AIDS is caused by the human immunodeficiency virus type 1 (HIV-1). Long-term HIV infection leads to increased incidence of Kaposi's sarcoma, AIDS dementia complex, and immune dysfunctions. The HIV-1 Tat protein has been linked to disease progression. However, Tat is predominantly found in the cell nucleus while measurable levels in patient serum. This is not believed to be a passive event caused by dying cells. Here we will investigate how Tat is released by HIV-1 infected cells.
HOST CELL FACTORS INCREASE THE EFFICIENCY OF HIV-1 REVERSE TRANSCRIPTION
Funder
National Health and Medical Research Council
Funding Amount
$636,919.00
Summary
We have found that when human immunodeficiency virus (HIV) infects a cell, it uses functions of the host to better infect. At this point, we do not know the identity of the host cell factors involved. If we are able to identify the factors we might be able to specifically target them without affecting normal cell functions. This approach has the advantage that it minimises the opportunities for the virus to develop drug resitance, which is increasingly a problem with HIV.
The HIV-1 Spacer Peptide P1: A Novel Anti-retroviral Target
Funder
National Health and Medical Research Council
Funding Amount
$384,000.00
Summary
Human immunodeficiency virus type 1 (HIV-1) is the virus that causes AIDS. The treatment that is in current use, called highly active anti-retroviral therapy (HAART), has significantly delayed the onset of AIDS in HIV-1 infected patients. This therapeutic regimen requires the action of three or more drugs to generate a potency that is sufficient to suppress the virus and restrict outgrowth of resistant mutants. However, even on HAART the virus continues to replicate at a low level, and the threa ....Human immunodeficiency virus type 1 (HIV-1) is the virus that causes AIDS. The treatment that is in current use, called highly active anti-retroviral therapy (HAART), has significantly delayed the onset of AIDS in HIV-1 infected patients. This therapeutic regimen requires the action of three or more drugs to generate a potency that is sufficient to suppress the virus and restrict outgrowth of resistant mutants. However, even on HAART the virus continues to replicate at a low level, and the threat of the development of resistant mutations is ever present. Consequently, additional drug targets are required to continue the successful treatment of HIV-1 infected patients. This research is focused on a large polyprotein produced by HIV called Gag. One end of Gag contains a smaller protein called P1 that is crucial for the ability of HIV to reproduce itself. Small changes to the genetic makeup of P1 (one or two amino acids) lead to a defective virus that cannot replicate. The apparent integral role of P1 in viral replication makes it an excellent target for anti-retroviral therapy. With this project we will further our understanding of P1's role in HIV replication and look at ways we target P1 for the development of effective anti-viral agents.Read moreRead less
The Mechanism Of Tat-enhanced Reverse Transcription In HIV-1
Funder
National Health and Medical Research Council
Funding Amount
$282,750.00
Summary
During reverse transcription, the positive-strand HIV-1 RNA genome is converted into a double-stranded DNA copy which can be permanently insert into the host cell genome. Many HIV-1 proteins including Tat contribute to the efficiency of reverse transcription. There are two competing hypotheses to explain how Tat enhances reverse transcription. The indirect mechanism hypothesis holds that Tat-enhanced reverse transcription is due to the combined effects of the Tat-induced expression of cellular g ....During reverse transcription, the positive-strand HIV-1 RNA genome is converted into a double-stranded DNA copy which can be permanently insert into the host cell genome. Many HIV-1 proteins including Tat contribute to the efficiency of reverse transcription. There are two competing hypotheses to explain how Tat enhances reverse transcription. The indirect mechanism hypothesis holds that Tat-enhanced reverse transcription is due to the combined effects of the Tat-induced expression of cellular genes. The direct mechanism hypothesis is that Tat functions directly during RTN, implying it is a virion protein. Our recent genetic and biochemical data provide strong evidence that a novel form of Tat, which we call vTat, has a direct role in RTN. This proposal will investigate these two leading hypotheses. Given the enormity of the HIV pandemic and the many recent reports from the United States that most patient isolated virus is resistant to at least one antiretroviral drug, these studies have as an outcome the identification and characterisation of important new key molecules towards which antiretroviral strategies can be designed.Read moreRead less
Structural And Functional Role Of HIV-1 Gp41 Terminal Interactions In The Membrane Fusion Mechanism
Funder
National Health and Medical Research Council
Funding Amount
$529,632.00
Summary
Approximately 40 million individuals are currently living with HIV. The viral glycoproteins, gp120-gp41, mediate the first stage of infection, membrane fusion, and thus serve as targets for vaccines and antiviral agents. Thi proposal seeks to assess the structure and function of a potential new drug target in gp120-gp41. These studies may lead to the identification of a new antiviral that blocks membrane fusion. Such agents can be added to antiviral drug cocktails for more effective therapy.
