Litwin V, Nagashima K A, Ryder A M, Chang C H, Carver J M, Olson W C, Alizon M, Hasel K W, Maddon P J, Allaway G P
Progenics Pharmaceuticals, Inc., Tarrytown, New York 10591, USA.
J Virol. 1996 Sep;70(9):6437-41. doi: 10.1128/JVI.70.9.6437-6441.1996.
Previous studies of human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein-mediated membrane fusion have focused on laboratory-adapted T-lymphotropic strains of the virus. The goal of this study was to characterize membrane fusion mediated by a primary HIV-1 isolate in comparison with a laboratory-adapted strain. To this end, a new fusion assay was developed on the basis of the principle of resonance energy transfer, using HeLa cells stably transfected with gp120/gp41 from the T-lymphotropic isolate HIV-1LA1 or the macrophage-tropic primary isolate HIV-1JR-FL. These cells fused with CD4+ target cell lines with a tropism mirroring that of infection by the two viruses. Of particular note, HeLa cells expressing HIV-1JR-FL gp120/gp41 fused only with PM1 cells, a clonal derivative of HUT 78, and not with other T-cell or macrophage cell lines. These results demonstrate that the envelope glycoproteins of these strains play a major role in mediating viral tropism. Despite significant differences exhibited by HIV-1JR-FL and HIV-1LAI in terms of tropism and sensitivity to neutralization by CD4-based proteins, the present study found that membrane fusion mediated by the envelope glycoproteins of these viruses had remarkably similar properties. In particular, the degree and kinetics of membrane fusion were similar, fusion occurred at neutral pH and was dependent on the presence of divalent cations. Inhibition of HIV-1JR-FL envelope glycoprotein-mediated membrane fusion by soluble CD4 and CD4-IgG2 occurred at concentrations similar to those required to neutralize this virus. Interestingly, higher concentrations of these agents were required to inhibit HIV-1LAI envelope glycoprotein-mediated membrane fusion, in contrast to the greater sensitivity of HIV-1LAI virions to neutralization by soluble CD4 and CD4-IgG2. This finding suggests that the mechanisms of fusion inhibition and neutralization of HIV-1 are distinct.
先前关于1型人类免疫缺陷病毒（HIV-1）包膜糖蛋白介导的膜融合的研究主要集中在实验室适应的嗜T淋巴细胞病毒株。本研究的目的是比较一种原发性HIV-1分离株与一种实验室适应株介导的膜融合特性。为此，基于共振能量转移原理开发了一种新的融合试验，使用稳定转染了嗜T淋巴细胞分离株HIV-1LA1或嗜巨噬细胞原发性分离株HIV-1JR-FL的gp120/gp41的HeLa细胞。这些细胞与CD4+靶细胞系融合，其嗜性反映了两种病毒的感染嗜性。特别值得注意的是，表达HIV-1JR-FL gp120/gp41的HeLa细胞仅与HUT 78的克隆衍生物PM1细胞融合，而不与其他T细胞或巨噬细胞系融合。这些结果表明，这些毒株的包膜糖蛋白在介导病毒嗜性方面起主要作用。尽管HIV-1JR-FL和HIV-1LAI在嗜性和对基于CD4的蛋白中和的敏感性方面表现出显著差异，但本研究发现，这些病毒的包膜糖蛋白介导的膜融合具有非常相似的特性。特别是，膜融合的程度和动力学相似，融合在中性pH下发生，并且依赖于二价阳离子的存在。可溶性CD4和CD4-IgG2对HIV-1JR-FL包膜糖蛋白介导的膜融合的抑制发生在与中和该病毒所需浓度相似的浓度下。有趣的是，与HIV-1LAI病毒粒子对可溶性CD4和CD4-IgG2中和的更高敏感性相反，抑制HIV-1LAI包膜糖蛋白介导的膜融合需要更高浓度的这些试剂。这一发现表明，HIV-1的融合抑制和中和机制是不同的。
