Antiviral activity of Astragalus Polysacharin against PRRSV infection in vitro

Abstract

Abstract Porcine reproductive and respiratory syndrome virus (PRRSV) is the major respiratory difficulties and reproductive disorders-related virus that greatly threats global swine industry, while the commercial vaccines can not provide complete protection against PRRSV infection, and the promising anti-PRRSV drugs are not available. In this study, a PRRSV strain (namely HeN-ZZ) was successfully isolated from the lung sample in a PRRSV-positive farm, and its genetic and biological characteristics were analyzed. Moreover, the effects of Astragalus Polysacharin (APS) on PRRSV infection in marc-145 cells were investigated. The results showed that the viral titer of HeN-ZZ strain proliferated in marc-145 cells reached to 106.56 TCID50/mL, further molecular analysis based on the complete genome showed that HeN-ZZ strain belonged to the sublineage 8.7 (HP-PRRSV) and which was a recombinant between the sublineage 8.7 (JXA1-like) and lineage 5 (VR2232-like) strains. Using HeN-ZZ strain as a model, the results demonstrated that APS displayed efficient antiviral activities against PRRSV infection in a dose manner, with a 50% effective concentration of 2.5 µg/mL. ASP treatment inhibited the expression of viral N gene and reduced progeny virus production, mainly via suppressing viral entry and replication stages. Furthermore, ASP treatment significantly alleviated the inflammatory responses induced by PRRSV infection, suggested that ASP inhibited PRRSV infection in vitro via reducing virus -induced inflammation. These findings indicate that ASP has the potential to be used as a compound for PRRS treatment, while further animal experiments are needed to confirm its anti-PRRSV activity.