Study on the anti-PRRSV effect of recombinant porcine α interferon

Porcine reproductive and respiratory syndrome virus (PRRSV) causes significant economic losses to the global swine industry. In this study, the inhibitory effect of recombinant porcine interferon alpha (rPoIFN-α) against PRRSV was evaluated using a MARC-145 cell model. Cytotoxicity assays confirmed that rPoIFN-α dilutions that were 100-fold (corresponding to a titer of 2 × 10⁵ IU/mL) greater were nontoxic to MARC-145 cells. Treatment with rPoIFN-α at concentrations of 4 × 10⁴ IU/mL and 2 × 10⁴ IU/mL (corresponding to 500-fold and 1000-fold dilutions, respectively) significantly reduced the PRRSV-induced cytopathic effect (CPE), viral nucleocapsid (N) gene expression, and viral titers (TCID₅₀) compared with those in the infected, untreated controls. Notably, compared with short-term co-incubation during viral adsorption, continuous treatment with rPoIFN-α post-infection was significantly more effective at inhibiting PRRSV. These findings demonstrate that rPoIFN-α possesses potent anti-PRRSV activity in vitro, with prolonged exposure post-infection being the more effective treatment regimen. This study provides a foundational basis for the design of treatment regimens and dose-ranging studies for rPoIFN-α in future in vivo experiments aimed at controlling PRRS.