Portland State University. Department of Biology.
Robert L. Michelle
Date of Award
Master of Science (M.S.) in Biology
1 online resource (2, v, 64 p.)
Herpes simplex, Genetic transcription -- Regulation
Herpes simplex virus type 1 (HSV-1) is a virus commonly causing cold sores in humans, however, virulent infections are known to produce debilitating encephalitis and death. HSV-1 transcription is carried out by the host cell RNA polymerase II in a tightly regulated temporal cascade. The first genes transcribed, the a genes, are activated in the absence of viral DNA synthesis. Transcription of the other temporal classes, the β, βγ, and γ genes is dependent upon the protein products of the a genes for activation. The purpose of this study was to investigate the factors that contribute to this rigid regulation of HSV-1 transcription. This investigation sought to identify some of the cellular and viral transcription factors that activate transcription of genes of the later kinetic classes. Two separate approaches were utilized in these investigations. 1) In vitro transcription using a soluble, cell free system to study the transcriptional regulation of the VP5 gene, and 2) DNA competition binding assays to identify and characterize the protein-DNA complexes resulting from interaction between the cisacting DNA sequences of the VP5 gene, other viral genes, and the proteins that bind to them. Attempts at in vitro transcription of β, βγ, and γ genes were unsuccessful. Because these genes require a products for activation, it was necessary to prepare nuclear extracts from infected cells. However, HSV-1 contains endogenous RNase activities which are components of the biochemical machinery by which the virus directs host transcription to the synthesis of viral molecules. The uses of virus deficient in the host shut-off function and various drugs were unsuccessful. Previous work in the Millette laboratory demonstrated a sequence in the VP5 promoter that played a significant role in the up regulation of expression of that gene. DNA binding competition studies using a number of HSV-1 sequences exhibiting partial homology to this sequence demonstrated that these sequences all compete for the binding of the same protein factor. Similarly, a piece of the human immunodeficiency virus (HIV) exhibiting a seven base pair homology also exhibited weak competition.
Lown, Rosemary Ann, "Investigations of Factors Affecting the Transcriptional Regulation of Herpes Simplex Virus Type 1 βγ (Leaky-Late) Genes" (1994). Dissertations and Theses. Paper 4855.