SiRNA Induced Transcriptional Silencing Of HIV-1: Elucidating The Mechanisms And Exploring Options For Delivery
Funder
National Health and Medical Research Council
Funding Amount
$512,631.00
Summary
Current drug therapy for HIV is for life We have discovered a set of molecules that will turn off the ability of HIV to reproduce itself. These molecules are from a new family of RNA molecules . A single dose of these molecules suppress the ability of the virus to reproduce itself for more than a month. Further we have found ways of extending this supressive ability to greater than one year. These studies will tell us how these molecules work and how they might be effectively administered.
SiRNA Induced TGS Of Retroviruses: Elucidation Of Underlying Mechanisms And Their Application In Animal Models
Funder
National Health and Medical Research Council
Funding Amount
$371,502.00
Summary
AIMS To elucidate changes in DNA that accompany suppression of HIV growth caused by certain unusual RNA molecules that turn off the ability of HIV to reproduce and make the virus dormant within the infected cell. While we have discovered RNA molecules that can do this to HIV in the test tube, we wish to develop similar molecules that can be used in animal models, so that we can decide whether this technology can be developed for use in humans. We also wish to understand more clearlky the mechani ....AIMS To elucidate changes in DNA that accompany suppression of HIV growth caused by certain unusual RNA molecules that turn off the ability of HIV to reproduce and make the virus dormant within the infected cell. While we have discovered RNA molecules that can do this to HIV in the test tube, we wish to develop similar molecules that can be used in animal models, so that we can decide whether this technology can be developed for use in humans. We also wish to understand more clearlky the mechanisms underlying this effect. BACKGROUND These RNA molecules can suppress a range of pathogenic human viruses including HIV-1 in the test tube. Our novel approach appears to induce changes that are long lasting and are less susceptible to mutations by the virus that allow it to become resistant to other therapeutic strategies. RESEARCH PLAN Initially more work will be done in tissue culture to determine the optimal design of these molecules and the best way to administer them. The most promising of these designs will be tested in small groups of infected animals as a preliminary demonstration of efficacy. In parallel experiments will be performed to elucidate the mechanisms undelying the suppressive effects of these molecules. OUTCOMES AND SIGNIFICANCE This work will lead to a significant increase in our understanding of the way replication of HIV is regulated and will develop a promising new therapeutic strategy for this virus that may be applicable to other conditions.Read moreRead less
The Role Of HIV Infection Of Astrocytes In The Development Of HIV Associated Dementia
Funder
National Health and Medical Research Council
Funding Amount
$144,250.00
Summary
Dementia is an extremely common problem in the late stages of Human Immunodeficiency Virus (HIV) infection. HIV-associated dementia is the most common cause of dementia in people under 40 years of age. Despite the development of very good drugs to attack the virus, HIV-associaed dementia continues to be a major clinical problem. We are looking at the reasons why some people infected with HIV become demented and others do not. We are also looking at how best to prevent the development of dementia ....Dementia is an extremely common problem in the late stages of Human Immunodeficiency Virus (HIV) infection. HIV-associated dementia is the most common cause of dementia in people under 40 years of age. Despite the development of very good drugs to attack the virus, HIV-associaed dementia continues to be a major clinical problem. We are looking at the reasons why some people infected with HIV become demented and others do not. We are also looking at how best to prevent the development of dementia. We believe that astrocytes (an important brain cell that supports neurons) play a very important role in the development of HIV-associated dementia. With an improved understanding of the steps leading to dementia we can better plan treatments to prevent the development of this devastating complication of HIV-AIDS.Read moreRead less
Drug Resistance Mutations In The Connection Subdomain Of The HIV-1 Reverse Transcriptase
Funder
