Human immunodeficiency virus strains differ in their ability to infect CD4+ cells expressing the rat homolog of CXCR-4 (fusin)

A clade B strain of human immunodeficiency virus type 1 (HIV-1(LAI)) could infect CD4+ cells expressing human CXCR-4 (fusin) or its rat homolog with similar efficacy. By contrast, cells expressing rat CXCR-4 were not permissive to HIV-1(NDK) (clade D), HIV-2(ROD), or HIV-1(LAI) with chimeric envelope protein gp120 bearing the V3 domain from HIV-1(NDK). The reciprocal chimeric gp120 (HIV-1(NDK) with V3 from HIV-1(LAI)) could mediate infection of cells expressing either human or rat CXCR-4. Genetically divergent HIV strains have different requirements for interaction with the CXCR-4 coreceptor, and the gp120 V3 domain seems to be involved in this interaction.