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Deletion of the us7 and us8 genes of pseudorabies virus exerts a differential effect on the expression of early and late viral genes

Póka, Nándor, Csabai, Zsolt, Pásti, Emese, Tombácz, Dóra, Boldogkői, Zsolt
Virus genes 2017 v.53 no.4 pp. 603-612
DNA replication, Suid herpesvirus 1, gene expression regulation, genes, glycoproteins, membrane proteins, mutants, quantitative polymerase chain reaction, swine, tissue culture, transcription (genetics), transcriptome, viruses
The pseudorabies virus (PRV; also known as Suid herpesvirus-1) is a neurotropic herpesvirus of swine. The us7 and us8 genes of this virus encode the glycoprotein I and E membrane proteins that form a heterodimer that is known to control cell-to-cell spread in tissue culture and in animals. In this study, we investigated the effect of the deletion of the PRV us7 and us8 genes on the genome-wide transcription and DNA replication using a multi-time-point quantitative reverse transcriptase-based real-time PCR technique. Abrogation of the us7/8 gene function was found to exert a drastic but differential effect on the expression of PRV genes during lytic infection. In the mutant virus, all kinetic classes of viral genes were significantly down-regulated at the first 6 h of infection, while having been upregulated later. The level of upregulation was the highest in the immediate-early (IE) and the early (E) genes; lower in the early-late (E/L) genes; and the lowest in the late (L) genes. The relative contribution of the L transcripts to the global transcriptome became lower, while the rest of the transcripts were expressed at a higher level in the mutant than in the wild-type virus.