Open reading frames 1a and 1b of the porcine reproductive and respiratory syndrome virus (PRRSV) collaboratively initiate viral minus-strand RNA synthesis

• DOI: 10.1016/j.bbrc.2016.06.161
• Publication Date: 2016-07-03T08:48:02Z
• Authors: Yan-Dong Tang; Qiong-Qiong Fang; Ji-Ting Liu; Tong-Yun Wang; Yu Wang; Ye Tao; Yong-gang Liu; Xue-Hui Cai
• Keywords: Arterivirus; RNA virus

The porcine reproductive and respiratory syndrome virus (PRRSV) causes a persistent threat to the swine industry, especially when highly pathogenic PRRSV (HP-PRRSV) emerges. Previous studies have indicated that PRRSV RNA synthesis was correlated with HP-PRRSV virulence. PRRSV RNA synthesis includes genomic RNA and sub-genomic mRNA, and these processes require minus-strand RNA as a template. However, the mechanisms involved in PRRSV minus-strand RNA synthesis are not fully understood. A mini-genome system can be used to assess viral replication mechanisms and to evaluate the effects of potential antiviral drugs on viral replicase activities. In this study, we developed a mini-genome system that uses firefly luciferase as a reporter. Based on this system, we found that PRRSV RNA-dependent RNA polymerase nsp9 alone failed to activate virus minus-strand RNA synthesis. We also demonstrated that combinations of open reading frames 1a (ORF1a) and ORF1b are necessary for viral minus-strand RNA synthesis.