Synergistic inhibition of pseudorabies virus replication by porcine alpha/beta interferon and gamma interferon in vitro.

Yao, Qingxia; Qian, Ping; Cao, Yi; He, Yannan; Si, Youhui; Xu, Zhuofei; Chen, Huanchun

Interferon (IFN) is crucial for initiating the innate immune response and for the generation of the adaptive response. IFN, in most species, comprises IFN-alpha (IFN-alpha), IFN-beta (IFN-beta) and IFN-gamma (IFN-gamma). In this study, we compared the capacity of porcine IFN-alpha, -beta and -gamma, or a combination of them, to protect IBRS-2 cells (porcine kidney cells) from infection with pseudorabies virus (PRV). The results demonstrated that porcine IFN-beta (PoIFN-beta) was the most efficient of the three IFNs in conferring resistance PRV infection; 100 U/mL PoIFN-beta inhibited PRV plaque formation 5.3-fold. Compared with PoIFN-beta, porcine IFN-gamma (PoIFN-gamma) was less capable of inhibiting PRV plaque formation (3.3-fold inhibition). Porcine IFN-alpha (PoIFN-alpha) had the least capability of the three PoIFNs, and inhibited PRV plaque formation only 1.26-fold. The inhibitory capacity increased to only 2.3-fold with a treatment of 12,800 U/mL PoIFN-alpha. A combination of PoIFN-gamma and PoIFN-alpha or PoIFN-beta inhibited PRV plaque formation 12.8-fold or 100-fold, respectively. Treatment of IBRS-2 cells with PoIFN-alpha/beta and PoIFN-gamma inhibited PRV replication 29- or 146-fold. Additionally, real-time PCR analyses of the PRV immediate early (IE) gene revealed that IE mRNA expression was profoundly decreased in cells stimulated with PoIFN-alpha/beta and PoIFN-gamma (23.8-133.0-fold) compared with vehicle-treated cells. All the findings indicate that PoIFN-gamma acts synergistically with other PoIFNs (PoIFN-alpha and -beta) to potently inhibit PRV replication in vitro.