Sun Y, Pinchuk L M, Agy M B, Clark E A
Washington Regional Primate Research Center, University of Washington, Seattle 98195, USA.
J Immunol. 1997 Jan 1;158(1):512-7.
Using PCR to monitor early (LTR/LTR (long terminal repeat)) and late (LTR/gag) products of reverse transcription and the formation of HIV-1 LTR circles (indicating nuclear import), we explored the relationship between T cell activation signals and early events in the life cycle of HIV-1 infection. The combination of TCR ligation with either CD28 cross-linking or exogenous IL-2 was required for HIV-1 LTR circle formation in resting CD4+ T cells. Ligation of the TCR or CD28 receptors or addition of IL-2 alone did not induce this process. However, cross-linking the TCR, or IL-2 alone, unlike CD28 ligation, could induce the completion of viral reverse transcription. In contrast, the initiation of HIV-1 reverse transcription could occur in resting CD4+ T cells without any stimulation. Cyclosporin A (CsA), an inhibitor of T cell activation, completely blocked HIV-1 DNA nuclear import in activated CD4+ T cells. The completion of HIV-1 reverse transcription was blocked by CsA in infected CD4+ T cells activated by TCR ligation and IL-2, but not in cells stimulated by TCR and CD28 ligation. The costimulation of CD3 and CD28 mAbs in the presence of IL-2 could not overcome the CsA inhibitory effect on nuclear import of viral DNA. Therefore, the factor(s) involved in a CsA-sensitive pathway plays a critical role in HIV-1 DNA transport from the cytoplasm into the nucleus. Production and movement of HIV-1 DNA in resting CD4+ T cells require two signals: one signal from the TCR, which normally regulates the G0 to G1 transition, induces completion of viral reverse transcription; the other signal through CD28 or an IL-2R-dependent process is sensitive to CsA treatment and regulates viral DNA entry into the nucleus.
利用聚合酶链反应（PCR）监测逆转录的早期产物（长末端重复序列/LTR）和晚期产物（LTR/ gag）以及HIV-1 LTR环的形成（表明核输入），我们探究了T细胞激活信号与HIV-1感染生命周期早期事件之间的关系。在静息CD4+ T细胞中，HIV-1 LTR环的形成需要TCR连接与CD28交联或外源性白细胞介素-2（IL-2）相结合。单独连接TCR或CD28受体或添加IL-2均不能诱导此过程。然而，与CD28连接不同，交联TCR或单独使用IL-2可诱导病毒逆转录的完成。相比之下，HIV-1逆转录的起始可在未受任何刺激的静息CD4+ T细胞中发生。环孢素A（CsA）是一种T细胞激活抑制剂，可完全阻断激活的CD4+ T细胞中HIV-1 DNA的核输入。在由TCR连接和IL-2激活的感染CD4+ T细胞中，CsA可阻断HIV-1逆转录的完成，但在由TCR和CD28连接刺激的细胞中则不然。在IL-2存在的情况下，CD3和CD28单克隆抗体的共刺激无法克服CsA对病毒DNA核输入的抑制作用。因此，参与CsA敏感途径的因子在HIV-1 DNA从细胞质转运到细胞核的过程中起关键作用。HIV-1 DNA在静息CD4+ T细胞中的产生和移动需要两个信号：一个来自TCR的信号，通常调节G0到G1期的转变，诱导病毒逆转录的完成；另一个通过CD28或IL-2R依赖过程的信号对CsA处理敏感，并调节病毒DNA进入细胞核。
