Pseudorabies virus (PRV) early protein O activates PRV gene transcription in combination with the immediate early protein IE180 and enhances the infectivity of PRV genomic DNA

Pseudorabies virus (PRV) early protein 0 (EPO) functions as a transactivator of the viral gene promoters. In transient expression assays employing chloramphenicol acetyl transferase (CAT) reporter constructs, EPO and the immediate-early protein IE180 act in an additive manner to activate transcription from the thymidine kinase (TK) and glycoprotein G (gG) gene promoters. EPO enhanced the synthesis of infectious virus in cotransfection experiments with the EPO-expression plasmid and PRV genomic DNA. EPO was detected by Western blot analysis in the purified virions. These results may indicate that EPO in the virions acts as an important transactivator to express the immediate-early gene efficiently in the first stage of infection, and IE180 and EPO expressed after the infection cooperatively activate the early and late gene expression in the later stage of infection. (C) 1998 Elsevier Science B.V. All rights reserved.