Institute of Immunology and College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China; MOA Key Laboratory of Animal Virology, Institute of Preventive Veterinary Science, Department of Veterinary Medicine, Zhejiang University, Hangzhou, China.
Institute of Immunology and College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.
Vet Microbiol. 2020 Jul;246:108692. doi: 10.1016/j.vetmic.2020.108692. Epub 2020 May 17.
Porcine circovirus type 2 (PCV2) capsid protein (Cap) was previously reported to interact with nucleosome assembly protein 1-like 4 (NAP1L4). The biological function of Cap-NAP1L4 interaction is unknown. Here, we demonstrated that PCV2 Cap could directly interact with NAP1L4, which the amino acid residues 124-279 of NAP1L4 were responsible for the interaction. Furthermore, over-expression of NAP1L4 down-regulated the expression of PCV2 Cap and Rep. DNA copies and virus titers were also decreased in NAP1L4 over-expressed PK15 cells. While, knockout of NAP1L4 through CRISPR/Cas9 technology in PK15 cells could up-regulate the mRNA and protein levels of PCV2 Cap and Rep. PCV2 genomic DNA copies and virus titers were also increased in NAP1L4-knockdown/-knockout PK15 cells compared with wild type PK15 cells. In addition, NAP1L4 depletion was demonstrated to facilitate cytosolic carboxypeptidase-like protein 5 (CCP5) and cytosolic carboxypeptidase 6 (CCP6) expression, which could activate cGAS to promote IFN-β production. Indeed, knockout of NAP1L4 was also confirmed to increase IFN-β expression. And IFN-β stimulation could promote PCV2 replication in PK15 cells. Taken together, our findings suggest that NAP1L4 interacts with PCV2 Cap and inhibits PCV2 replication through regulating IFN-β production. Our study provides theoretical basis for further study of PCV2.
猪圆环病毒 2 型（PCV2）衣壳蛋白（Cap）先前被报道与核小体装配蛋白 1 样 4（NAP1L4）相互作用。Cap-NAP1L4 相互作用的生物学功能尚不清楚。在这里，我们证明了 PCV2 Cap 可以与 NAP1L4 直接相互作用，而 NAP1L4 的氨基酸残基 124-279 负责这种相互作用。此外，NAP1L4 的过表达下调了 PCV2 Cap 和 Rep 的表达。NAP1L4 过表达 PK15 细胞中的 PCV2 Cap 和 Rep DNA 拷贝数和病毒滴度也降低。然而，通过 CRISPR/Cas9 技术敲除 NAP1L4 在 PK15 细胞中可以上调 PCV2 Cap 和 Rep 的 mRNA 和蛋白水平。与野生型 PK15 细胞相比，PCV2 基因组 DNA 拷贝数和病毒滴度在 NAP1L4 敲除/-敲除 PK15 细胞中也增加。此外，NAP1L4 的耗竭被证明可以促进细胞质羧肽酶样蛋白 5（CCP5）和细胞质羧肽酶 6（CCP6）的表达，这可以激活 cGAS 以促进 IFN-β 的产生。事实上，敲除 NAP1L4 也被证实可以增加 IFN-β 的表达。IFN-β 刺激可以促进 PK15 细胞中的 PCV2 复制。总之，我们的研究结果表明，NAP1L4 与 PCV2 Cap 相互作用，并通过调节 IFN-β 的产生来抑制 PCV2 的复制。我们的研究为进一步研究 PCV2 提供了理论依据。