Human immunodeficiency virus type 1 (HIV-1) causes AIDS and, to date, has infected approximately 20 thousand people in Australia and more than 40 million worldwide. People infected with HIV-1 first experience a period of 5-7 years where they remain healthy, ofter assisted by the use of anti-HIV-1 drugs, and this period is referred to as the asymptomatic period. After this period, infected individuals become sick due to their immune system being destroyed, and this is referred to as AIDS. Researc ....Human immunodeficiency virus type 1 (HIV-1) causes AIDS and, to date, has infected approximately 20 thousand people in Australia and more than 40 million worldwide. People infected with HIV-1 first experience a period of 5-7 years where they remain healthy, ofter assisted by the use of anti-HIV-1 drugs, and this period is referred to as the asymptomatic period. After this period, infected individuals become sick due to their immune system being destroyed, and this is referred to as AIDS. Research into how HIV-1 causes AIDS has shown us that the virus changes over time to make itself better able to kill cells of the immune system, by at least 2 mechanisms. The first mechanism, which is the best characterised one, is where the virus changes the way it infects cells, whereby it can infect many more cells in the body by taking advantage of an alternate receptor molecule on the cell called CXCR4. This molecule is very widely expressed on immune cells, and thus the virus can now infect and kill many more cells. However, in about 50% of infected people who eventually get AIDS, the virus does not change this way. The virus instead uses it's original receptor to infect cells, called CCR5. Our preliminary studies, as well as other published reports, suggest that the virus changes itself another way to make it kill immune cells better, without using CXCR4. However, the mechanism by which HIV-1 does this is poorly understood. This proposal aims to better understand this mechanism. We expect to find that, in this group of patients, the Env proteins on the virus change to be able to bind CCR5 more tightly, and thus be able to use fewer molecules of CCR5 to infect cells. We believe that these forms of the virus are now better able to kill immune cells, leading to AIDS. This study will contribute to a greater understanding of how HIV-1 causes AIDS, which is necessary for the development of new drugs to treat HIV-1 infection.Read moreRead less
Evolutionary Events Shaping The Genome Of Cryptococcus Neoformans And Their Effects On Pathogenesis
Funder
National Health and Medical Research Council
Funding Amount
$387,489.00
Summary
Recurring infection in patients with fungal meningitis caused by Cryptococcus neoformans is typically caused by persistence of the original infection rather than reinfection with a new strain. Our analysis of relapse strains shows that small-scale alterations frequently occur at the chromosome ends - regions containing important pathogenesis-related genes in other pathogens. We seek to characterise this microevolution further to understand how it contributes to the success of this pathogen.
CHARACTERIZATION AND PURIFICATION OF A NOVEL ANTI-HIV FACTOR
Funder
National Health and Medical Research Council
Funding Amount
$170,810.00
Summary
We have identified biological evidence for a novel anti-HIV factor in a patient who has not progressed to HIV disease in 22 years. We have identified active forms in a solution, which confer potent activity against HIV. This factor helps in creating the pool of specialized antigen presenting cells, which are vital to combating with HIV in vivo. We propose to characterize this factor biologically, proteomically and genomically.
HIV infection of CD4+ lymphocytes leads to a high rate of reproduction of new virus. However, in the brain, HIV infection of the astrocytes does not yield high levels of new virus. HIV is genetically active in these astrocytes, producing high levels of the messenger molecules, the so-called mRNA, that code for the proteins required for a new virus particle. We have determined that these HIV mRNAs are specifically prevented from translating into protein. The mechanisms controlling protein transla ....HIV infection of CD4+ lymphocytes leads to a high rate of reproduction of new virus. However, in the brain, HIV infection of the astrocytes does not yield high levels of new virus. HIV is genetically active in these astrocytes, producing high levels of the messenger molecules, the so-called mRNA, that code for the proteins required for a new virus particle. We have determined that these HIV mRNAs are specifically prevented from translating into protein. The mechanisms controlling protein translation from RNA are relatively poorly understood compared with the other control points of cellular gene expression, such as the synthesis of mRNA. This project examines how astrocytes rapidly detect the presence of HIV mRNA and alter their translation machinery to halt the expression of HIV protein. This host defence mechanism involves two key components; the cellular component that identifies and responds to the viral mRNA, and the structural features of the HIV mRNA that enable the cell to detect its viral origin. We will study how translation of HIV proteins requires both HIV and cellular factors. We will determine the impact of both viral RNA elements and viral RNA binding proteins on the translation of viral and cellular proteins. The contribution of the type-1 interferons that are produced in response to viral infection will be studied for their role in augmenting the inhibition of HIV protein translation. Since HIV infected astrocytes significantly contribute to the onset of AIDS dementia, we will sees a strategy to lock HIV into a dormant state in the brain and thereby prevent the neurodegenerative disease associated with HIV. We will use the anti-viral mechanism blocking HIV protein translation in astrocytes to protect other cell populations, such as the CD4+ lymphocytes, from HIV infection. These studies will also give insights into the general mechanisms for translational control of gene expression in human cells.Read moreRead less