The HIV-1 Tat Protein Is An Reverse Transcription Co-factor.
Funder
National Health and Medical Research Council
Funding Amount
$404,592.00
Summary
HIV-1 is the virus that causes AIDS. In order for HIV-1 to grow, the viral genetic material must be converted into a form that is compatible with a human host. Specifically, the HIV-1 genetic material is made of RNA while the human genome is composed of DNA. An HIV-1 enzyme called reverse transcriptase (RT) is used for this purpose. We have discovered that another HIV-1 protein called Tat is also required for the efficient conversion of HIV-1 RNA into HIV-1 DNA. If HIV-1 lacks Tat, then this tra ....HIV-1 is the virus that causes AIDS. In order for HIV-1 to grow, the viral genetic material must be converted into a form that is compatible with a human host. Specifically, the HIV-1 genetic material is made of RNA while the human genome is composed of DNA. An HIV-1 enzyme called reverse transcriptase (RT) is used for this purpose. We have discovered that another HIV-1 protein called Tat is also required for the efficient conversion of HIV-1 RNA into HIV-1 DNA. If HIV-1 lacks Tat, then this transformation process is inefficient and HIV-1 is not able to grow. Recently our group made a breakthrough discovery on how Tat works. Tat can directly bind to RT and stimulate the conversion process. This research is aimed at a detailed analysis of Tat and RT interaction. This information is required in order to understand how this interaction can be blocked in order to stop HIV-1 growth. In the long-term, results produced by this research will be required to discover novel drugs to combat HIV-AIDS.Read moreRead less
The occcurence of herpes simplex virus (HSV) in the general population is very high (up to 60%). In Central Africa, co-infection of HSV and HIV may increase HIV transmission in more than 40% of cases. HSV enters the human body via the skin before entering the termini of nerve cell processes. It is transported along these processes to the body of the nerve cell. HSV lies dormant within these nerve cell bodies near the spinal cord in most people. Intermittently the virus reactivates and is transpo ....The occcurence of herpes simplex virus (HSV) in the general population is very high (up to 60%). In Central Africa, co-infection of HSV and HIV may increase HIV transmission in more than 40% of cases. HSV enters the human body via the skin before entering the termini of nerve cell processes. It is transported along these processes to the body of the nerve cell. HSV lies dormant within these nerve cell bodies near the spinal cord in most people. Intermittently the virus reactivates and is transported back down the nerve cell processes to the skin where it causes blisters-ulcers or is shed without causing symptoms. The aim of this project is to determine how HSV is assembled within cells at the molecular level. This will lead to identification of crucial molecular interactions required for viral assembly. Such information on viral assembly will allow development of inhibitors of this process which may be candidates for use as antivirals for control of recurrent herpes simplex. These antiviral agents will be able to target key viral molecular interactions in essentially all types of cells in the body and act against other herpesviruses in general.Read moreRead less
Worldwide there are approximately 40 million people living with HIV-AIDS. An effective HIV vaccine does not exist at present. Therefore, current strategies to control the HIV pandemic include the use of life saving antiretroviral drugs. While the current drugs are successful in controlling infections, new and more effective agents are needed that inhibit HIV replication by distinct mechanisms due to the inevitable development of drug resistant strains of HIV. The HIV reverse transcriptase enzyme ....Worldwide there are approximately 40 million people living with HIV-AIDS. An effective HIV vaccine does not exist at present. Therefore, current strategies to control the HIV pandemic include the use of life saving antiretroviral drugs. While the current drugs are successful in controlling infections, new and more effective agents are needed that inhibit HIV replication by distinct mechanisms due to the inevitable development of drug resistant strains of HIV. The HIV reverse transcriptase enzyme is essential for HIV replication and has been a successful target for nucleoside reverse transcriptase inhibitors (NRTIs) and nonnucleoside reverse transcriptase inhibitors (NNRTIs). NNRTIs act in part by stabilizing the reverse transcriptase enzyme, thus blocking enzyme function. However, no drugs have been developed that can specifically prevent formation of the reverse transcriptase enzyme, which would result in the production of noninfectious viral particles. We propose that formation of the active reverse transcriptase enzyme, from a large polyprotein called Gag-Pol, proceeds through a homodimer intermediate, which represents an ideal target for blocking reverse transcriptase formation in HIV infected cells. This homodimer intermediate is an attractive target with greater potential for disruption with small molecule inhibitors compared to the mature reverse transcriptase enzyme as it is less stable than the reverse transcriptase found in viruses. This study will determine whether formation of the active RT enzyme is dependent on this intermediate. In addition, we will examine how the reverse transcriptase encoded on Gag-Pol regulates activation of the HIV protease, which is also critical for the formation of infectious virus particles. These studies will increase our understanding of how the virus produces infectious particles and will identify new approaches for targeting the HIV reverse transcriptase enzyme.Read moreRead less
Transport And Egress Of Herpes Simplex Virus In Neurones
Funder
National Health and Medical Research Council
Funding Amount
$592,023.00
Summary
