Transposable Element Mobility And Chromosomal Rearrangement In The Fungal Pathogen Cryptococcus During Human Infection
Funder
National Health and Medical Research Council
Funding Amount
$322,028.00
Summary
Pathogenic fungi present in the environment have emerged as an increasingly common threat to human health. Cryptococcus neoformans and the closely related species Cryptococcus gattii are the leading causes of life-threatening fungal meningitis, and Australia is one of the few countries where both species are prevalent. Although C. neoformans is an increasingly common cause of infection in immunocompromised patients such as those suffering from AIDS, approximately one in four infected individuals ....Pathogenic fungi present in the environment have emerged as an increasingly common threat to human health. Cryptococcus neoformans and the closely related species Cryptococcus gattii are the leading causes of life-threatening fungal meningitis, and Australia is one of the few countries where both species are prevalent. Although C. neoformans is an increasingly common cause of infection in immunocompromised patients such as those suffering from AIDS, approximately one in four infected individuals has no apparent immune system defect. For patients with AIDS, in the absence of antiretroviral therapy cryptococcal infection is incurable and requires lifelong treatment with antifungal medication to keep the infection in check. During infection, Cryptococcus is under tremendous stress enforced not only by the immune system and the presence of antifungals, but also by the high temperature, nutrient limiting environment encountered in the host. The proposed research will reveal how Cryptococcus evolves in this environment to enable persistence of infection despite medical intervention. I propose that naturally occurring mobile genetic elements present in the Cryptococcus genome cause chromosomal rearrangements during long term infection to produce gene deletions and duplications that facilitate survival. By characterising these changes and the genes associated with them, the research will identify novel genes involved in pathogenesis and will increase our understanding of the infection process. The expected outcome of this project is a detailed understanding of the roles mobile element movement and chromosomal rearrangement play in Cryptococcus during infection, and how these affect genes that contribute to the pathogenic process. The fundamental knowledge gained from this study will facilitate studies designed to combat infections in the clinical setting, provide new drug targets and help foster the development of more effective therapies.Read moreRead less
Molecular Mechanisms Of Persistence Of Mycobacterium Tuberculosis
Funder
National Health and Medical Research Council
Funding Amount
$398,142.00
Summary
Mycobacterium tuberculosis is the bacterium that causes tuberculosis (TB. It infects about third of all people in the world and kills several million people each year. People with active TB spread the mycobacteria in aerosols from their breath. When another person inhales an infected aerosol the mycobacteria enter their lungs and establish a new infection. During the course of infection M. tuberculosis is exposed to a variety of harsh environments inside the lungs which normally kill other bacte ....Mycobacterium tuberculosis is the bacterium that causes tuberculosis (TB. It infects about third of all people in the world and kills several million people each year. People with active TB spread the mycobacteria in aerosols from their breath. When another person inhales an infected aerosol the mycobacteria enter their lungs and establish a new infection. During the course of infection M. tuberculosis is exposed to a variety of harsh environments inside the lungs which normally kill other bacteria. M. tuberculosis is able to survive and adapt to those harsh environments. M. tuberculosis has an especially thick and tough cell wall which protects it. M. tuberculosis can adapt to the environments it encounters in a patient by changing their cell walls. The wall also protects mycobacteria from chemicals so it is resistant to many common antibiotics. There are some drugs to treat TB however M. tuberculosis is building up resistance to those drugs so we need to find new ones We will determine how mycobacteria synthesize their special cell wall and how they adapt during an infection. If we know how the details of how M. tuberculosis protects itself then we can find potential weakness which could be targets for the development of new drugs to treat TB.Read moreRead less
Dissemination And Virulence Properties Of The She Pathogenicity Island Of Shigella Flexneri.
Funder
National Health and Medical Research Council
Funding Amount
$110,625.00
Summary
Bacterial species belonging to the genus Shigella are responsible for intestinal diseases ranging from mild diarrhoea to life threatening bacillary dysentery. Such diseases kill over a million people, mainly infants in developing countries, every year and lead to serious morbidity and mortality even in industrialised countries with well developed health care systems. In many cases the virulence of Shigella species is augmented by large fragments of DNA, called pathogenicity islands, that carry g ....Bacterial species belonging to the genus Shigella are responsible for intestinal diseases ranging from mild diarrhoea to life threatening bacillary dysentery. Such diseases kill over a million people, mainly infants in developing countries, every year and lead to serious morbidity and mortality even in industrialised countries with well developed health care systems. In many cases the virulence of Shigella species is augmented by large fragments of DNA, called pathogenicity islands, that carry genes which contribute to the development of disease (pathogenesis) in humans. Pathogenicity islands are important genetic elements which appear to spread independantly throughout bacterial populations and therefore contribute to the emergence of new virulence traits in bacteria. Recently, we identified two related pathogenicity islands carried by both Shigella flexneri and other species of the genus Shigella. The two pathogenicity islands belong to a unique class of genetic elements found in Shigella species and virulent strains of the intestinal bacterium E. coli. Our current study is aimed at (1) understanding the mechanisms by which one of these islands, the she pathogenicity island, spreads from one bacterial strain to another to introduce disease-producing or virulence genes to new bacteria and (2) to study how the sigA virulence gene, carried on the she pathogenicity island, contributes to disease development in humans. We know that sigA encodes a protein toxin which contributes to the loss of fluid from the intestines of rabbits that have been experimentally infected with Shigella flexneri. We propose to study the structure and function of the SigA protein to determine how it interacts with tissues to produce a pathological state. Such studies will enhance our understanding of the process of disease development and contribute to the investigation and assessment of new strategies for therapeutic intervention.Read moreRead less
