Xiao L, Owen S M, Goldman I, Lal A A, deJong J J, Goudsmit J, Lal R B
Retrovirus Diseases Branch, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
Virology. 1998 Jan 5;240(1):83-92. doi: 10.1006/viro.1997.8924.
The cellular tropism of human immunodeficiency virus type 1 (HIV-1) is dependent on utilization of specific chemokine co-receptor: macrophage-tropic/non-syncytium-inducing (NSI) viruses use CCR5, whereas T-cell tropic/syncytium-inducing (SI) viruses preferentially use CXCR4. We have analyzed co-receptor usage of 24 phylogenetically distinct primary HIV-1 isolates representing group M (clades A-F) and group O with known SI and NSI phenotype, using lymphocytes from donor with nonfunctional CCR5 (CCR5-/-; homozygous 32-bp deletion). While all SI isolates infected CCR5-/- lymphocytes (and hence do not require CCR5 for viral entry), all NSI isolates, regardless of clade, did not infect CCR5-/- lymphocytes. Thus, CCR5 expression is required for infection with NSI isolates and the CCR5 usage is independent of viral genotype. To localize the viral determinant involved in CCR5 binding, the V3 sequences across the clades were aligned based on the CCR5 usage. There were conserved uncharged residues at position 11 of V3 (mostly serine/glycine) and negatively charged residues at residue 25 (mostly glutamic/aspartic acid) among all isolates that used CCR5, whereas substitution with arginine or glutamine at these two positions led to usage of a co-receptor other than CCR5. This analysis led us to identify a consensus motif S/GXXXGPGXXXXXXXE/D within the V3 loop that predicts CCR5 co-receptor usage. Most isolates, with exception of one isolate, containing the conserved motif and predicted to utilize CCR5 indeed had an absolute requirement of CCR5 expression for infectibility. Site-directed mutagenesis in the infectious molecular clone further confirmed these results. Taken together, these data provide evidence that sequences within the V3 loop provide important residues that might be directly or indirectly involved in binding to a CCR5 co-receptor.
1型人类免疫缺陷病毒（HIV-1）的细胞嗜性取决于特定趋化因子共受体的利用：巨噬细胞嗜性/非合胞体诱导（NSI）病毒使用CCR5，而T细胞嗜性/合胞体诱导（SI）病毒优先使用CXCR4。我们使用来自CCR5功能缺失供体（CCR5-/-；纯合32bp缺失）的淋巴细胞，分析了24株系统发育上不同的原发性HIV-1分离株的共受体使用情况，这些分离株代表M组（A-F亚型）和O组，具有已知的SI和NSI表型。虽然所有SI分离株都能感染CCR5-/-淋巴细胞（因此病毒进入不需要CCR5），但所有NSI分离株，无论其亚型如何，都不能感染CCR5-/-淋巴细胞。因此，NSI分离株的感染需要CCR5表达，且CCR5的使用与病毒基因型无关。为了定位参与CCR5结合的病毒决定簇，根据CCR5的使用情况对各亚型的V3序列进行比对。在所有使用CCR5的分离株中，V3区第11位存在保守的不带电荷残基（大多为丝氨酸/甘氨酸），第25位存在带负电荷残基（大多为谷氨酸/天冬氨酸），而这两个位置被精氨酸或谷氨酰胺取代会导致使用CCR5以外的共受体。该分析使我们确定了V3环内一个预测CCR5共受体使用情况的共有基序S/GXXXGPGXXXXXXXE/D。除一株分离株外，大多数含有保守基序并预测使用CCR5的分离株确实绝对需要CCR5表达才能具有感染性。感染性分子克隆中的定点诱变进一步证实了这些结果。综上所述，这些数据证明V3环内的序列提供了可能直接或间接参与与CCR5共受体结合过程的重要残基。
