Fischer P B, Karlsson G B, Dwek R A, Platt F M
Department of Biochemistry, Glycobiology Institute, University of Oxford, United Kingdom.
J Virol. 1996 Oct;70(10):7153-60. doi: 10.1128/JVI.70.10.7153-7160.1996.
The alpha-glucosidase inhibitor N-butyldeoxynojirimycin (NB-DNJ) is an inhibitor of human immunodeficiency virus (HIV) replication and HIV-induced syncytium formation in vitro. Although an NB-DNJ-mediated change in viral envelope N-glycan composition inhibits HIV entry at the level of post-CD4 binding, the exact mechanism of inhibition remains to be established. In this study we have examined the effects of NB-DNJ on virion envelope composition and CD4-induced gp120 shedding and gp41 exposure. Virion composition analysis revealed an NB-DNJ-mediated reduction of 15% in overall virion envelope glycoprotein content and a reduction of 26% in the proteolytic maturation of virion gp160. Taken together, these two effects resulted in a reduction of approximately 40% in virion gp120 content. CD4-induced shedding of gp120 from the surfaces of envelope-transfected Cos cells was undetectable when gp120 was expressed in the presence of NB-DNJ. Similarly, the shedding of virion-associated gp120 was reduced 7.4-fold. CD4-induced exposure of cryptic gp41 epitopes on the surfaces of HIV-expressing ACH-2 cells was also greatly impaired, and the exposure of virion-associated gp41 epitopes was reduced 4.0-fold. Finally, CD4-induced increases in the binding of antibodies to the V3 loop of ACH-2-cell-expressed envelope glycoproteins were reduced 25-fold when the glycoproteins were expressed in the presence of NB-DNJ. These results suggest that the NB-DNJ-mediated retention of glycosylated N-glycans inhibits HIV entry by a combined effect of a reduction in virion gp120 content and a qualitative defect within the remaining gp120, preventing it from undergoing conformational changes after CD4 binding.
α-葡萄糖苷酶抑制剂N-丁基脱氧野尻霉素（NB-DNJ）在体外是人类免疫缺陷病毒（HIV）复制及HIV诱导的合胞体形成的抑制剂。尽管NB-DNJ介导的病毒包膜N-聚糖组成变化在CD4结合后水平抑制HIV进入，但确切的抑制机制仍有待确定。在本研究中，我们检测了NB-DNJ对病毒粒子包膜组成以及CD4诱导的gp120脱落和gp41暴露的影响。病毒粒子组成分析显示，NB-DNJ介导病毒粒子包膜糖蛋白总含量降低15%，病毒粒子gp160的蛋白水解成熟降低26%。综合这两种效应，导致病毒粒子gp120含量降低约40%。当在NB-DNJ存在的情况下表达gp120时，在包膜转染的Cos细胞表面未检测到CD4诱导的gp120脱落。同样，病毒粒子相关gp120的脱落减少了7.4倍。在表达HIV的ACH-2细胞表面，CD4诱导的隐蔽gp41表位暴露也受到极大损害，病毒粒子相关gp41表位的暴露减少了4.0倍。最后，当在NB-DNJ存在的情况下表达糖蛋白时，CD4诱导的抗体与ACH-2细胞表达的包膜糖蛋白V3环结合增加减少了25倍。这些结果表明，NB-DNJ介导的糖基化N-聚糖保留通过降低病毒粒子gp120含量以及剩余gp120内的质量缺陷的联合效应抑制HIV进入，从而阻止其在CD4结合后发生构象变化。
