Contribution Of Shigella And Escherichia Coli Pathogenicity Islands To Diarrhoeal Disease
Funder
National Health and Medical Research Council
Funding Amount
$303,677.00
Summary
Diarrhoea resulting from infection with Shigella and Escherichia coli is a major cause of sickness and death in the developing world, especially in children. Even in Australia, these bacteria, which may be food borne, are occasionally responsible for life threatening infections. In this study, we will investigate the contribution to diarrhoeal disease of large fragments of foreign DNA which have been recently acquired by these bacteria. We will characterise several of these elements in detail, i ....Diarrhoea resulting from infection with Shigella and Escherichia coli is a major cause of sickness and death in the developing world, especially in children. Even in Australia, these bacteria, which may be food borne, are occasionally responsible for life threatening infections. In this study, we will investigate the contribution to diarrhoeal disease of large fragments of foreign DNA which have been recently acquired by these bacteria. We will characterise several of these elements in detail, identifying novel virulence determinants and toxins in the process. We will also explore the means by which these packages of nasty DNA transfer between bacteria and investigate their potential to give rise to new, more virulent strains of bacteria. This study is particularly significant because it will lead to an improved understanding of how bacteria cause disease and may help to guide us in developing better strategies for the prevention of bacterial diarrhoea. Specifically, the work done on characterising large clusters of virulence genes will allow us to construct safer bacterial vaccines and we expect that in the future this knowledge will contribute to the development of new and better diagnostic and therapeutic agents against these harmful bacteria.Read moreRead less
Development Of Improved Preventative Therapeutic Strategies For The Control Of Infectious Disease
Funder
National Health and Medical Research Council
Funding Amount
$4,000,000.00
Summary
A major objective of this Australia Fellowship application is to provide a mechanism whereby, for the first time in my career, I can devote myself full-time to my program of research. This program addresses an issue of global significance, namely the control of bacterial infectious diseases. These continue to cause massive global morbidity and mortality and constitute a profound threat to human health, in spite of the availability of antimicrobial drugs for over 60 years. WHO estimates that bact ....A major objective of this Australia Fellowship application is to provide a mechanism whereby, for the first time in my career, I can devote myself full-time to my program of research. This program addresses an issue of global significance, namely the control of bacterial infectious diseases. These continue to cause massive global morbidity and mortality and constitute a profound threat to human health, in spite of the availability of antimicrobial drugs for over 60 years. WHO estimates that bacterial infections are responsible for >10 million deaths p.a., and the economic impact is inestimable. For most major pathogens, vaccines are either unavailable or have serious shortcomings. Resistance to commonly used antimicrobials is increasing at an alarming rate, and modern travel has assisted the rapid global dissemination of highly resistant and virulent clones. Morbidity and mortality are also predicted to increase as a consequence of human-induced environmental changes and the growing proportion of the population with increased susceptibility to infection. Effective management of bacterial infectious diseases in the 21st century will require a two-pronged approach involving the development of cheaper and more effective vaccines, as well as novel anti-infectives refractory to known resistance mechanisms. However, formulation of optimal therapeutic and preventative strategies demands a thorough understanding of the biology of disease, particularly the complex interactions between bacterial pathogens and their human hosts. I have also played a leadership role in establishing the Pneumococcal Vaccine Consortium, which has just submitted a co-ordinated suite of multicentre proposals to PATH Vaccine Solutions to fund final preclinical testing, GMP scale-up and Phase I-II-III trials of protein-based pneumococcal vaccines that we have developed. The PATH accelerated pneumococcal vaccine development program is of enormous potential significance, because there is now a very real probability of pneumococcal protein vaccines being fast-tracked into human trials. Our aim is to create a direct pipeline from antigen discovery in the collaborators’ laboratories into the clinic. If successful, these vaccines could save millions of lives. This will be of enormous satisfaction to me personally, as it was I who originally proposed and demonstrated “proof of principle” for the vaccine potential of pneumococcal proteins, and I have been advocating assessment of their protective efficacy in humans for over 20 years. Thus, receipt of an Australia Fellowship will undoubtedly further support the internationalisation of Australian medical research.Read moreRead less
Characterising The Role Of Streptokinase Polymorphism In Invasive Pathogenesis Of Streptococcus Pyogenes.
Funder
National Health and Medical Research Council
Funding Amount
$480,535.00
Summary
Invasive bacterial pathogens such as Streptococcus pyogenes, can hijack host proteins and use them to facilitate the disease process. S. pyogenes secrete streptokinase to activate a host protease (plasminogen) which is used by the bacterium to invade through host tissue. This project will characterise the molecular mechanisms involved in streptokinase mediated activation of plasminogen which will assist the generation of novel therapeutics to treat invasive diseases.
