Cinnamaldehyde Inhibits the Replication of Porcine Reproductive and Respiratory Syndrome Virus Type 2 In Vitro.

Globally, the swine industry suffers significant economic losses due to the presence of porcine reproductive and respiratory syndrome virus (PRRSV). Unfortunately, existing vaccines fail to offer adequate protection against the various strains of PRRSV, and there are currently no specific treatments available for this virus. In this study, we screened four natural products and identified cinnamaldehyde (CA) as an effective inhibitor of PRRSV infection in Marc-145 cells. CA could achieve an inhibition rate of up to 93% on PRRSV N protein at 160 μM. Mechanistically, CA exerted anti-PRRSV ability in different treatment modes. CA could directly interact with PRRSV particles. Cinnamaldehyde blocks the binding, entry, replication, and release of PRRSV. Furthermore, a significant reduction in dsRNA levels was observed in the CA-treated groups compared to the control groups. In conclusion, our research demonstrated that CA could inhibit essential stages of the PRRSV lifecycle: binding, entry, replication, and release. CA could directly interact with PRRSV. Additionally, CA disrupted the expression of dsRNA during viral replication, thereby suppressing in vitro PRRSV replication in Marc-145 cells. This study provides crucial perspectives on the potential application of CA for the prevention and treatment of PRRS.