A screening method of anti-aquatic viral drugs based on Nrf2/HO-1 promoter

In order to establish an antiviral drug screening method targeting to Nrf2 / HO-1 pathway, the recombinant plasmids of Nrf2 and HO-1 promoter were constructed, respectively. The effects of different concentrations (0.0, 3.1, 6.3, 12.5, 25.0 and 50.0 μg/mL) of resveratrol, silybin, andrographolide and curcumin on promoter activity were detected by the dual luciferase reporter system in fathead minnow cells (FHM). Further, spring viremia of carp virus (SVCV) and rana grylio iridovirus (RGV) were used to verify the antiviral effect of positive drugs in FHM cells. The results showed that a variety of binding sites for transcription factors were found in the Nrf2 and HO-1 promoter sequences, including FOX family and IRF family. As well, 1 and 3 methylation-related CpG islands were found, respectively. The dual luciferase reporter assay showed that silybin, andrographolide and curcumin could activate the Nrf2 and HO-1 promoters. Drug concentration gradient experiments showed that curcumin and andrographolide at a concentration of 6.3 μg/mL could significantly up-regulate the promoter activities of Nrf2 and HO-1. The cytopathic effect observation, virus replication tests and virus titration assay confirmed that curcumin and andrographolide can inhibit the infection of SVCV and RGV significantly. In conclusion, the pGL3-Nrf2 and pGL3-HO-1 promoter reporter plasmids established in this experiment can be used for the screening of anti-aquatic virus drugs, and also provide tools for the study of the transcriptional regulation mechanism of Nrf2 and HO-1.