Coordinate Expression Of Virulence Factors In Pathogenic Escherichia Coli
Funder
National Health and Medical Research Council
Funding Amount
$239,250.00
Summary
Escherichia coli is a versatile pathogen capable of causing a range of disease types including diarrhoea, dysentery, haemolytic uremic syndrome, bladder and kidney infections, septicaemia, pneumoniae and meningitis. Infections due to pathogenic E. coli may be limited to mucosal surfaces or can disseminate throughout the body. Amongst the different classes of pathogenic E. coli, diarrheagenic strains (namely enterotoxigenic and enteroinvasive E. coli) are responsible for the death of an estimated ....Escherichia coli is a versatile pathogen capable of causing a range of disease types including diarrhoea, dysentery, haemolytic uremic syndrome, bladder and kidney infections, septicaemia, pneumoniae and meningitis. Infections due to pathogenic E. coli may be limited to mucosal surfaces or can disseminate throughout the body. Amongst the different classes of pathogenic E. coli, diarrheagenic strains (namely enterotoxigenic and enteroinvasive E. coli) are responsible for the death of an estimated one million humans per year, mainly in third world countries. The majority (80%) of urinary tract infections (UTIs) in humans are caused by E. coli and in Australia alone there are about 250,000 cases per year. It is estimated that one in four women and one in twenty men will develop a urinary tract infection in their lifetime. Pathogenic E. coli strains are normally equipped with multiple virulence factors and there is mounting evidence that the expression of such factors is finely orchestrated by mutual regulatory cross-talk. For example, expression of flagella (which provide motility) and adhesins (which provide attachment) are fundamentally counteracting phenotypes, yet the molecular and genetic mechanisms that coordinate their expression are unknown. I plan to examine inter-system cross-regulation of bacterial surface structures (namely adhesins, autoaggregaters, capsules and flagella). The aim is to understand on the molecular level how microorganisms orchestrate expression of virulence factors and will have consequences for our understanding of microbial pathogenicity. The strategy outlined may lead to new routes for strain attenuation and perhaps a method for vaccine strain construction. The research will be performed in collaboration with international high profile partners.Read moreRead less
Analysis And Regulation Of Leptospiral Virulence Factors.
Funder
National Health and Medical Research Council
Funding Amount
$630,465.00
Summary
Leptospirosis is a globally important infectious disease caused by Leptospira spp. This project aims to identify and characterise factors which play a role in disease development by knocking out genes, then investigating the impact on overall gene-protein expression in the mutant strain and its ability to cause disease. This will allow us to gain insights on mechanisms by which Leptospira spp. cause disease, leading to development of better methods of disease control and prevention.
Origins And Relationships Of Shigella And Enteroinvasive Escherichia Coli
Funder
National Health and Medical Research Council
Funding Amount
$377,310.00
Summary
Shigella is a well known highly infectious human pathogen with as few as 10 cells allowing effective spread by infected food or water, and also by person to person contact. Shigellosis is a particularly significant disease for children due to lack of pre-existing immunity and greater chance of transfer by fecal-oral route. One group of E. coli called Enteroinvasive E. coli (EIEC) resembles Shigella in many aspects from disease symptoms to biochemical properties. EIEC is a major cause of diarrhoe ....Shigella is a well known highly infectious human pathogen with as few as 10 cells allowing effective spread by infected food or water, and also by person to person contact. Shigellosis is a particularly significant disease for children due to lack of pre-existing immunity and greater chance of transfer by fecal-oral route. One group of E. coli called Enteroinvasive E. coli (EIEC) resembles Shigella in many aspects from disease symptoms to biochemical properties. EIEC is a major cause of diarrhoea in less developed countries and has also caused large outbreaks in developed countries. It is now clear that Shigella and E. coli are really one species. EIEC and Shigella strains are variants of E. coli with humans as the only host. However separation of the two in all records and most studies means that there is no integrated understanding of the forms. We aim to study the relationships of Shigella and EIEC and expect significant insights into the origins of Shigella-EIEC. This will facilitate diagnosis and understanding of the disease(s) and lead to a far better classification . EIEC-Shigella strains have arisen from other E. coli independently. This has happened seven times in the derivation of Shigella and we expect more such events with EIEC. An interesting phenomenon during this process is that strains tend to lose metabolic functions. In this study we will look at what, why and how functions are lost. O antigens are important in evading the host immune system. Shigella strains obtained many O antigens, the majority apparently from other species. This is quite likely the key to its success. We will look at how Shigella obtained new O antigens. This project will be significant in the understanding of Shigell-EIEC, a very significant human pathogen, and in general for understanding emergence of new pathogens.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
Mechanism Of Exacerbations In Cystic Fibrosis Lung Disease
Funder
National Health and Medical Research Council
Funding Amount
$254,876.00
Summary
Cystic Fibrosis lung disease is characterised by infeciton with a bug called Pseudomonas aeruginosa. Patients ultimately die in their mid-30's as a result of this infection, but lung decline is accelerated by episodes of exacerbation when patients cough up large volumes of mucky sputum. We are studying the casue of exacerbations by looking at bacterial behaviour and the response of the immune system. We will use this information to try and develop early warning signals and better treatments.
Protease-activated Receptor-1 (PAR-1) And Regulation Of Helicobacter Pylori Induced Mucosal Inflammation
Funder
National Health and Medical Research Council
Funding Amount
$478,090.00
Summary
Helicobacter pylori infections cause chronic gastritis which in some people results in stomach cancer or ulcers. We have identified a novel host factor, PAR-1, important for preventing this inflammation. We will use mice to identify how this molecule protects against gastritis and samples from patients to examine its importance in human disease. This will help explain why these diseases develop in some people but not others and perhaps allow identification of those at risk of developing disease.