Several members of the Flaviviridae family are major pathogens of humans including dengue (DEN), yellow fever (YF), tick-borne encephalitis (TBE), Murray valley encephalitis (MVE), Japanese encephalitis (JE), and hepatitis C virus (HCV). An Australian flavivirus Kunjin (KUN), however, appears to be naturally attenuated and does not cause an overt disease in humans. In contrast, genetically and antigenically closely related to KUN, New York strain of West Nile virus (NY WN) has already caused ~50 ....Several members of the Flaviviridae family are major pathogens of humans including dengue (DEN), yellow fever (YF), tick-borne encephalitis (TBE), Murray valley encephalitis (MVE), Japanese encephalitis (JE), and hepatitis C virus (HCV). An Australian flavivirus Kunjin (KUN), however, appears to be naturally attenuated and does not cause an overt disease in humans. In contrast, genetically and antigenically closely related to KUN, New York strain of West Nile virus (NY WN) has already caused ~500 deaths and over 20,000 registered infections since its emergence in North America in 1999, including 223 deaths and 9122 infections in 2003 alone. Recent studies with DEN indicated that flaviviruses may interfere with early steps of IFN-signalling pathway. The type I Interferon (IFN) response is the first line of defence against viral infections and many viruses have developed different strategies to counteract this response in order to ensure their survival in the infected host. In this grant we seek to exploit our extensive understanding of the molecular biology of KUN virus and the contrasting behaviour of KUN and NY WN viruses to gain an understanding of the role of flavivirus-mediated suppression of host anti-viral IFN response in virus-host relationships and its importance in determining virus virulence.Read moreRead less
Cellular Microenvironments Facilitating The Replication And Propagation Of Flaviviruses
Funder
National Health and Medical Research Council
Funding Amount
$505,279.00
Summary
Flaviviruses are the agents of many mosquito-transmitted infections and many deaths globally each year. The emerging virus West Nile virus (strain New York) is a member of this virus family and shares 99% amino acid homology with the endemic Australian virus Kunjin virus. During virus growth in cells, cellular membrane structures are induced or rearranged by these viruses for their own purpose. That being the production of more virus particles for reinfection of other cells. Using Kunjin virus a ....Flaviviruses are the agents of many mosquito-transmitted infections and many deaths globally each year. The emerging virus West Nile virus (strain New York) is a member of this virus family and shares 99% amino acid homology with the endemic Australian virus Kunjin virus. During virus growth in cells, cellular membrane structures are induced or rearranged by these viruses for their own purpose. That being the production of more virus particles for reinfection of other cells. Using Kunjin virus as a model, and advanced techniques in biochemistry and electron microscopy, we have identified for the first time these membrane structures as the apparent sites of replication of the viral RNA or genetic material, and of the viral proteins involved. We have also observed how new virus particles are able to get out of infected cells and shown how some drugs can prevent this occurring thus limiting their transmission. This research will focus on how the membrane structures are formed in infected cells. The research will determine what cellular components are required by the virus to help it propagate. In particular specific cellular proteins and membrane components that are captured by the virus and moved to different sites in the infected cells. These apparent requirements could possibly lead us to a greater understanding of the complex interactions that occur between the invading virus and the host cells. We aim to directly visualize the process of infection within living cells using new and innovative microscopic techniques. Another of our objectives is to determine the effects of infection on normal cells. The question being whether flavivirus infection disrupts normalcell fuctions like secretion etc. An understanding of these processes, and how the viral RNA is copied into new RNA for more virus particles, will assist in the development of antiviral drugs for treatment of this pathogenic group of viruses.Read moreRead less
We seek to gain a detailed understanding of how interactions between the West Nile virus proteins and host factors involved in the IFN response determine the outcome of virus infection. Better understanding of the mechanisms employed by this highly pathogenic virus to disable the mammalian host's IFN response will have wider implications for our understanding of other human diseases such as cancer, autoimmunity and provide new avenues for design of efficient antiviral and anticancer therapies.
Roles Of Virus-integrin Interactions And Rotavirus Modulation Of Host Cell Responses In Viral Pathogenesis
Funder
National Health and Medical Research Council
Funding Amount
$474,000.00
Summary
Rotaviruses are the main cause of severe gastroenteritis in children, and cause 1 in 27 Australian children under the age of 5 years to spend time in hospital. There is currently no rotavirus vaccine available. We aim to discover how rotavirus interacts with host cells. This information is necessary to formulate a safe and effective vaccine, or a therapeutic agent that can block virus growth in host cells. Previously, we showed that rotavirus attaches to cells and enters them using several membe ....Rotaviruses are the main cause of severe gastroenteritis in children, and cause 1 in 27 Australian children under the age of 5 years to spend time in hospital. There is currently no rotavirus vaccine available. We aim to discover how rotavirus interacts with host cells. This information is necessary to formulate a safe and effective vaccine, or a therapeutic agent that can block virus growth in host cells. Previously, we showed that rotavirus attaches to cells and enters them using several members of the integrin protein family that are present on the surface of the cells. Integrins are critical for cell adhesion, survival and communication. In this project, we will identify how rotavirus usage of integrins modulates cell functions. This will help us understand how rotavirus causes disease, how virus spreads in the body and how the immune response defends us from rotavirus. Rotavirus binds integrins using particular stretches of protein sequence that we have shown are also present in other human viral pathogens that cause hepatitis, AIDS and measles. We will determine if these other viruses also recognize integrins.Read moreRead less
Modulation Of Apoptosis By Cytomegalovirus: Analysis Of New Mechanisms To Interfere With Cytomegalovirus-induced Disease
Funder
National Health and Medical Research Council
Funding Amount
$697,084.00
Summary
Apoptosis, or programmed cell death is an essential process in developmental and homeostatic control of complex biological systems. In addition to these primary house keeping roles, apoptosis provides a powerful defence mechanism against invading pathogens, such as viruses, since it allows early elimination of infected cells from the host. A basic property of herpesviruses is their ability to establish persistent infection and remain in association with the host for its lifetime. This strongly u ....Apoptosis, or programmed cell death is an essential process in developmental and homeostatic control of complex biological systems. In addition to these primary house keeping roles, apoptosis provides a powerful defence mechanism against invading pathogens, such as viruses, since it allows early elimination of infected cells from the host. A basic property of herpesviruses is their ability to establish persistent infection and remain in association with the host for its lifetime. This strongly underlines their success at reaching an accommodation with the immune system's anti-apoptotic mechanisms. The central hypothesis of this project is that herpesviruses, such as murine and human cytomegalovirus, encode proteins that interfere with cell death pathways thereby circumventing host defence so that viral replication and dissemination can proceed. Thus, the aims are to identify and characterise cytomegalovirus proteins that modulate apoptosis. These studies will improve our understanding of the control of apoptosis during viral infection, especially as caused by cytomegaloviruses. Human cytomegalovirus (HCMV) is a pathogen able to cause significant morbidity and mortality in individuals with immature or compromised immune systems, such as newborns, AIDS patients, transplant recipients and people treated with chemotherapeutic drugs. Hence, the proposed studies will allow the elucidation of molecular mechanisms that may be relevant to the pathogenesis of HCMV in man and will provide insights into the rational design of suitable antiviral drugs and vaccines. Understanding viral mechanisms of host immune evasion continues to improve our understanding of complex cellular pathways. Therefore, given that abnormal regulation of apoptosis is implicated in the development of degenerative conditions, cancer and autoimmune disease, the proposed studies will provide valuable insight towards the development of new therapies for these pathological conditions.Read moreRead less