A replication-competent, neutralization-sensitive variant of simian immunodeficiency virus lacking 100 amino acids of envelope
A replication-competent, neutralization-sensitive variant of simian immunodeficiency virus lacking 100 amino acids of envelope
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DOI：
10.1128/jvi.76.5.2075-2086.2002
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发表时间：
2002-03-01
影响因子：
5.4
通讯作者：
Desrosiers, RC
中科院分区：
文献类型：
--
作者：
Johnson, WE;Morgan, J;Desrosiers, RC
从猴免疫缺陷病毒（SIV）239株（SIVmac 239）中删除了gp 120包膜糖蛋白前两个可变环的编码序列。该缺失包括100个氨基酸。所产生的病毒在转染到永生化T细胞系中后复制较差，仅在25至30天后出现复制高峰。SIVmac 239 DeltaV 1V 2在培养物中的有限传代产生了一种变体，其具有显著改善的复制动力学，但保留了gp 120中原始的100个氨基酸缺失。克隆和测序结果表明，它的变化，包括在gp 120（5个取代）和gp 41（6个取代）的氨基酸取代的信封。预测gp 120的五个变化中的四个位于推定的辅助受体结合结构域内和周围，该区域被认为是由天然包膜复合物中的VI和V2环覆盖的。重组克隆的分析令人惊讶地揭示，gp 41的变化足以克服由gp 120的V1和V2环缺失产生的复制缺陷。SIVmac 239 DeltaV 1 V2包膜显示其介导细胞-细胞融合的能力显着降低，SIVmac 239 DeltaV 1 V2的感染滴度比亲本SIVmac 239的感染滴度低约四到八倍。尽管SIVmac 239强烈依赖于CD 4和辅助受体进入，但缺乏V1和V2环的包膜蛋白能够介导与CD 4（-）CCR 5（+）细胞的融合，其水平是在CD 4（+）CCR 5（+）细胞中观察到的水平的60%。来自SIVmac 239感染的猴子的血浆在中和SIVmac 239 DeltaV 1V 2方面比SIVmac 239有效至少100至1,000倍。这些结果证明了SIVmac 239的V1-V2序列对于病毒复制的可分配性，V1和V2在屏蔽包膜的辅助受体结合区中的作用，以及缺乏这些序列的SIV对抗体介导的中和的极端敏感性。
Coding sequences for the first two variable loops of the gp120 envelope glycoprotein were removed from simian immunodeficiency virus (SIV) strain 239 (SIVmac239). This deletion encompassed 100 amino acids. The resulting virus replicated poorly after transfection into immortalized T-cell lines, with peak replication occurring only after 25 to 30 days. Limited passaging of SIVmac239DeltaV1V2 in cultures gave rise to a variant which had significantly improved replication kinetics but which retained the original 100-amino-acid deletion in gp120. Cloning and sequencing revealed It changes in the envelope, including amino acid substitutions in both gp120 (5 substitutions) and gp41(6 substitutions). Four of the five changes in gp120 are predicted to lie within and around the putative coreceptor binding domain, a region which is believed to be covered by the VI and V2 loops in the native envelope complex. Analysis of recombinant clones surprisingly revealed that the changes in gp41 were sufficient to overcome the replication deficiency created by deletion of the V1 and V2 loops from gp120. The SIVmac239DeltaV1V2 envelope displayed a significant reduction in its ability to mediate cell-cell fusion, and the infectious titer of SIVmac239DeltaV1V2 was approximately four- to eightfold lower than that of parental SIVmac239. Although SIVmac239 is strongly dependent on both CD4 and a coreceptor for entry, envelope protein lacking the V1 and V2 loops was able to mediate fusion with CD4(-) CCR5(+) cells at 60% the level observed with CD4(+) CCR5(+) cells. Plasma from SIVmac239-infected monkeys was at least 100 to 1,000 times more effective at neutralizing SIVmac239DeltaV1V2 than SIVmac239. These results demonstrate the dispensability of the V1-V2 sequences of SIVmac239 for viral replication, a role for V1 and V2 in shielding the coreceptor binding region of the envelope, and the extreme sensitivity of a SIV lacking these sequences to antibody-mediated neutralization.