Structure and function of Hepatitis C Virus glycoproteins

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Hepatitis C Virus infects approximately 200 million people world-wide and is the major cause of liver transplantation in the Western world. At present there is no vaccine and interferon alpha is the only therapy available and has only limited success in clearing viral infection. HCV is distantly related to flaviviruses eg tick-borne encephaltitis virus and yellow fever virus. All viruses attach to target cells using receptors to initiate the infection process. In the case of HCV, the envelope glycoproteins interact with as yet unknown receptors on the target cell surface resulting in the virus being internalized into endosomes. It is believed that the low pH environment of these endosomes triggers fusion of the viral and cellular membranes. After fusion the genome of the virus is released into target cells and begins the replication process. The actual events intitiating these processes are not understood for HCV but are believed to be mediated using two envelope glycoproteins. In this project we seek to gain a greater understanding of how viral fusion and entry occurs. We have new information regarding the localisation of the two envelope glycoproteins that will now enable us to carefully examine how viral fusion occurs. Using biochemical approaches, we will study their structure and function and examine how this relates to the well understood flavivirus mode of fusion and entry. We will test the functional consequences of altering the structure of the HCV envelope glycoproteins by developing in vitro assays of HCV fusion. Assays for HCV fusion are essential for future studies to identify viral receptors, examine the role of antibody in viral neutralization and can be used to test novel inhibitors of viral fusion and entry.