Coren Lori V, Trivett Matthew T, Jain Sumiti, Ayala Victor I, Del Prete Gregory Q, Ohlen Claes, Ott David E
Retrovirology. 2015 Feb 7;12:11. doi: 10.1186/s12977-015-0137-9.
The TRIM5α protein is a principal restriction factor that contributes to an HIV-1 replication block in rhesus macaque CD4+ T cells by preventing reverse transcription. HIV-1 restriction is induced in human CD4+ T cells by expression of rhesus TRIM5α as well as those of other old world monkeys. While TRIM5α restriction has been extensively studied in single-round infection assays, fewer studies have examined restriction after extended viral replication.
To examine TRIM5α restriction of replication, we studied the ability of TRIM5α proteins from African green monkey (AgmTRIM5α) and gorilla (gorTRIM5α) to restrict HIV-1 and SIVmac239 replication. These xenogeneic TRIM5α genes were transduced into human Jurkat-CCR5 cells (JR5), which were then exposed to HIV-1 or SIVmac239. In our single-round infection assays, AgmTRIM5α showed a relatively modest 4- to 10-fold restriction of HIV-1 and SIVmac239, while gorTRIM5α produced a 2- and 3-fold restriction of HIV-1 and SIVmac239, respectively, consistent with the majority of previously published single-round studies. To assess the impact of these modest effects on infection, we tested restriction in replication systems initiated with either cell-free or cell-to-cell challenges. AgmTRIM5α powerfully restricted both HIV-1 and SIVmac239 replication 14 days after cell-free infection, with a ≥ 3-log effect. Moreover, expression of AgmTRIM5α restricted HIV-1 and SIVmac239 replication by 2-logs when co-cultured with infected JR5 cells for 12 days. In contrast, neither expression of gorTRIM5α nor rhesus TRIM5α induced significant resistance when co-cultured with infected cells. Follow up experiments showed that the observed differences between replication and infection were not due to assembly defects as xenogeneic TRIM5α expression had no effect on either virion production or specific infectivity.
Our results indicate that AgmTRIM5α has a much greater effect on extended replication than on any single infection event, suggesting that AgmTRIM5α restriction acts cumulatively, building up over many rounds of replication. Furthermore, AgmTRIM5α was able to potently restrict both HIV-1 and SIV replication in a cell-to-cell infection challenge. Thus, AgmTRIM5α is unique among the TRIM5α species tested to date, being able to restrict even at the high multiplicities of infection presented by mixed culture with nonrestrictive infected cells.
TRIM5α 蛋白是一种主要的限制因子，通过阻止逆转录来促成恒河猴 CD4+ T 细胞中 HIV-1 复制受阻。恒河猴 TRIM5α 以及其他旧世界猴的 TRIM5α 在人类 CD4+ T 细胞中可诱导 HIV-1 限制。虽然在单轮感染试验中对 TRIM5α 限制进行了广泛研究，但较少有研究考察长时间病毒复制后的限制情况。
为了研究 TRIM5α 对复制的限制作用，我们研究了来自非洲绿猴（AgmTRIM5α）和大猩猩（gorTRIM5α）的 TRIM5α 蛋白限制 HIV-1 和 SIVmac239 复制的能力。这些异种 TRIM5α 基因被转导到人 Jurkat-CCR5 细胞（JR5）中，然后将这些细胞暴露于 HIV-1 或 SIVmac239。在我们的单轮感染试验中，AgmTRIM5α 对 HIV-1 和 SIVmac239 显示出相对适度的 4 至 10 倍限制，而 gorTRIM5α 对 HIV-1 和 SIVmac239 分别产生 2 倍和 3 倍的限制，这与大多数先前发表的单轮研究结果一致。为了评估这些适度效应对感染的影响，我们在无细胞或细胞间挑战启动的复制系统中测试了限制情况。无细胞感染 14 天后，AgmTRIM5α 有力地限制了 HIV-1 和 SIVmac239 的复制，效应≥3 个对数。此外，与感染的 JR5 细胞共培养 12 天时，AgmTRIM5α 的表达使 HIV-1 和 SIVmac239 的复制受到 2 个对数的限制。相比之下，与感染细胞共培养时，gorTRIM5α 和恒河猴 TRIM5α 的表达均未诱导出显著抗性。后续实验表明，观察到的复制和感染之间的差异并非由于组装缺陷，因为异种 TRIM5α 的表达对病毒粒子产生或特异性感染性均无影响。
我们的结果表明，AgmTRIM5α 对延长复制的影响比对任何单个感染事件的影响大得多，这表明 AgmTRIM5α 限制具有累积作用，在多轮复制过程中逐渐增强。此外，在细胞间感染挑战中，AgmTRIM5α 能够有效限制 HIV-1 和 SIV 的复制。因此，AgmTRIM5α 在迄今为止测试的 TRIM5α 物种中是独特的，即使在与无限制感染细胞混合培养所呈现的高感染复数情况下也能发挥限制作用。
