Moulin Hervé R, Seuberlich Torsten, Bauhofer Oliver, Bennett Lea C, Tratschin Jon-Duri, Hofmann Martin A, Ruggli Nicolas
Institute of Virology and Immunoprophylaxis, Sensemattstrasse 293, CH-3147 Mittelhäusern, Switzerland.
Virology. 2007 Sep 1;365(2):376-89. doi: 10.1016/j.virol.2007.03.056. Epub 2007 May 4.
The nonstructural protein NS2-3 of pestiviruses undergoes tightly regulated processing. For bovine viral diarrhea virus it was shown that uncleaved NS2-3 is required for infectious particle formation while cleaved NS3 is essential for genome replication. To further investigate the functions of NS2-3 and NS4A in the pestivirus life cycle, we established T7 RNA polymerase-dependent trans-complementation for p7-NS2-3-4A of classical swine fever virus (CSFV). Expression of NS2-3 and NS4A in trans restored the production of infectious particles from genomes lacking NS2-3 expression. Co-expression of cleaved NS4A was essential. None of the enzymatic activities harbored by NS2-3 were required for infectious particle formation. Importantly, expression of uncleavable NS2-3 together with NS4A rescued infectious particles from a genome lacking NS2, demonstrating that cleaved NS2 per se has no additional essential function. These data indicate that NS2-3 and NS3, each in association with NS4A, have independent functions in the CSFV life cycle.
瘟病毒的非结构蛋白NS2-3经历严格调控的加工过程。对于牛病毒性腹泻病毒，已表明未切割的NS2-3是感染性粒子形成所必需的，而切割后的NS3对基因组复制至关重要。为了进一步研究NS2-3和NS4A在瘟病毒生命周期中的功能，我们针对经典猪瘟病毒（CSFV）的p7-NS2-3-4A建立了T7 RNA聚合酶依赖性反式互补体系。反式表达NS2-3和NS4A可恢复缺乏NS2-3表达的基因组产生感染性粒子的能力。切割后的NS4A的共表达至关重要。感染性粒子形成不需要NS2-3所具有的任何酶活性。重要的是，不可切割的NS2-3与NS4A共同表达可从缺乏NS2的基因组中拯救出感染性粒子，这表明切割后的NS2本身没有其他必需功能。这些数据表明，NS2-3和NS3各自与NS4A结合，在CSFV生命周期中具有独立功能。
