USE OF MURINE CXCR-4 AS A 2ND RECEPTOR BY SOME T-CELL-TROPIC HUMAN IMMUNODEFICIENCY VIRUSES

The human CXCR-4 molecule serves as a second receptor for primary, T-c ell-tropic, and laboratory-adapted human immunodeficiency virus type 1 (HIV-1) isolates. Here we show that murine CXCR-4 can support the ent ry of some of these HIV-1 isolates. Differences between mouse and huma n CXCR-4 in the ability to function as an HIV-1 receptor are determine d by sequences in the second extracellular loop of the CXCR-4 protein.