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
Study Of Papillomavirus DNA Encapsidation And Formation Of Infectious Virions
Funder
National Health and Medical Research Council
Funding Amount
$214,053.00
Summary
Papillomavirus (PV) is a sexually-transmitted virus that is a major cause of cervical cancer. Our study will determine how PV is able to form new virus particles inside infected cells. This is a critical part of the virus life-cycle, and a better understanding of this process may allow it to be trageted by anti-viral treatments. In addition, we will develop a method to create non-harmful virus particles which we will use to study human immune responses to the virus.
Nuclear Import Of The HIV-1 Pre-integration Complex: Mechanism And Therapeutic Implications
Funder
National Health and Medical Research Council
Funding Amount
$425,250.00
Summary
The human immunodeficiency virus (HIV) has a unique feature distinguishing it from other retroviruses the ability to replicate in non-dividing cells such as in macrophage-microglia cells which are among the prime target cells for virus infection. The viral genome needs to be integrated into the host cell chromosome in order to infect cells productively. The host cell s genome is not normally accessible because it is located inside the nucleus, separated from the rest of the cell by the barrier o ....The human immunodeficiency virus (HIV) has a unique feature distinguishing it from other retroviruses the ability to replicate in non-dividing cells such as in macrophage-microglia cells which are among the prime target cells for virus infection. The viral genome needs to be integrated into the host cell chromosome in order to infect cells productively. The host cell s genome is not normally accessible because it is located inside the nucleus, separated from the rest of the cell by the barrier of the nuclear envelope (NE). However, HIV has found a way to transport its genome to the nucleus in a complex together with other viral-cellular proteins, the pre-integration complex (PIC), through the intact NE of non-dividing cells. This is a crucial step of viral infection and if blocked could prevent the establishment and spread of HIV infection. Thus far it is unclear how the large HIV PIC accesses the nucleus and which viral and cellular proteins are essential for the navigation of the PIC through the NE and into the nucleus. Using fluorescent labels on the key components of the HIV PIC including the DNA in combination with confocal laser scanning microscopy and a novel optical single-transporter recording technique, we will be able to visualize the PIC on its way through the NE for the first time. Mutational analyses will further identify the key residues of viral proteins and the cellular nuclear transport machinery utilized during the transport. The results of this study will literally provide a clear picture of nuclear import of the HIV PIC. The future aim of elucidating this essential step in HIV replication is to identify new targets for anti-retroviral drug interventions that may be less prone to side effects and development of resistance than the currently available drug regimens.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
HCMV Protein Kinase And DNA Polymerase Domains Involved In Antiviral Sensitivity, Viral Replication And Cell Tropism
Funder
National Health and Medical Research Council
Funding Amount
$269,250.00
Summary
Many individuals with compromised immune systems - such as those with HIV-AIDS, cancer and transplant recipients are at risk of disease from human cytomegalovirus (HCMV) infection. Currently the most effective therapies are suppression of virus replication by continuing administration of antiviral agents, principally ganciclovir (GCV), cidofovir (CDV) or foscarnet (phosphonoformic acid or PFA). The use of antivirals for increasingly longer durations in an enlarging population of patients with ir ....Many individuals with compromised immune systems - such as those with HIV-AIDS, cancer and transplant recipients are at risk of disease from human cytomegalovirus (HCMV) infection. Currently the most effective therapies are suppression of virus replication by continuing administration of antiviral agents, principally ganciclovir (GCV), cidofovir (CDV) or foscarnet (phosphonoformic acid or PFA). The use of antivirals for increasingly longer durations in an enlarging population of patients with irreversible chronic immunosuppression, has resulted in the emergence of increasing numbers of drug-resistant HCMV viruses in this group of individuals. In patients with AIDS, 7.6% of isolates in one study were shown to be GCV resistant and we have found similar levels (10.8%) in immunosuppressed Australians. Of the small number of antiviral agents with any useful activity against HCMV, GCV, and aciclovir (ACV) are nucleoside analogues. PFA is a pyrophosphate analogue that competitively inhibits pyrophosphate binding by HCMV DNA polymerase. These drugs are activated by a specific gene of HCMV (UL97 (Pk)) and a mouse virus (MCMV - M97Pk) that is very similar to HCMV. The drug then acts on a second gene encoding the DNA polymerase (HCMV UL54 DP or MCMV M54DP) to prevent viral growth. We are investigating the resistance genotypes and phenotypes in CMV resistant to 7 antiviral drugs including GCV, CDV and PFA. We have shown new resistant genotypes and are currently determining the protein-functional correlates of the genotypic changes, in order to increase understanding of the PK and DP genes, define the genetic causes of resistance, and to produce better targets for antiviral agents.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