Lin Wei-Li, Chien Maw-Sheng, Wu Pei-Ching, Lai Chen-Li, Huang Chienjin
Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan.
Open Virol J. 2011;5:148-53. doi: 10.2174/1874357901105010148. Epub 2011 Dec 13.
Porcine circovirus type 2 (PCV2) is the primary causative agent of porcine circovirus-associated diseases in pigs. To analyze whether the PCV2 nonstructural protein ORF3 is able to induce apoptosis in nature target cells, transient expression of ORF3 in porcine peripheral blood mononuclear cells (PBMC) was performed, and apoptosis was confirmed by terminal dexoynucleotidyl transferase (TdT)-mediated BrdUTP-nick end labeling (TUNEL) assay. The apoptotic responses induced by the full length or the C-terminal half of ORF3 were significantly higher (p < 0.001) than that of cells transfected with the control plasmid. In contrast, the N-terminal half of ORF3 restrictively localized in the cytoplasm and remarkably reduced its ability to induce apoptosis, the apoptotic activity might be correlated with the nuclear localization of ORF3. Furthermore, two clusters of basic residues on the C-terminal half region at the amino acid residues 53-68 and 85-104 could mediate the nuclear localization of fusion protein, confirming their potential role as a nuclear localization signal.
猪圆环病毒2型（PCV2）是猪圆环病毒相关疾病的主要病原体。为分析PCV2非结构蛋白ORF3是否能够在天然靶细胞中诱导凋亡，研究人员在猪外周血单核细胞（PBMC）中进行了ORF3的瞬时表达，并通过末端脱氧核苷酸转移酶（TdT）介导的BrdUTP缺口末端标记（TUNEL）试验确认了凋亡情况。全长ORF3或其C末端一半诱导的凋亡反应显著高于（p < 0.001）转染对照质粒的细胞。相反，ORF3的N末端一半局限于细胞质中，显著降低了其诱导凋亡的能力，凋亡活性可能与ORF3的核定位有关。此外，在氨基酸残基53 - 68和85 - 104的C末端一半区域上的两簇碱性残基可介导融合蛋白的核定位，证实了它们作为核定位信号的潜在作用。
