Antiviral Effect of Lithium Chloride and Diammonium Glycyrrhizinate on Porcine Deltacoronavirus In Vitro

Zhai, Xiaofeng; Wang, Shilei; Zhu, Mengyan; He, Wei; Pan, Zhongzhou; Su, Shuo

The antiviral effects of LiCl and DG occur at the early stage of PDCoV replication. To further illustrate the effect of LiCl and DG on PDCoV infection, we performed time of addition experiments ( Figure 6A ). Therefore, LiCl or DG was added to infected LLC-PK1 cells at different times. In the '0 hpi' experiment, drugs and virus were added together to LLC-PK1 cells for 1 h. The cells were then washed, and the incubation was continued in the presence of the drugs. In the other experiments, LLC-PK1 cells were infected with PDCoV for 1 h, the cells were then washed, and the drugs were added at 1, 3, 6, 9, 12, 16, and 20 hpi. In all experiments, the cells were infected with PDCoV [ multiplicity of infection (MOI) = 0.05], and 60 mM LiCl or 1250 μg/mL DG was added. The viral contents were significantly reduced in cells treated with LiCl at 0 to 16 h, but no significant reduction was detected after 16 h ( Figure 6B ). For DG, the latest effective time point of drug treatment was 12 hpi ( Figure 6C ). Therefore, we can conclude that the antiviral effects of LiCl and DG occur at the early stages of PDCoV replication.