In vitro antiviral activity and underlying molecular mechanisms of dipotassium glycyrrhetate against porcine reproductive and respiratory syndrome virus.

BACKGROUND: Porcine reproductive and respiratory syndrome virus (PRRSV) has caused large economic losses in the swine industry. Currently, there is no effective way to prevent PRRSV infection. In this study, we investigated the inhibitory effect of dipotassium glycyrrhetate (DG), a derivative of glycyrrhetinic acid, on PRRSV infection ability. METHODS: The cytotoxicity of DG was measured by MTT assay, and the effects of DG on PRRSV N gene/protein were investigated using real-time PCR, western blot and immunofluorescence assay. In addition, the effect of DG on cell apoptosis was analysed by fluorescence staining. RESULTS: Our results indicated that DG could effectively inhibit virus replication and N gene expression in MARC-145 cells infected with PRRSV. When the infected cells received DG, the numbers of apoptotic cells were decreased, and the cleaved caspase-3 contents were decreased dramatically. CONCLUSIONS: Our study demonstrates that DG could effectively inhibit the PRRS virus via multiple pathways including inhibition of virus replication and N gene expression and reduction of apoptotic cells. DG can serve as a potential chemical for PRRSV prevention and control.

Effects of sodium tanshinone IIA sulfonate against Marek's disease virus in experimentally infected chickens.

Chickens experimentally infected with Marek's disease virus J-1 strain were used to evaluate the anti-Marek's disease virus (MDV) activity of sodium tanshinone IIA sulfonate (STS) in vivo. Chickens in same group were kept in one pen and control group chickens were housed in negative pressure isolator. Chickens were treated with different dose of STS or ABOB for 21 consecutive days. Peripheral T lymphocyte proliferation, expression level of IFN-γ and IL-10 in serum, and MDV load in spleen were determined. The results showed that the treatments with STS and ABOB could significantly increase stimulating index (SI) of peripheral T lymphocytes while the SI is dropping due to the MDV infection, SI of chickens in STS prevention groups were significantly higher than that in STS treatment group and ABOB group (P<0.05 or P<0.01); IFN-γ and IL-10 level of chickens in STS groups were higher than that in other groups (P<0.05 or P<0.01). The results of qPCR demonstrated that STS could inhibit the virus replication in spleen of chickens infected with MDV. These findings indicated that STS can be potentially applied as an anti-MDV drug and set a solid basis for further investigating the antiviral mechanisms of STS.