Changes in and discrepancies between cell tropisms and coreceptor uses of human immunodeficiency virus type 1 induced by single point mutations at the V3 tip of the Env protein

We examined the effect of a mine acid substitutions of the GPGR (glycine-pr oline-glycine-arginine) tip sequence at the V3 domain of the Env protein of human immunodeficiency virus type 1 (HIV-1) on its cell tropism and corece ptor use. We changed the GPGR sequence of a T-cell line (T)- and macrophage (M)-tropic (R5-R3-X4) HIV-1 strain, GUN-1WT, to GA(alanine)GR (the resulti ng mutant was designated GUN-1/A), GL(leucine)GR (GUN-1/L), GP(proline)GR ( GUN-1/P), GR(arginine)GR (GUN-1/R), GS(serine)GR (GUN-1/S), or GT(threonine )GR (GUN-1/T). GUN-1/A, GUN-1/S, and GUN-1/T mutants infected brain-derived cells such as a CD4-transduced glioma cell line, U87/CD4, and a brain-deri ved primary cell strain, BT-20/N, as well as T-cell lines in a CD4-dependen t manner, although the plating of these mutants onto macrophages was inhibi ted. GUN-1/L, GUN-1/P, and GUN-1/R mutants showed both T- and M-tropism, bu t did not plate onto the brain-derived cells. A CCR3, CCR5, CCR8, or CXCR4 gene was introduced into a CD4-positive glioma cell line, NP-2/CD4, which d emonstrated complete resistance to various HIV-1 strains. Not only HIV-1 st rains, which were infectious to macrophages, such as GUN-1WT, GUN-1V, GUN-1 /L, and GUN-1/P, but also an HIV-1 strain, GUN-IV, which was hardly infecti ous to macrophages, grew well in NP-2/CD4 cells expressing CCR3 or CCRS. Ho wever, the M-tropic GUN-1/R mutant could not efficiently use CCR5 nor CCR3. No point mutants, except GUN-1/L, grew well in NP-2/CD4 cells expressing C CR8. These findings indicate that the cell tropism of HIV-1 to macrophages and brain-derived cells and their use of the coreceptors were markedly, tho ugh not always concomitantly, affected by the tip sequence of the V3 domain . (C) 1999 Academic Press.