Expression

This chapter focuses on the mechanisms by which cells express the information stored in genes, and examines the genome coding struggles of different virus groups. Control of gene expression is a vital element of virus replication. Coordinate expression of groups of virus genes results in successive phases of gene expression. Immediate–early genes encode activator proteins, early genes encode further regulatory proteins, and late genes encode virus structural proteins. Viruses make use of the biochemical apparatus of their host cells to express their genetic information as proteins and, consequently, utilize the appropriate biochemical language recognized by the cell. Thus viruses of prokaryotes produce polycistronic mRNAs, while viruses with eukaryotic hosts produce more monocistronic mRNAs. Some viruses of eukaryotes do produce polycistronic mRNA to assist with the coordinate regulation of multiple genes. Viruses rely on specific cis- and trans-acting mechanisms to manipulate the biology of their host cells, and to enhance and coordinate the expression of their genetic information. The chapter discusses control of prokaryote gene expression, expression in bacteriophage λ, eukaryote gene expression, and also discusses genome coding strategies. The chapter ends with a discussion of the transcription and post-transcriptional methods of control of gene expression.