Role Of Regulatory Genes In The Gastrointestinal Pathogen, Clostridium Difficile
Funder
National Health and Medical Research Council
Funding Amount
$287,036.00
Summary
When patients are treated in hospital with antibiotics they sometimes develop chronic diarrhoea or colitis syndromes that are very difficult and expensive to treat. This project involves the analysis of the bacterium that generally causes these gastrointestinal diseases. We know that this microorganism is present in the hospital environment and that it produces potent protein toxins that are responsible for these diseases but we know little about the actual disease process. In most bacteria that ....When patients are treated in hospital with antibiotics they sometimes develop chronic diarrhoea or colitis syndromes that are very difficult and expensive to treat. This project involves the analysis of the bacterium that generally causes these gastrointestinal diseases. We know that this microorganism is present in the hospital environment and that it produces potent protein toxins that are responsible for these diseases but we know little about the actual disease process. In most bacteria that cause disease there are regulatory networks that control the expression of the genes responsible for the disease process. In this project, we aim to develop an understanding of how these regulatory networks operate in this particular bacterium. The latest techniques of molecular biology will be used to investigate several specific regulatory genes at the functional level. Since the entire DNA sequence of this bacterium is now known we will also use a broader research approach that makes use of this knowledge to examine all of potential regulatory networks that exist in this bacterium. Finally, we will develop new methods for the genetic analysis of the causative bacterium so that we will be better able to elucidate the role of specific genes in the disease process. By understanding how this bacterium controls the production of the proteins that interact with human intestinal cells to cause disease we hope to be able to prevent such diseases from occurring. The successful completion of the project therefore will make a major contribution to the development of improved methods for the control and treatment of these chromic diarrhoea and colitis syndromes.Read moreRead less
Shigella Flexneri O Antigen Polysaccharides: Biosynthesis, Function In Virulence, And Interaction With IcsA/VirG
Funder
National Health and Medical Research Council
Funding Amount
$468,055.00
Summary
Shigella flexneri bacteria cause dysentery in millions of humans each year. The bacterium invades and replicates within the cells of the large intestine. Inside cells, S. flexneri is able to use the host cell's actin-based motility machinery to become motile within the cells, and this can be seen as F-actin comet tails extending from one end of the cell. Bacterial cell surface components residing in the outer membrane are important for the bacterium's ability to cause disease. Two of these compo ....Shigella flexneri bacteria cause dysentery in millions of humans each year. The bacterium invades and replicates within the cells of the large intestine. Inside cells, S. flexneri is able to use the host cell's actin-based motility machinery to become motile within the cells, and this can be seen as F-actin comet tails extending from one end of the cell. Bacterial cell surface components residing in the outer membrane are important for the bacterium's ability to cause disease. Two of these components (lipopolysaccharides (LPS) and their polysaccharide chains (O antigens), and IcsA-VirG protein)) are required for initiating actin polymerisation, and mutations affecting synthesis of these components reduce ability to cause disease. In previous studies we have found that O antigen and the synthesis and function of IcsA are interrelated. This project will study how the O antigens are synthesised and their chain length determined by the Wzz protein, and the Wzz structure in relation to its function will also be characterised. The role played by O antigen in intracellular motility will be studied to determine the mechanisms involved. Infection of cells and cell free extracts, antibodies, and an enzyme which specifically degrades the O antigen, will be used to study how O antigen affect the interaction between bacteria with human cell proteins. The relationship between O antigen and IcsA function will be studied using monoclonal antibodies raised to IcsA. The effect of LPS on the outer membrane protease IcsP will be investigated, as will the effect of LPS lipid A mutations on O antigen and virulence. These studies will contribute to a better understanding of the biosynthesis of an ubiquitous bacterial cell surface component (O antigen), its function as a virulence factor in bacterial interactions with host cells. This may lead to novel therapeutic strategies to prevent and control Shigellosis and other bacterial infections.Read moreRead less
Virulence Strategies Of LEE-negative Shiga Toxigenic Escherichia Coli
Funder
National Health and Medical Research Council
Funding Amount
$230,246.00
Summary
Shiga toxigenic Escherichia coli (STEC) are a diverse group of pathogens that cause serious gastrointestinal disease in humans, which can lead to life-threatening complications. This project is aimed at understanding how these bacteria cause disease, and is focused on a subset of STEC strains that are highly virulent and produce a novel cytotoxin. A better understanding of the pathogenic mechanisms of STEC is essential for development of improved therapeutic and preventative strategies.