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
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
HIV infection is a dynamic process, in which the host immune response tries to control viral growth and keep up with the rapid evolution of the virus. This project assembles an interdisciplinary team of mathematicians and biologists to use a modelling approach to understand the dynamics of viral infection, viral evolution, and immune control in the infected individual. The insights gained from this project will help in the development of new drug and vaccination strategies.
Silent Mutations In The HIV-1 Reverse Transcriptase Selected During Antiretroviral Therapy
Funder
National Health and Medical Research Council
Funding Amount
$555,325.00
Summary
This project seeks to determine the role of silent mutations in the HIV reverse transcriptase that are selected during drug therapy in HIV infected individuals on HIV fitness, reverse transcriptase function and the emergence of drug resistance. This study will increase our understanding of the mechanisms by which the virus evades the effects of antiretrovirals and will provide a rationale for deciding on the best drug combinations for use in patients infected with specific HIV strains (clades).
Viral Determinants Of HIV-1 Transcriptional Latency In The Central Nervous System: Impact On Cure Strategies
Funder
National Health and Medical Research Council
Funding Amount
$847,521.00
Summary
This grant will identify the factors responsible for HIV-1 latency in the CNS, and will determine the effect of drugs aimed at reversing latency both on HIV-1 within the CNS, and also on the cells of the CNS.
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
Current combination antiviral therapy can't cure an HIV infection because long-lived T-cells carrying latent HIV DNA can rekindle the infection when drugs are removed. We will study elements in HIV genetic code that control expression of HIV proteins from latent HIV. A detailed molecular understanding of the structure and function of these HIV RNA elements and the viral and host cell factors that interact with them will expose new targets for therapy of latent HIV.
Molecular Studies Of The Astrocyte Reservoir Of HIV-1 In The Central Nervous System
Funder
National Health and Medical Research Council
Funding Amount
$592,661.00
Summary
HIV infects the brain causing dementia in 10-20% patients. Strategies aimed at eradicating HIV infection fail to take into account CNS infection. Understanding the way in which HIV enters, infects and replicates in the brain is pivotal in development of drugs to prevent brain infection and dementia. Our studies have shown that HIV infection of the brain involves mechanisms distinct to those observed for blood and other organs. This study seeks to clarify such mechanisms.
Molecular Studies Of The Astrocyte Reservoir Of HIV-1 In The Central Nervous System
Funder
National Health and Medical Research Council
Funding Amount
$533,828.00
Summary
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. HIV infects the central nervous system and causes HIV associated dementia in 10-20% of patients with AIDS. Despite the introduction of highly active antiretroviral therapy the prevalence in Australia continues to rise and studies have shown that the incidence has been under represented in the South east Asian region. Infection of the ....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. HIV infects the central nervous system and causes HIV associated dementia in 10-20% of patients with AIDS. Despite the introduction of highly active antiretroviral therapy the prevalence in Australia continues to rise and studies have shown that the incidence has been under represented in the South east Asian region. Infection of the CNS has two major implications for the treatment of AIDS patients. Firstly, HIV-associated dementia is the most common cause of dementia in people under 40 and this continuing increase in the number of young adults with dementia is placing increased pressure on health resources in the community. Secondly, strategies aimed at eradicating HIV infection from AIDS patients have thus far have failed to take into account the important and unique viral reservoir present in the CNS of an infected patient. The mechanisms involved in HIV-1infection of the brain remain unclear. Understanding the mechanisms by which HIV enters, infects and replicates the brain, are pivotal to the development of regimes to prevent infection of the brain in the first instance as well as development of targeted drug therapy to prevent dementia. Our preliminary studies have shown that HIV infection of the brain involves unique HIV virus and cellular mechanism distinct to those observed for the blood and other organs. This study seeks to clarify such mechanisms. This study will contribute to a greater understanding of how HIV-1 enters the brain and causes dementia, both of which are essential to the development of new drugs to treat HIV-1 infection.Read moreRead less