Research Abstract

The Coen laboratory takes molecular approaches to herpesviruses, especially to understand processes that distinguish viral functions from cellular functions, which can be exploited to permit antiviral therapy. Although much of the research involves herpes simplex virus (HSV), which is not an oncogenic virus, many of the findings apply to oncogenic herpesviruses and to biological processes and drug discovery strategies relevant to cancer in general.

The foci of the laboratory are 1) regulation of expression of viral genes, 2) functional dissection of replication proteins, 3) analysis of virus latency, a fascinating and clinically important topic, 4) antiviral drug targets, drug mechanisms, and drug resistance. In the first area, we study novel post-transcriptional regulatory mechanisms in the HSV system, including ribosomal frameshifting on thymidine kinase mRNAs from drug-resistant mutants, antisense regulation, and regulated

polyadenylation. In the second area, we focus on herpesvirus DNA polymerases, which are both antiviral drug targets and prototypes for eukaryotic replicative polymerases. We use antiviral drug resistance to help dissect amino acid residues involved in the the different steps of polymerization; explore the interactions of polymerases with processivity proteins via mutational and biophysical approaches; and have been determining how the processivity factors function via a novel mechanism involving direct DNA binding. These studies should permit detailed

understanding of these complicated enzymes and rational drug design, particularly to interrupt protein-protein interactions.

In the third area, latency and pathogenesis, we use virus mutants and PCR-based methods to explore gene function and regulation (e.g. checkpoints for repressing gene expression) and the state of viral DNA during latency. We are also studying the interaction of HSV with the central nervous system with implications for the use of HSV-based therapies for nervous system diseases such as brain tumors. In the fourth area, antiviral drug targets, mechanisms, and resistance, aside from the studies mentioned above, we are exploiting the human cytomegalovirus protein

kinase that phosphorylates ganciclovir to aid the design of better antiviral drugs, and are finding new drug targets primarily by analyzing drug-resistant mutants.