Suppression of pseudorabies virus replication by a mutant form of immediate-early protein IE180 repressing the viral gene transcription.

A mutant form of the immediate-early (IE) protein IE180 of pseudorabies virus (PRV), dIN454-C1081 is a strong repressor of the PRV IE gene promoter. In order to assess the antiviral potential of the IE180 mutant, HeLa cells were transformed with the mutant gene and then infected with PRV and herpes simplex virus type 1 (HSV-1). The transformed cell lines showed marked resistance to PRV infection, but were susceptible to infection with HSV-1, indicating that the IE180 mutant expressed in the stable cell line specifically inhibited PRV growth. In those cells infected with PRV, transcription of the PRV IE gene was repressed. In addition, the IE180 mutant exhibited a dominant-negative property in transient expression assay. The present results indicate that the resistance of the cells to PRV infection was due to repression of the IE gene transcription by the IE 180 mutant.