Small amino acid changes in the V3 loop of human immunodeficiency virus type 2 determines the coreceptor usage for CXCR4 and CCR5

HIV-2 GH-1 is a molecular clone derived from an AIDS patient from Ghana. In contrast to the prototypic molecular clone ROD, GH-1 exhibits a narrow ran ge of target cell specificity. By an infectious assay using HeLa-CD4 cells stably transfected with an HIV-1 LTR-beta-galactosidase reporter gene and t ransiently expressing various cloned chemokine receptors, we have examined the coreceptor usage of GH-1. In contrast to ROD, which uses principally CX CR4, GH-1 was found to use mainly if not exclusively CCR5 but not CXCR4. Th e distinct coreceptor usage of these two molecular clones allowed us to fur ther map the region of gp120 that is important for the coreceptor specifici ty. By constructing a series of chimeric viruses between GH-1 and ROD, we h ave demonstrated that the C-terminal half of the V3 loop region of gp120 de termines the differential coreceptor usage between GH-1 and ROD, and only a few amino acid differences in this region appear to be able to shift the s pecificity between CCR5 and CXCR4. Notably, the shift in the coreceptor usa ge from CCR5 to CXCR4 is associated with an increase in the net positive ch arge in the V3 region. (C) 1999 Academic Press.