Dihydromyricetin Inhibits Pseudorabies Virus Multiplication In Vitro by Regulating NF-κB Signaling Pathway and Apoptosis

SIMPLE SUMMARY: Pseudorabies virus (PRV) is a herpesvirus with zoonotic potential and has caused significant economic losses to the global pig industry. With the emergence of new mutants, the immune protection provided by vaccines has been greatly reduced, and it has become more difficulty to control PRV by vaccination. Recently, human cases of PRV-induced encephalitis have been reported, which suggest an urgent need for new control measures. In this study, we found that dihydromyricetin (DMY) exerted potent antiviral activity against PRV in vitro. DMY could ameliorate the PRV-induced abnormal activation of the NF-κB signaling pathway and excessive cellular inflammatory response. DMY could also induce the apoptosis of PRV-infected cells, thereby limiting the production of progeny virus. Based on the findings, DMY could be a candidate drug for the treatment of PRV infections. ABSTRACT: Pseudorabies virus (PRV) infections have caused huge economic losses to the breeding industry worldwide, especially pig husbandry. PRV could threaten human health as an easily ignored zoonotic pathogen. The emergence of new mutants significantly reduced the protective effect of vaccination, indicating an urgent need to develop specific therapeutic drugs for PRV infection. In this study, we found that dihydromyricetin (DMY) could dose-dependently restrain PRV infection in vitro with an IC50 of 161.34 μM; the inhibition rate of DMY at a concentration of 500 μM was 92.16 %. Moreover, the mode of action showed that DMY directly inactivated PRV virion and inhibited viral adsorption and cellular replication. DMY treatment could improve PRV-induced abnormal changes of the NF-κB signaling pathway and excessive inflammatory response through regulation of the contents of IκBα and p-P65/P65 and the transcriptional levels of cytokines (TNF-α, IL-1β and IL-6). Furthermore, DMY promoted the apoptosis of PRV-infected cells through the regulation of the expressions of Bax and Bcl-xl and the transcriptional levels of Caspase-3, Bax, Bcl-2 and Bcl-xl, thereby limiting the production of progeny virus. These findings indicated that DMY could be a candidate drug for the treatment of PRV infection.