GPI Anchored Forms Of The Dengue Virus NS1 Protein: Production And Role In Pathogenesis
Funder
National Health and Medical Research Council
Funding Amount
$203,448.00
Summary
Dengue viruses are carried by mosquitoes and infect millions of people around the world, particularly in tropical countries of SE Asia, Central and South America, Africa and recently in Australia (North Queensland and NT). There is no vaccine or drug available for preventing or treating the infections, which are characterised by severe illness that involves inflammation and fevers that can sometimes be fatal. This study focuses on an unusual form of a dengue virus protein (called NS1) which we h ....Dengue viruses are carried by mosquitoes and infect millions of people around the world, particularly in tropical countries of SE Asia, Central and South America, Africa and recently in Australia (North Queensland and NT). There is no vaccine or drug available for preventing or treating the infections, which are characterised by severe illness that involves inflammation and fevers that can sometimes be fatal. This study focuses on an unusual form of a dengue virus protein (called NS1) which we have identified. We plan to study the role that this protein plays in the more severe and often fatal forms of dengue infection (dengue haemorrhagic fever and dengue shock syndrome). In these more severe and life threatening forms of dengue the blood vessels of these patients become leaky. It is thought that this is caused by the secretion of certain chemicals (cytokines) from infected cells. We have shown that dengue infected human cells, which have the unusual form of NS1 protein on their surface, are capable of being activated by antibodies. Antibodies are proteins which are produced by the human body to fight infection. We aim to study whether cytokines are secreted from infected human blood cells activated in this way and whether these cytokines cause blood vessels to become leaky. We will also study how the virus produces this variant form of NS1 in the two host species that the virus infects; mosquito and human. These studies will increase our understanding of dengue virus infection and will provide valuable information concerning the role that this unusual form of the degue virus protein NS1 plays in the severe forms of dengue fever; dengue haemorrhagic fever and dengue shock syndrome.Read moreRead less
Regulatory Networks Controlling The Interaction Of Neisseria Gonorrhoeae With The Human Host
Funder
National Health and Medical Research Council
Funding Amount
$361,091.00
Summary
What does Neisseria gonorrhoeae switch on when entering a human cell? Neisseria gonorrhoeae is the causative agent of the sexually transmitted disease (STD) gonorrhoea and globally causes approximately 20-60 million new cases per annum (WHO). Gonococcal infection is the leading cause of pelvic inflammatory disease in women and ~ one third of patients will become infertile. Increased levels of resistance to traditional antibiotics have raised concerns for future treatment options. To date no succ ....What does Neisseria gonorrhoeae switch on when entering a human cell? Neisseria gonorrhoeae is the causative agent of the sexually transmitted disease (STD) gonorrhoea and globally causes approximately 20-60 million new cases per annum (WHO). Gonococcal infection is the leading cause of pelvic inflammatory disease in women and ~ one third of patients will become infertile. Increased levels of resistance to traditional antibiotics have raised concerns for future treatment options. To date no successful vaccine strategies have been developed for this organism, primarily because the cell surface proteins elicit limited immunological protection against other strains. To enable the development of innovative approaches to the control of gonococcal infections, we propose to investigate the regulatory networks in gonococci that are important for initial colonization and survival in the human host. We will examine the role of a class of proteins, called sigma factors, that control the expression of a large number of genes in a concerted fashion. The sigma factors themselves do not recognize environmental signals, but their activity is controlled by a complicated array of proteins that are responsive to changing conditions in the bacterial cell. We have for the first time in any bacterial pathogen, identified all of the genes controlled by sigma factors in the obligate human pathogen, Neisseria gonorrhoeae. We have also found that the mechanisms controlling the activity of the sigma factors in this organism are different to those found in other bacterial pathogens. Our aim is to understand the mechanisms that control sigma factors and to gain insight into how N. gonorrhoeae sense and responds to the host cell during infections.Read moreRead less
A Study Of Muscarinic Receptors In Brain Tissue Obtained Postmortem From Subjects With Schizophrenia
Funder
National Health and Medical Research Council
Funding Amount
$354,810.00
Summary
The research outlined in this proposal will examine the molecular make up of certain regions of the human brain and determine if components within those regions are altered in tissue from subjects with schizophrenia. Schizophrenia is a serious psychiatric illness that affects approximately 1% of the Australian population and the research described in this proposal seeks to help understand the cause of the illness and-or to assist in the development of new drugs with which to treat the illness. T ....The research outlined in this proposal will examine the molecular make up of certain regions of the human brain and determine if components within those regions are altered in tissue from subjects with schizophrenia. Schizophrenia is a serious psychiatric illness that affects approximately 1% of the Australian population and the research described in this proposal seeks to help understand the cause of the illness and-or to assist in the development of new drugs with which to treat the illness. The goal of the research outlined in this proposal is to determine if there are changes in specific molecules in the brain, termed muscarinic receptors. The muscarinic receptors are one way that a chemical in the brain called acetylcholine can communicate with the nerve cells in the brain. Acetylcholine is known to control important functions of the brain such as in memory, cognition and learning, all of these functions are thought to be affected in schizophrenia. Importantly, the control of all these functions involve muscarinic receptors and therefore, changes in those receptors could well produce some of the symptoms of schizophrenia. We now wish to extend our early studies which suggest there may be changes in muscarinic receptors in the brain of subjects with schizophrenia to determine which of the 5 muscarinic receptors are affected in which region of the brain by the pathology of the illness. From our existing data, we would predict that these studies will add weight to the argument that muscarinic receptors are altered in schizophrenia and provide vital information as to how drugs that target these receptors may be used to treat the illness.Read moreRead less