb. We isolated phage clones by panning a phage display library us ing 2D7 and identified three peptide motifs. One of these phage clones (M23 ) showed a marked inhibitory activity on HIV-1 infection. The unique sequen ce of 15 amino acids with an internal disulfide bond was inserted in the g3 p of the M23 phage clone (M23-g3p). The M23-g3p was purified by fast-perfor mance liquid chromatography (FPLC). We show here that (1) M23-g3p was speci fically recognized with anti-CCR5 mAb; (2) M23-g3p showed inhibitory activi ty on the infectivity of M-tropic but not T-tropic HIV-1 strains; (3) M23-g 3p bound to MIP-1 alpha, MIP-1 beta, and RANTES but not MCP-1. These result s suggested that the M23-g3p might mimic the CCR5-binding domain shared by beta-chemokines, MIP-1 alpha, MIP-1 beta, and RANTES as well as the HIV-1 i nfection. (C) 2000 Elsevier Science Ltd. All rights reserved.