National Health and Medical Research Council
Funding Amount
$376,710.00
Summary
Human immunodeficiency virus type 1 (HIV-1) infections can be controlled with antiretroviral drugs. In the majority of patients on antiretroviral therapy the virus mutates and is no longer inhibited by the drug. The emergence of drug-resistant HIV-1 is one of the major factors that lead to loss of drug efficacy in patients. Mutations that confer drug resistance have been defined and are specific for different drug classes. Genotype assays that are used to predict drug resistance are routinely us ....Human immunodeficiency virus type 1 (HIV-1) infections can be controlled with antiretroviral drugs. In the majority of patients on antiretroviral therapy the virus mutates and is no longer inhibited by the drug. The emergence of drug-resistant HIV-1 is one of the major factors that lead to loss of drug efficacy in patients. Mutations that confer drug resistance have been defined and are specific for different drug classes. Genotype assays that are used to predict drug resistance are routinely used to guide therapeutic decisions in the treatment of HIV-1 infected individuals. For drugs that target the HIV-1 reverse transcriptase (RT), commonly used genotype kits normally analyse mutations in the first 240 out of 560 amino acids of the reverse transcriptase. This ignores the impact of mutations in other regions of the enzyme, which are potentially important in drug resistance. Recently, mutations that inhibit ribonuclease H function of the HIV-1 RT have been shown to confer high-level resistance to zidovudine, providing the precendent that mutations beyond codon 240 can confer drug resistance. Our analysis of a different region to ribonuclease H called the connection subdomain has demonstrated the presence of mutations that are highly prevalent in drug-treated versus drug naive patients. In this study we will use in vitro assays to define the effect of these mutations on drug resistance and viral fitness . We will also determine the mechanism by which these mutations confer drug resistance. Finally, using our unique database consisting of over 20,000 genotyped samples , we will establish the role of these mutations in the patient. This study is anticipated to identify clinically significant mutations that are present in the RT connection subdomain. Additionally, this study will lead to the development of more accurate genotype assays which will improve the clinical management of HIV infected individuals.Read moreRead less
SERPINB2 IS AN INDUCIBLE HOST FACTOR INVOLVED IN ENHANCING HIV-1 TRANSCRIPTION AND REPLICATION
Funder
National Health and Medical Research Council
Funding Amount
$496,446.00
Summary
SerpinB2 is one of the most abundant proteins made at sites of inflammation. We have shown that HIV-1 infection also induces SerpinB2 and that SerpinB2 then helps the virus to replicate. In this grant we seek to understand how the virus causes this protein to be made and how this protein then increases virus replication. In the human population there are different forms of SerpinB2 and this grant seeks to determine whether these different forms affect HIV-1 replications differently. It may for i ....SerpinB2 is one of the most abundant proteins made at sites of inflammation. We have shown that HIV-1 infection also induces SerpinB2 and that SerpinB2 then helps the virus to replicate. In this grant we seek to understand how the virus causes this protein to be made and how this protein then increases virus replication. In the human population there are different forms of SerpinB2 and this grant seeks to determine whether these different forms affect HIV-1 replications differently. It may for instance be possible that an individual who has a certain form of SerpinB2 may be less susceptable to AIDS following HIV-1 infection.Read moreRead less
Inhibition Of Nef-activated Src-family Kinases By CHK
Funder
National Health and Medical Research Council
Funding Amount
$514,307.00
Summary
HIV hijacks infected blood cells to produce its own proteins. Nef is one of these proteins and Nef alone is sufficient to cause an AIDS-like disease. Recently, we discovered that a protein called CHK can inhibit Nef. Our research will determine how CHK inhibits Nef and test the feasibility of drugs based on CHK. Such drugs would slow AIDS progression, assisting conventional therapies and patients' immune systems to combat the infection, leading to longer, healthier, more productive lives.
