Ruggli Nicolas, Bird Brian H, Liu Luzia, Bauhofer Oliver, Tratschin Jon-Duri, Hofmann Martin A
Institute of Virology and Immunoprophylaxis (IVI), Mittelhäusern, Switzerland.
Virology. 2005 Sep 30;340(2):265-76. doi: 10.1016/j.virol.2005.06.033.
Classical swine fever virus (CSFV) protects cells from double-stranded (ds) RNA-mediated apoptosis and IFN-alpha/beta induction. This phenotype is lost when CSFV lacks N(pro) (DeltaN(pro) CSFV). In the present study, we demonstrate that N(pro) counteracts dsRNA-mediated apoptosis and IFN-alpha/beta induction independently of other CSFV elements. For this purpose, we generated porcine SK-6 and PK-15 cell lines constitutively expressing N(pro) fused to the enhanced green fluorescent protein (EGFP). The survival of the SK6-EGFP-N(pro) cell line after polyinosinic polycytidylic acid [poly(IC)] treatment was comparable to that of CSFV-infected SK-6 cells and was significantly higher than the survival of the parent cell line. In PK-15 cells, the presence of EGFP-N(pro) prevented the DeltaN(pro) CSFV- and poly(IC)-mediated IFN-alpha/beta production. Importantly, N(pro) also inhibited IFN-alpha and IFN-beta promoter-driven luciferase expression in human cells and blocked IFN-alpha/beta induction mediated by Newcastle disease virus. This establishes a novel function for N(pro) in counteraction of the IFN-alpha/beta induction pathway.
经典猪瘟病毒（CSFV）可保护细胞免受双链（ds）RNA介导的凋亡以及干扰素α/β的诱导。当CSFV缺乏N(pro)（ΔN(pro) CSFV）时，这种表型就会丧失。在本研究中，我们证明N(pro)可独立于其他CSFV元件来对抗dsRNA介导的凋亡和干扰素α/β的诱导。为此，我们构建了稳定表达与增强型绿色荧光蛋白（EGFP）融合的N(pro)的猪SK-6和PK-15细胞系。经聚肌苷酸胞苷酸[poly(IC)]处理后，SK6-EGFP-N(pro)细胞系的存活率与感染CSFV的SK-6细胞相当，且显著高于亲代细胞系的存活率。在PK-15细胞中，EGFP-N(pro)的存在可阻止ΔN(pro) CSFV和poly(IC)介导的干扰素α/β的产生。重要的是，N(pro)还可抑制人细胞中干扰素α和干扰素β启动子驱动的荧光素酶表达，并阻断新城疫病毒介导的干扰素α/β的诱导。这确立了N(pro)在对抗干扰素α/β诱导途径中的新功能。
