CD4-INDEPENDENT BINDING OF SIV GP120 TO RHESUS CCR5

CCR5 and CD4 are coreceptors for immunodeficiency virus entry into tar get cells, The gp120 envelope glycoprotein from human immunodeficiency virus strain HIV-1(YU2) bound human CCR5 (CCR5(hu)) or rhesus macaque CCR5 (CCR5(rh)) only in the presence of CD4. The gp120 from simian im munodeficiency virus strain SIVmac239 bound CCR5(rh) without CD4, but CCR5(hu) remained CD4-dependent. The CD4-independent binding of SIVmac 239 gp120 depended on a single amino acid, Asp(13), in the CCR5(rh) am ino-terminus. Thus, CCR5-binding moieties on the immunodeficiency viru s envelope glycoprotein can be generated by interaction with CD4 or by direct interaction with the CCR5 amino-terminus. These results may ha ve implications for the evolution of receptor use among lentiviruses a s well as utility in the development of effective intervention.