Background: HIV-1 TAT protein is essential for the regulation of viral genome transcription. The first exon of TAT protein has a fundamental role in the stimulation of the extrinsic and intrinsic apoptosis pathways, but its anti-HIV activity is not clear yet.

Methods: In the current study, we firstly cloned the first exon of the TAT coding sequence in the pET-24a expression vector and then protein expression was done in the Rosetta expression host. Next, the expressed TAT protein was purified by Ni-NTA column under native conditions. After that, the protein yield was determined by Bradford kit and NanoDrop spectrophotometry. Finally, the cytotoxicity effect and anti-Scr-HIV-1 activity of the recombinant TAT protein alone and along with Tenofovir drug were assessed by MTT and ELISA, respectively.

Results: The recombinant TAT protein was successfully generated in E. coli, as confirmed by 13.5% SDS-PAGE and western blotting. The protein yield was ~150-200 μg/ml. In addition, the recombinant TAT protein at a certain dose with low toxicity could suppress Scr-HIV replication in the infected HeLa cells (~30%) that was comparable with a low toxic dose of Tenofovir drug (~40%). It was interesting that the recombinant TAT protein could enhance anti-HIV potency of Tenofovir drug up to 66%.

Conclusion: Generally, a combination of TAT protein and Tenofovir drug could significantly inhibit HIV-1 replication. It will be required to determine their mechanism of action in the next studies.

背景：HIV-1 TAT 蛋白对于调节病毒基因组转录至关重要。TAT 蛋白的第一个外显子在刺激外源性和内源性细胞凋亡途径中具有重要作用，但其抗 HIV 活性尚不清楚。

方法：在本研究中，我们首先在 pET-24a 表达载体中克隆了 TAT 编码序列的第一个外显子，然后在 Rosetta 表达宿主中进行蛋白质表达。接下来，在天然条件下通过 Ni-NTA 柱纯化表达的 TAT 蛋白。之后，通过 Bradford 试剂盒和 NanoDrop 分光光度法测定蛋白质产量。最后，分别通过MTT和ELISA评估重组TAT蛋白单独和与替诺福韦药物一起的细胞毒性作用和抗Scr-HIV-1活性。

结果：重组TAT蛋白在大肠杆菌中成功产生，经13.5% SDS-PAGE和蛋白质印迹证实。蛋白质产量为~150-200 μg/ml。此外，具有低毒性的特定剂量的重组 TAT 蛋白可以抑制受感染的 HeLa 细胞中的 Scr-HIV 复制（~30%），这与低毒性剂量的替诺福韦药物（~40%）相当。有趣的是，重组 TAT 蛋白可以将替诺福韦药物的抗 HIV 效力提高 66%。

结论：一般而言，TAT蛋白与替诺福韦药物联合使用可显着抑制HIV-1复制。在接下来的研究中需要确定它们的作用机制。