RECOMBINANT MALARIAL PYRIMIDINE ENZYMES AS DRUG TARGETS
Funder
National Health and Medical Research Council
Funding Amount
$229,750.00
Summary
Malarial parasites have now developed resistance to most of the available drugs and there is an urgent need for drugs with new mechanisms of action. Institutions collaborating on the Malarial Genome Project have sequenced the majority of DNA in the 14 chromosomes. The nucleotide sequence available on the internet contains thousands of open reading frames (ORFs) which encode proteins essential for survival of the parasite. Many of these proteins are enzymes which are suitable targets for drug dev ....Malarial parasites have now developed resistance to most of the available drugs and there is an urgent need for drugs with new mechanisms of action. Institutions collaborating on the Malarial Genome Project have sequenced the majority of DNA in the 14 chromosomes. The nucleotide sequence available on the internet contains thousands of open reading frames (ORFs) which encode proteins essential for survival of the parasite. Many of these proteins are enzymes which are suitable targets for drug development. A knowledge of the molecular architecture of the active site of such enzymes provides a template for drug design. The malarial parasite, Plasmodium falciparum, can only synthesise pyrimidine nucleotides for DNA via the de novo pyrimidine pathway. We have cloned the genes encoding three of the enzymes of the de novo pathway using sequence information from the Malarial Genome Project. Dihydroorotase, orotate phosphoribosyltransferase, and OMP decarboxylase, catalyse reactions 3, 5 and 6 of the pathway. We have expressed these enzymes in the bacterium Escherichia coli enabling large-scale production of these drug targets. We propose to characterise the catalytic and inhibitory properties of these enzymes, and grow protein crystals for determination of atomic structures by x-ray diffraction. The structures will provide templates for rational design of new antimalarial drugs. In a second approach for develoment of new drugs, the 3 malarial enzymes will be screened against chemical libraries for inhibition of catalytic activity. The initial screen will utilise a high throughput Biacore 3000 instrument which detects strong interactions between a target enzyme and candidate inhibitors. A thorough knowledge of the catalytic mechanisms, the three-dimensional structures and novel first generation inhibitors of these 3 malarial target enzymes, will provide a strong basis for development of new antimalarial drugs.Read moreRead less
Dysregulation Of Cytokine Networks: A Key Determinant Of The Pathogenesis Of Cerebral Malaria.
Funder
National Health and Medical Research Council
Funding Amount
$480,989.00
Summary
Malaria is a parasitic disease that kills some 2 million people each year. It affects the Australian region, e.g. PNG and SE Asia. One of the most serious complications is cerebral malaria (CM). It affects the brain and is often fatal. This project will show whether the early meeting of the malaria parasite with the host's immune system determines if the infection will be a mild, resolving one or a severe, possibly lethal one causing CM. This is highly relevant to vaccine development strategies.
Evaluation Of Naturally Occurring Resistance To Direct Acting Antiviral Drugs (DAAs) In Individuals With Acute Hepatitis C Infection
Funder
National Health and Medical Research Council
Funding Amount
$333,778.00
Summary
Hepatitis C therapy in the future is likely to involve the use of Directly Acting Antivirals, which offer a better chance of treatment success and shorter treatment courses. The downside to these new agents is the possible development of drug resistance. Studies suggest that drug resistant strains may already exist in some individuals prior to treatment. This study plans to use sensitive methods to examine how common drug resistant strains are in untreated individuals with acute hepatitis C.
Molecular Mechanisms Of Ivermectin Resistance In The Ectoparasitic Mite, Sarcoptes Scabiei
Funder
National Health and Medical Research Council
Funding Amount
$289,561.00
Summary
A largely neglected parasitic disease, scabies is a significant disease of children, particularly in remote Aboriginal communities in northern Australia. The recent emergence of ivermectin resistance threatens future control of scabies. This research explores the genetic basis of ivermectin resistance in the scabies mite, developing molecular markers to identify the emergence of resistance in the community, leading to improved tools for resistance management and sustainable treatment strategies.
Modulation Of Leishmaniasis By The Proinflammatory Cytokines TNF
Funder
National Health and Medical Research Council
Funding Amount
$288,911.00
Summary
We have established a mouse model that has been genetically modified and cannot produce the cytokine tumour necrosis factor. This cytokine is secreted in the beginning of the inflammatory response. If these mice are infected with a parasite they are not able to heal the infection and die quickly. We can demonstrate that these mice cannot regulate the beginning inflammatory response and do not form a cellular infiltrate at the site of infection.
Targeting The Mannose Activation Pathway In Leishmania - Novel Drug Targets And Vaccines.
