Varicella-zoster virus (VZV) is an alphaherpesvirus that causes varicella and herpes zoster. In these experiments, cDNA corresponding to 69 VZV open reading frames was added to 42K human cDNA microarrays and used to examine viral as well as cellular gene transcription concurrently in fibroblasts infected with two genetically distinct small plaque VZV mutants, rOka/ORF63rev[T171] and rOkaDeltagI. rOka/ORF63rev[T171] has a point mutation in ORF63, which encodes the immediate early regulatory protein, IE63, and rOkaDeltagI has a deletion of ORF67, encoding glycoprotein I (gI). rOka/ORF63rev[T171] was deficient in the transcription of several viral genes compared to the recombinant rOka control virus. Deletion of ORF67 had minimal effects on viral gene transcription. Effects of rOka/ORF63rev[T171] and rOkaDeltagI on host cell gene transcription were similar to the rOka control, but a few host cell genes were regulated differently in rOkaDeltagI-infected cells. Infection of fibroblasts with intact or small plaque VZV mutants was associated with down-regulation of NF-kappaB and interferon responsive genes, down-regulation of TGF-beta responsive genes accompanied by reduced amounts of fibrotic/wound healing response genes (e.g. collagens, follistatin) and activation of cellular proliferation genes, and alteration of neuronal growth markers, as well as cellular genes encoding proteins important in protein and vesicle trafficking. These observations suggest that replication of VZV small plaque mutant viruses and intact VZV have similar consequences for host cell gene transcription in infected cells, and that the small plaque phenotype in these mutants reflects deficiencies in viral gene expression.
By Jeremy O Jones & Ann M Arvin