3 show that the ZF domain itself could not inhibit the Poly (I:C) or the ectopic expression of VISA-, TRIF-, or IKK-?-induced activation of the promoter (Fig. single positive-strand RNA genome, is a member of family (Cavanagh 1997; Meulenberg 2000). Since it was first identified in the United States in 1987 and in Europe in 1990, PRRSV has caused one of the most economically important diseases of swine that is characterized by severe reproductive failure in sows and respiratory distress in piglets and growing pigs (Rossow 1998). Infection with PRRSV also predisposes pigs to a secondary infection by bacterial and viral pathogens, which may be due to the immunosuppression induced by the virus (Feng and others 2001; Mateu and Diaz 2008). Type I interferon (IFN- and IFN-) is the first responder against animal virus infections (Muller and others 1994; Weber and Saracatinib (AZD0530) others 2004). When a virus infects, the virus could be recognized by the pattern-recognition receptors (PRRs) such as membrane-bound Toll-like receptors (TLRs) (including TLR3, TLR7, TLR8, and TLR9), retinoic-acid-inducible gene I (RIG-I)-like receptors (RLRs) [including the retinoic acid-inducible gene I (failed Saracatinib (AZD0530) to inhibit the induction of IFN- nsp1 contained 3 parts: the N-terminal ZF domain (Met1-Glu65), the PCP domain (PCP domain, Pro66 to Gln166), and the C-terminal extension (CTE; Arg167 to Met180) (Sun and others 2009). Previous Studies have demonstrated that nsp1 inhibited the production of IFN- (Chen and others 2010; Shi and others 2011b). To explore whether the ZF domain was essential for nsp1 as the antagonist to the IFN- production, we deleted the ZF domain in nsp1 and constructed the expression plasmidpcDNA3.1-FLAG nsp1 66C180 (nsp1 DZF)the expressions of which were confirmed by western blot (Fig. 1A), and found that the mutant that deleted the ZF domain in Saracatinib (AZD0530) nsp1 failed to block Poly (I:C)(a synthetic dsRNA analog)-induced activation of the promoter (Fig. 1B). Open in a separate window FIG. 1. The nsp1 mutant that deleted the zinc-finger (ZF) domain failed to inhibit the activities of the interferon (promoter (p-284 Luc) and the pIRF-3-dependent promoter (p55C1B Luc). (A) Western blots analyzed the expression of nsp1 and nsp1 66C180 (nsp1 DZF) by anti-FLAG antibody in MARC-145 cells transfected with pcDNA3.1-FLAG (Vector), pcDNA3.1-FLAG-nsp1 (nsp1), or pcDNA3.1-FLAG-nsp1 66C180 (nsp1 DZF). MARC-145 cells were cotransfected with p-284 Luc (B) or p55C1B Luc (C), phRL-TK, and different expression plasmids. Twenty hours later, cells were either mock-treated (Con) or transfected with poly (I:C) for 6?h, and then the cells were harvested for the dual luciferase reporter assay. MARC-145 cells were cotransfected with p-284 Luc (D) or p55C1B Luc (E), phRL-TK, and different expression plasmids. Twenty-four hours later, the cells were harvested for dual luciferase reporter assay. Tagln Con: cells transfected with pcDNA3.1. nsp1 DZF: deletion of the ZF domain in nsp1. Data represented means of 3 replicates, and experiments were repeated 3 times. Error bars represented the standard deviations. *promoter (Peters and others 2002), p55C1B-Luc (Yoneyama and others 1998, 2004; Devaraj and others 2007), the pIRF-3-dependent synthetic promoter, was detected after the Poly (I:C) treatment or the mock treatment. As shown in Fig. 1C, nsp1 66C180 (nsp1 DZF) could not inhibit the activation of p55C1B-Luc; that is, the results in Fig. 1C confirmed that in Fig. 1B. Poly (I:C), a double-stranded RNA, could be recognized by TLR3 (Yamamoto and others 2003) and MDA5 (Gitlin and others 2006; Kato and others 2006; Onoguchi and others 2011). Then, through TBK1 and IKK-?, TLR3 recruited TRIF, and MDA5 recruited VISA, to phosphorylate IRF-3, and finally activate the promoter (Bowie and Unterholzner 2008). Overexpression of VISA, TRIF, or IKK-? could induce the activation of IRF-3 and activate the promoter (Yoneyama and others 2004; Devaraj and others 2007; Zhong and others 2008). Our previous study has shown that nsp1 inhibited the IFN- production induced by overexpression of VISA, TRIF, or IKK-? (Shi and others 2010, 2011b), so we investigated whether deleting the ZF domain could also influence the nsp1 to inhibit the IFN- production induced by overexpression of VISA, TRIF, or IKK-?. The results showed that the mutation that deleted the ZF domain in nsp1 could not suppress promoter activation induced by ectopic expression of VISA,.