Funder
National Health and Medical Research Council
Funding Amount
$338,661.00
Summary
Leishmaniasis is a parasitic disease ranging in severity from skin lesions to fatal systemic infection. It is a serious public health problem throughout many regions of the world. Co-infection with HIV has emerged as a serious problem in Africa, South America and southern Europe. Recently, leishmaniasis has been identified in East Timor and in kangaroos in Australia. Treatment of leishmaniasis is based on chemotherapy, but currently used drugs are expensive, have high toxicity and unwanted side ....Leishmaniasis is a parasitic disease ranging in severity from skin lesions to fatal systemic infection. It is a serious public health problem throughout many regions of the world. Co-infection with HIV has emerged as a serious problem in Africa, South America and southern Europe. Recently, leishmaniasis has been identified in East Timor and in kangaroos in Australia. Treatment of leishmaniasis is based on chemotherapy, but currently used drugs are expensive, have high toxicity and unwanted side effects. They have also been compromised by the emergence of resistance in the parasite. Leishmania synthesises a range of surface molecules, which are needed for virulence and parasite survival in the host. The biosynthesis process of these molecules requires activated mannose. We have identified two novel parasite genes encoding for enzymes, which are essential for the biosynthesis of surface virulence factors. When either of these genes is deleted the parasite can no longer cause disease. This suggests that drugs targeting the two enzymes will be able to control the infection. We will produce crystals of these enzymes and solve their 3D structure using state of the art technology to screen libraries of synthetic chemicals to find candidate inhibitors of enzyme activity. When these compounds are identified we will use computer modelling to design compounds based on these inhibitors and crystal structure, which will lead to a new generation of anti-Leishmania drugs. We will also determine whether the avirulent parasites can be used as an attenuated vaccine. Recovery from infection leads to a solid immunity and protection from subsequent infection indicating that vaccination is feasible, but despite of a huge amount of research there is no antileishmanial vaccine currently available. This study will lead to potential novel antileishmanial drugs and vaccines. It will also provide fundametal new knowledge of the structure of enzymes critical for parasite virulence.Read moreRead less
Immune Dysregulation In HIV Patients With Immune Reconstitution After Highly Active Anti-retroviral Therapy
Funder
National Health and Medical Research Council
Funding Amount
$411,000.00
Summary
As HIV infection progresses to AIDS, there is a depletion of CD4 T-cells from the patient's blood and inhibition of the function of the remaining cells. Some immune defects resolve if the patient is given treatment with highly active anti-retroviral therapy (HAART), but it remains to be determined if the function of the imune system returns fully to normal. We have shown that problems with the regulation of the restored immune system in the first 6 months of treatment can lead to diseases associ ....As HIV infection progresses to AIDS, there is a depletion of CD4 T-cells from the patient's blood and inhibition of the function of the remaining cells. Some immune defects resolve if the patient is given treatment with highly active anti-retroviral therapy (HAART), but it remains to be determined if the function of the imune system returns fully to normal. We have shown that problems with the regulation of the restored immune system in the first 6 months of treatment can lead to diseases associated with Mycobacterial infections (eg: tuberculosis), CMV retinitis, hepatitis B virus or hepatitis C virus. We have defined these conditions as Immune Restoration diseases (IRD) and shown that they occur in one in four individuals who begin HAART from low baseline CD4 T-cell counts. IRD are likely to become common as therapy becomes available in Africa and Asia as patients begin treatment from low CD4 T-cell counts. There is also emerging evidence that dysregulated T-cell responses may cause disease later in the course of immune reconstitution. For example, some patients with undetectable HIV experience opportunistic infections or autoimmune disease after many months of HAART. This project will use West Australian patients receiving optimal therapy for their HIV infection. We will analyse immune activation and T-cell function in patients beginning HAART with low CD4 T-cell counts and patients who have had well-controlled HIV infection for at least 6 months. Blood samples will be collected for the measurement of immunological messengers (cytokines) known to be involved in different types of immune responses. The results will be correlated with the clinical outcome.Read moreRead less
Sensitive, Rapid And Accurate Detection Of The Emergence Of Neuraminidase Inhibitor Resistance By Real-time PCR, LCR And
Funder
National Health and Medical Research Council
Funding Amount
$118,875.00
Summary
An influenza pandemic causing by highly pathogenic H5N1 virus may occur in the near future. As a vaccine for H5N1 will not be available in the foreseeable months, antiviral drugs are the only possible choice for prophylaxis and treatment. Currently only two drugs have been clinically proven to be effective against H5N1 strain and the emergence of drug resistant in H5N1 influenza virus has been reported which may significantly hamper the treatment. Understanding and monitoring the emergence of th ....An influenza pandemic causing by highly pathogenic H5N1 virus may occur in the near future. As a vaccine for H5N1 will not be available in the foreseeable months, antiviral drugs are the only possible choice for prophylaxis and treatment. Currently only two drugs have been clinically proven to be effective against H5N1 strain and the emergence of drug resistant in H5N1 influenza virus has been reported which may significantly hamper the treatment. Understanding and monitoring the emergence of these drug resistant strains during local spreading will be critical in managing an H5N1 influenza pandemic in Australia. In the proposed project, we will develop important diagnostic tools using our world leading Rolling Circle Amplification (RCA) technology for the monitoring of the development and possible transmission of drug resistant influenza strains. Upon finishing the project, at lease three sensitive diagnostic methods will be developed for the detection of the emergence of drug resistance at the very early stage.Read moreRead less