Inhibition of porcine hemagglutinating encephalomyelitis virus replication by short hairpin RNAs targeting of the nucleocapsid gene in a porcine kidney cell line.

Porcine hemagglutinating encephalomyelitis virus (PHEV), which causes porcine encephalomyelitis and is widespread among swine worldwide. RNA interference (RNAi) pathways have emerged as important regulators of virus-host cell interactions. In this study, two siRNA expression plasmids (shN1 and shN2) were generated to target two different coding regions of the nucleocapsid protein (N) of PHEV. The shRNAs were transiently transfected into a porcine kidney cell line, PK-15, to determine whether these constructs inhibited PHEV production. Our results revealed that both shRNAs were highly capable of inhibiting viral RNA genome replication, especially shN2. Next, stable transfection of shN2 was used to produce two siRNA stably expressing PK-15 cell clones (shN2-1 and shN2-2), and these two lines were infected with PHEV. The analysis of cytopathic effects (CPE) demonstrated that shN2-1 and shN2-2 were capable of protecting cells against PHEV infection with high specificity and efficiency. Furthermore, effective inhibition of viral replication persisted for up to 120 h by a TCID(50) assay. These results indicated that RNAi targeting of the N gene could facilitate studies of the specific function of viral genes associated with PHEV replication and may have potential therapeutic applications.