Saccharicterpenin Exerts Multi-Stage Antiviral Activity Against Pseudorabies Virus In Vitro

Pseudorabies virus (PRV) variants continue to threaten the swine industry because of the limited protection provided by current vaccines. This study evaluated the antiviral activity of Saccharicterpenin (SAC), a plant-derived extract rich in triterpenoid saponins and polysaccharides, against PRV in vitro. At non-cytotoxic concentrations, SAC inhibited PRV replication in a dose-dependent and strain-independent manner (EC50 = 60.12 μg/mL; SI = 3.76), as demonstrated by reduced viral genome copies, infectious titers, viral gene transcription, and protein expression. Mechanistic analyses revealed that SAC exerted multi-stage antiviral actions by directly neutralizing virions, conferring prophylactic protection via decreased cellular susceptibility, impairing viral attachment and internalization processes, reducing extracellular progeny virus yield, and attenuating PRV-induced relative mRNA expression of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, and IL-8). Collectively, these findings demonstrate the multi-stage in vitro antiviral activity of SAC against PRV. Although the in vitro selectivity index is relatively modest, these findings provide preliminary evidence supporting further evaluation, active fraction characterization, and in vivo validation of SAC in veterinary medicine.