Processes Underlying Establishment And Maintenance Of The Latent HIV Resevoir And Potential Impact Of Integrase Inhibitors
Funder
National Health and Medical Research Council
Funding Amount
$318,044.00
Summary
Therapy for HIV-infected individuals is currently able to control the growth of the virus, but cannot eradicate the viral infection. This is due to a pool of CD4+ T lymphocytes which contain HIV DNA in a latent state, ready to reactivate as soon as therapy is interrupted. This project aims to better understand how this pool of latently infected CD4+ T lymphocytes is established and maintained, particularly how it is linked to the essential T cell survival signal from interleukin 7.
Controlling HIV-1 Replication In Macrophages: Cellular Regulation Of Tat Expression
Funder
National Health and Medical Research Council
Funding Amount
$466,500.00
Summary
Monocytes in the blood and macrophages in the tissues are the scavenger cells of the body's immune system. They are among the first cells to become infected with HIV and harbour the virus for the lifetime of the cell, which can be up to several years. While monocytes are only infected at low frequency, macrophages in tissues can be infected in high numbers and can contribute significantly to virus production. Current potent combination therapies are unable to clear the virus from these cells and ....Monocytes in the blood and macrophages in the tissues are the scavenger cells of the body's immune system. They are among the first cells to become infected with HIV and harbour the virus for the lifetime of the cell, which can be up to several years. While monocytes are only infected at low frequency, macrophages in tissues can be infected in high numbers and can contribute significantly to virus production. Current potent combination therapies are unable to clear the virus from these cells and have limited efficacy in this cell type. There are no treatments which specifically target HIV infection in these important viral reservoirs. We have found that in a laboratory model of HIV infection in macrophages, the infection changes from active and productive to chronic and non-productive over the course of several weeks. This change is characterised by a decrease in one of the virus' important regulatory proteins, Tat. In this project, we aim to determine how the cells induce this change in the virus' growth. This may lead to novel ways in which HIV could be controlled in these important cells by targeting cellular rather than viral proteins. Controlling infection in macrophages and preventing spread of the virus to other cells would assist with the problem of the virus rebounding rapidly when patients stop or interrupt therapy and would help with long term treatment and management, leading to eventual eradication of the virus from the body.Read moreRead less
HIV currently infects ~40 million people world-wide, causing ~3 million deaths in 2003, mainly in the world's poorest countries. A cheap, effective vaccine seems the best means of preventing the spread of the epidemic. The two main approaches to vaccination are either to make antibodies (which bind to and inactivate the virus), or killer T cells (which kill infected cells). Many of these vaccines are now being tested in monkeys. The results of killer T cell vaccination trials have been both enco ....HIV currently infects ~40 million people world-wide, causing ~3 million deaths in 2003, mainly in the world's poorest countries. A cheap, effective vaccine seems the best means of preventing the spread of the epidemic. The two main approaches to vaccination are either to make antibodies (which bind to and inactivate the virus), or killer T cells (which kill infected cells). Many of these vaccines are now being tested in monkeys. The results of killer T cell vaccination trials have been both encouraging and disappointing. The vaccines do not appear able to prevent the monkeys from getting infected with the virus. However, in many cases even though the monkeys become infected with HIV, they do not get the usual disease associated with AIDS, and hence live with rather than die from this infection. The aims of this project are to use statistical analysis, and more complex mathematical and computer models to try to analyse the data generated by these vaccine trials and to understand how these partially effective vaccines help control virus. For example, even if a vaccine does not prevent infection, we can investigate whether it slowed viral growth, or increased killing of infected cells, and if so, whether an increase in this response could be effective. In preliminary work we have analysed data from a vaccination trial performed in Boston. The results of this study suggest that the reason vaccinated monkeys still become infected is that the killer T cells produced by the vaccine do not appear to activate for the first 10 days of infection. In these first 10 days the virus grows normally and is able to establish a foothold for continuing infection. By contrast, we find that antibodies act extremely early after infection. The methods we propose have not been used before to study vaccines, and by studying the kinetics of the virus and immune response from a large number of vaccine trials we hope to help identify the optimal vaccine design.Read moreRead less
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.