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
Identifying The Physiological Conditions That Promote Lateral Gene Transfer And Evolution Of New Streptococcal Pathovars
Funder
National Health and Medical Research Council
Funding Amount
$415,907.00
Summary
In the last few decades, the diseases caused by the three human pathogens, groups A, B and G streptococcus have undergone a transformation. The exchange of DNA between these species is speculated to play a role in this changing disease association. In this proposal we will identify the specific physiological and growth conditions that promote DNA transfer. Such information may help in our understanding of how new pathogenic strains of streptococci arise.
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
Elucidation Of Proteins Expressed By Pathogenic Fungi During Animal Infection
Funder
National Health and Medical Research Council
Funding Amount
$558,267.00
Summary
Fungi cause a diverse range of diseases and are very difficult to treat. This project looks at the proteins that are made by infectious fungi while they are causing disease in animal cells. Proteins made in particularly high abundance may be essential for the fungus to live and grow in animal tissues. By specifically targeting their production, it should be possible to stop the infection without harming the host cell.
Novel Compounds For Use As Inhibitors Of Virulence Of Human Pathogens
Funder
National Health and Medical Research Council
Funding Amount
$220,500.00
Summary
There is growing concern over the emergence of multi-drug resistant strains of bacteria which are no longer treatable with the current generation of antibiotics. This highlights the urgent need for development of the next generation of therapeutic agents to supplement or replace the current antibiotics. Our research team has identified a class of compounds which are naturally produced by a marine alga that may be effective in the control of bacterial pathogens. These compounds work by interferin ....There is growing concern over the emergence of multi-drug resistant strains of bacteria which are no longer treatable with the current generation of antibiotics. This highlights the urgent need for development of the next generation of therapeutic agents to supplement or replace the current antibiotics. Our research team has identified a class of compounds which are naturally produced by a marine alga that may be effective in the control of bacterial pathogens. These compounds work by interfering with the way many pathogens regulate the production of virulence traits. Some bacteria are able to signal members of their population by the specific uptake and recognition, through a receptor protein, of chemical cues they secrete into the environment. Accumulation of these cues or signals triggers expression of the genes that code for the virulence traits. Moreover, one particular class of these signal response proteins has been identified in many pathogens and has been shown to regulate protease production and production of a protective extracellular slime layer called a capsule. If one or more of these traits can be blocked, then the virulence of the bacterium can be reduced. We have preliminary data which demonstrates that the algal compounds do in fact prevent the expression of virulence traits and thus should be useful as new agents for the treatment of disease. The causative agents of cholera and severe gatroenteritis, Vibrio cholerae and V. parahaemolyticus respectively, have one or the other of these virulence traits, but the pathogen Vibrio vulnificus has all three and therefore is an excellent model pathogen. We propose to explore the ability of the algal compounds to specifically shut down expression of virulence factors with a long term aim for the development of these compounds as novel antimicrobial therapies for the post-antibiotic era.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.
Molecular Characterization Of E. Coli That Cause Urinary Tract Infection
Funder
National Health and Medical Research Council
Funding Amount
$387,114.00
Summary
The long term goals of the proposed research are to understand the processes by which uropathogenic Escherichia coli (UPEC) cause acute, recurrent and chronic infections and to identify new UPEC targets for therapeutic intervention. Urinary tract infections (UTI) are among the most common infectious diseases of humans and a major cause of morbidity and mortality. In the USA, UTI accounts for more than 1 million hospitalizations and $1.6 billion in medical expenditures each year. It is estimated ....The long term goals of the proposed research are to understand the processes by which uropathogenic Escherichia coli (UPEC) cause acute, recurrent and chronic infections and to identify new UPEC targets for therapeutic intervention. Urinary tract infections (UTI) are among the most common infectious diseases of humans and a major cause of morbidity and mortality. In the USA, UTI accounts for more than 1 million hospitalizations and $1.6 billion in medical expenditures each year. It is estimated that one in four women and one in twenty men will develop a UTI in their lifetime. The recurrence rate is high and no treatment other than antibiotics (often inefficient) is currently available. UPEC are the primary cause of UTI. In the last grant period, we focused on the molecular interplay that exists between different surface adhesins of UPEC. We succeeded in demonstrating functional interference between adhesins, motility organelles, aggregation factors and the capsule. We also discovered and partially characterized several novel UPEC adhesins that may play a role in pathogenesis. We established two novel technology sets: a mouse model of ascending UTI and the flow chamber biofilm model. In the next grant period, we will build on these concepts and experimental systems to gain a deeper understanding of the molecular mechanisms underlying UPEC virulence. We will characterize the role of several novel UPEC surface proteins in cell adhesin, aggregation, biofilm formation and colonization of the mouse urinary tract. We will employ an integrated approach that combines a powerful bacterial genetic system, a biofilm model, a mouse UTI model, microscopy and tissue culture systems to reveal the cellular, molecular, and structural basis for the pathogenesis of UTI. The work will facilitate the development of new vaccine approaches to prevent UTI, such as novel mechanisms for strain attenuation and vaccine design. The burden of UTI disease demands such research endeavours.Read moreRead less
The Early Inflammatory Response To Virulent And Avirulent Influenza Viruses
Funder
National Health and Medical Research Council
Funding Amount
$252,761.00
Summary
Innate immune mechanisms are vital components of host defences against pathogens. In this proposal I aim to investigate the particular mechanisms that operate in early defence against influenza virus infection and compare the ability of virulent and avirulent virus strains to (i) be recognized by components of the innate immune system, and (ii) to trigger an early inflammatory response to infection. It is anticipated that virulent virus strains have adapted to avoid recognition by innate cells s ....Innate immune mechanisms are vital components of host defences against pathogens. In this proposal I aim to investigate the particular mechanisms that operate in early defence against influenza virus infection and compare the ability of virulent and avirulent virus strains to (i) be recognized by components of the innate immune system, and (ii) to trigger an early inflammatory response to infection. It is anticipated that virulent virus strains have adapted to avoid recognition by innate cells such as macrophages. By avoiding this route of uptake and destruction, the virus is free to infect and replicate in other cells of the respiratory tract. Furthermore, by evading macrophage entry, the virus avoids triggering the release of early inflammatory mediators from these cells and this may affect both the speed and the magnitude of the subsequent inflammatory response. This study will contribute to a greater understanding of factors involved in initiating and regulating inflammation in the respiratory tract following viral infection. Furthermore, the findings may provide new insights into mechanisms of virulence of influenza and other enveloped viruses.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.