Herpes simplex virus (HSV) enters the human body via the skin before entering the termini of nerve cell processes. It is transported along these processes to the body of the nerve cell. HSV lies dormant within these nerve cell bodies near the spinal cord in most people. Intermittently the virus reactivates and is transported back down the nerve cell processes to the skin where it causes blisters-ulcers or is shed without causing symptoms. The aim of this grant is to determine how HSV is transpor ....Herpes simplex virus (HSV) enters the human body via the skin before entering the termini of nerve cell processes. It is transported along these processes to the body of the nerve cell. HSV lies dormant within these nerve cell bodies near the spinal cord in most people. Intermittently the virus reactivates and is transported back down the nerve cell processes to the skin where it causes blisters-ulcers or is shed without causing symptoms. The aim of this grant is to determine how HSV is transported within nerve cells at the molecular level. Recent discoveries have shown how virus transport in nerve cells is dependent on interactions between specific viral proteins and cellular motor proteins and how the virus escapes from nerves to infect skin and cause disease. Such information on viral transport will allow development of inhibitors of this process which may be candidates for use as antivirals for control of recurrent herpes simplex. In addition, this information will allow the virus to be exploited for use in gene therapy to introduce DNA into human nerve cells to correct genetic abnormalities. Finally this data will assist in understanding similar mechanisms for other viruses transported in nerve cells such as those causing shingles and rabies.Read moreRead less
Both human and viral genetic materials (ribonucleic acids, RNA) are made up of 4 different basic residues, namely A, U, G and C. Combination of any three of these ribonucleic acids residues is known as codon , which is essential to target one of the twenty amino acids to the host cell machinery for the making of proteins. Eighteen out of these twenty amino acids can be represented by more than one codon during the making of proteins. Interestingly, human and viral proteins, such as HIV-1, utilis ....Both human and viral genetic materials (ribonucleic acids, RNA) are made up of 4 different basic residues, namely A, U, G and C. Combination of any three of these ribonucleic acids residues is known as codon , which is essential to target one of the twenty amino acids to the host cell machinery for the making of proteins. Eighteen out of these twenty amino acids can be represented by more than one codon during the making of proteins. Interestingly, human and viral proteins, such as HIV-1, utilise two completely different subsets of codons (codon bias) for the synthesis of their respective proteins. The objective of this proposal is to delineate the functional requirement of this codon bias in HIV-1 replication cycle. Results from this work will identify novel elements that may be used for the design of novel antiretroviral strategy. Furthermore, lesson learned from this project will also provide important clues to improve the efficacy and safety of the design of current retroviral gene delivery vector.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
Structure And Function Of The Hepatitis C Virus Glycoproteins E1 And E2.
Funder
National Health and Medical Research Council
Funding Amount
$533,828.00
Summary
Hepatitis C virus (HCV) infects approximately 3 % of the global human population with 150,000-200,000 HCV-infected individuals currently living in Australia. Chronic HCV infection is associated with recurrent, progressively worsening liver disease, liver cirrhosis and hepatocellular carcinoma. The current therapy (interferon-ribavirin) is effective in only 40 % of patients and is often associated with severe side-effects. The mechanisms that HCV uses to replicate in liver cells is poorly underst ....Hepatitis C virus (HCV) infects approximately 3 % of the global human population with 150,000-200,000 HCV-infected individuals currently living in Australia. Chronic HCV infection is associated with recurrent, progressively worsening liver disease, liver cirrhosis and hepatocellular carcinoma. The current therapy (interferon-ribavirin) is effective in only 40 % of patients and is often associated with severe side-effects. The mechanisms that HCV uses to replicate in liver cells is poorly understood. In this project we aim to better understand how the viral glycoproteins, E1 and E2, function in the initiation of infection. In particular, we will examine how these glycoproteins bind to liver cell receptors and then mediate virus-cell membrane fusion. These processes lead to the penetration of the HCV genetic material into the cell where it is replicated. These studies are essential for the discovery of new targets for antiviral agents and vaccines.Read moreRead less
Determination Of The Mechanisms Of Action Of A Cytomegalovirus Chemokine Receptor Homologue In Pathogenesis
Funder
National Health and Medical Research Council
Funding Amount
$251,341.00
Summary
A number of herpesviruses encode proteins that are similar to proteins of our immune system. These pirated proteins are exploited by the virus to enable it to replicate and persist in the infected individual, usually by evading or gaining advantage from the normal immune response. This project will investigate the role of one such protein found in both human and animal herpesviruses (specifically cytomegaloviruses (CMV)) that is conserved with cellular cell surface proteins (receptors) that bind ....A number of herpesviruses encode proteins that are similar to proteins of our immune system. These pirated proteins are exploited by the virus to enable it to replicate and persist in the infected individual, usually by evading or gaining advantage from the normal immune response. This project will investigate the role of one such protein found in both human and animal herpesviruses (specifically cytomegaloviruses (CMV)) that is conserved with cellular cell surface proteins (receptors) that bind immune signaling molecules (chemokines). Chemokines are important proteins in the early response to infection. Binding of chemokines to their receptors initiates a cascade of signals within the cell that has profound effects on cellular responses to environmental stimuli. Thus, it is believed that herpesviruses have acquired chemokine receptors to modify or react to the immune response, causing infected cells to behave abnormally either despite or in response to chemokine signals. This project will determine how this CMV specific protein affects the function of cells that CMV infects and how this may promote virus replication, dissemination and persistence in infected hosts. We will also engineer CMVs where the activity of the target protein can be inhibited by administration of prototype antiviral drugs. If inhibition of the activity of the protein is found to reduce virus replication, dissemination or persistence, then this will demonstrate that this type of protein would be a suitable target for the development of novel drugs active against CMV infections. CMV can cause serious (potentially life threatening) disease in newborn children (following infection in the uterus) and immunosuppressed people (eg. organ transplant recipients and people with HIV-AIDS). Our studies will improve our understanding of the contribution of a specific CMV protein to disease, thereby assisting efforts to reduce the impact of CMV infections.Read moreRead less