HIV-1 ENTRY COFACTOR - FUNCTIONAL CDNA CLONING OF A 7-TRANSMEMBRANE, G-PROTEIN-COUPLED RECEPTOR

A cofactor for HIV-1 (human immunodeficiency virus-type 1) fusion and entry was identified with the use of a novel functional complementary DNA (cDNA) cloning strategy. This protein, designated ''fusin,'' is a putative G protein-coupled receptor with seven transmembrane segments. Recombinant fusin enabled CD4-expressing nonhuman cell types to suppo rt HIV-1 Env-mediated cell fusion and HIV-1 infection. Antibodies to f usin blocked cell fusion and infection with normal CD4-positive human target cells. Fusin messenger RNA levels correlated with HIV-1 permiss iveness in diverse human cell types. Fusin acted preferentially for T cell line-tropic isolates, in comparison to its activity with macropha ge-tropic HIV-1 isolates.