FIG. 1.

Infection of U373MG-CD4 cells expressing human or rat CXCR4 or the derived chimeric receptors HHRH and RRHR by HIV-1 strains LAI and NDK or derivatives with substitutions of the gp120 V3 loop. Cells were infected with approximately 1,000 I.U. per well (12-well plates) and stained with X-Gal after another 48 h. Blue-stained cells, representing HIV-1-infected cells, were scored in duplicate wells. Bars represent means of three independent transfections.