Structure function analysis of the Dengue virus capsid protein.

Dengue is the most important mosquito-borne viral disease of humans with 50-100 million people infected annually worldwide. Dengue virus infection usually results in dengue fever, a mild ?flu? like illness. However, in some cases, patients may develop severe, potentially fatal complications known as dengue haemorrhagic fever/dengue shock syndrome (DHF/DSS). Despite intensive research over recent years, the disease processes leading to DHF/DSS are still poorly understood and there is neither a safe and effective vaccine nor suitable anti-viral treatments to control dengue disease.

This project aims to study the function/s of the dengue virus capsid protein in the virus lifecycle and its possible contribution to disease processes. Dengue virus particles consist of multiple copies of only three proteins. A lipid membrane containing two surface proteins surrounds an inner core consisting of the capsid protein and the viral RNA genome. Aside from its role in the formation of the virus particle, the capsid protein has also been found in the host cell nucleus where it has the potential to disturb host cell processes. We will use recent information about the three dimensional structure of the capsid protein, in combination with genetic engineering of the viral genome, to identify regions of the capsid protein essential to the virus lifecycle. By determining how these regions of the C protein function in the virus lifecycle, we will increase our understanding of dengue virus replication and disease, and provide knowledge that can be used to develop novel dengue vaccines and antiviral compounds. The results of this investigation will also be relevant to related flaviviruses such as West Nile virus, Yellow fever virus and tick-borne and Japanese encephalitis viruses which cause public health problems worldwide.

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Dengue virus (DENV) is a mosquito borne flavivirus infecting 50-100 million individuals annually worldwide. Dengue disease ranges from mild fever to the potentially fatal dengue haemorrhagic fever/ shock syndromes. Despite intensive research over recent years, the pathogenesis of DHF/DSS is still poorly understood and there is neither a safe and effective vaccine nor suitable anti-viral treatments to control dengue disease. The DENV particle contains an RNA genome and three structural proteins (capsid, membrane and envelope). The capsid (C) protein plays an essential role in the virus structure, surrounding the genome to form the virus nucleocapsid. Moreover, although the DENV C protein is initially ER membrane associated, it also localises to the nucleus and evidence suggests that the DENV C protein interacts with and modulates the function of host cell factors. During 2004, detailed NMR and X-ray structural data has become available for the C protein, however the molecular determinants that govern the function of the C protein in the viral life cycle are largely unresolved. Recent studies have shown that flaviviruses containing engineered deletions in the C gene are attenuated and potentially novel and attractive candidates for the development of flavivirus vaccines. This proposal aims to use reverse genetics, in combination with recent C protein structural data, to identify specific regions and residues in the DENV C protein that interact with cellular and viral components. Furthermore, we will analyse how these interactions regulate viral replication and morphogenesis. By determining how specific regions of the C protein function in the virus lifecycle, we will increase our understanding of flavivirus replication and pathogenesis, and provide knowledge that can be used to develop novel dengue vaccines and antiviral compounds.