Regulatory Networks Controlling Virulence In Neisseria Gonorrhoeae And Neisseria Meningitidis.
Funder
National Health and Medical Research Council
Funding Amount
$147,500.00
Summary
Bacteria that cause disease produce substances called virulence determinants, often on their cell surface. These virulence determinants are either directly involved in allowing infection to take place, or cause the damage that we recognize as an infectious disease. Some virulence determinants are produced all the time, while others are only made under particular conditions, that is, their expression is regulated. To target efforts in the development of new vaccines and treatments, it is importan ....Bacteria that cause disease produce substances called virulence determinants, often on their cell surface. These virulence determinants are either directly involved in allowing infection to take place, or cause the damage that we recognize as an infectious disease. Some virulence determinants are produced all the time, while others are only made under particular conditions, that is, their expression is regulated. To target efforts in the development of new vaccines and treatments, it is important to identify all the virulence determinants produced by a particular bacterial species, but also to know which are regulated, and the environmental signals that determine their expression. Neisseria gonorrhoeae and Neisseria meningitidis are two important disease-causing bacteria that exclusively infect humans and cause gonorrhoea, and meningitis. The complete DNA sequence of both of these bacteria is now known. From computer analysis of these data, it appears that these bacteria have few of the specific regulatory systems that are present in other bacteria. Because of the limited repertoire of regulatory systems still present in N. gonorrhoeae and N. meningitidis, it is feasible to mutate each one and determine which are involved in regulation of virulence determinants. We have made copies of every individual gene found in the DNA sequence of these bacteria and have attached each one individually to a glass slide to form a microarray measuring 18mm x 18mm. This microarray will allow us to monitor the expression of every gene in these bacteria in response to environmental signals. This information will be used to identify all the virulence genes controlled by each regulatory system. Such an analysis has never been previously achieved for any bacterial species, because of the number and complexity of the regulatory systems usually present.Read moreRead less
Identification And Characterisation Of Novel Virulence Genes In Attaching And Effacing Strains Of Escherichia Coli
Funder
National Health and Medical Research Council
Funding Amount
$281,320.00
Summary
Some varieties of Escherichia (E.) coli are harmless bacteria that live in the healthy intestinal tract, whereas others can cause diarrhoea. Those varieties of E. coli which cause diarrhoea include so-called enteropathogenic E. coli (EPEC), which is a leading cause of life- diarrhoea in infants and young children in less developed countries, and enterohaemorrhagic E. coli (EHEC) the cause of hamburger disease. These bacteria are able to cause disease because they possess specific genetic informa ....Some varieties of Escherichia (E.) coli are harmless bacteria that live in the healthy intestinal tract, whereas others can cause diarrhoea. Those varieties of E. coli which cause diarrhoea include so-called enteropathogenic E. coli (EPEC), which is a leading cause of life- diarrhoea in infants and young children in less developed countries, and enterohaemorrhagic E. coli (EHEC) the cause of hamburger disease. These bacteria are able to cause disease because they possess specific genetic information that is absent from harmless varieties of E. coli. Although many of these disease-associated genes have been identified, the specific role of many of them is not known. In addition, it seems likely that many more genes of this type remain to be discovered. The fact that EPEC is host specific means that the mechanisms by which these bacteria cause disease can only be investigated in humans. This is extremely limiting for the number and type of investigations that can be performed. However, there are rabbit-specific strains of EPEC which cause a disease in rabbits that is indistinguishable from that caused by EPEC in children. The aims of this study are to use the rabbit model of diarrhoea to learn more about the contribution of certain specific factors of EPEC to disease causation and to discover new factors of this type. This will be achieved by three complementary strategies: (1) investigating rabbit E. coli for virulence genes and determining if they are present in human strains; (2) examining the effect of inactivating these genes on the ability of E. coli to cause diarrhoea in rabbits; and (3) infecting rabbits with pools of mutant E. coli strains to identify factors that the bacteria require to survive in rabbits. The results of these studies will improve understanding of the mechanisms by which E. coli cause disease and may provide opportunities for the development of novel tools to diagnose, treat and prevent E. coli-associated diarrhoea.Read moreRead less
Environmental Regulation Of Virulence In Attaching And Effacing Enterobacteria
Funder
National Health and Medical Research Council
Funding Amount
$569,063.00
Summary
Disease-causing bacteria must respond to the extreme conditions, such as acid and bile, which they encounter in their hosts. They achieve this by sensing their environment and activating genes that enhance their survival and ability to cause disease. In this project we will define the mechanisms by which these sensing and response pathways occur, using E. coli as a model. The information obtained from this research should lead to new strategies to treat and prevent bacterial infections.
Molecular Typing Of Salmonella Enterica Serovar Typhimurium
Funder
National Health and Medical Research Council
Funding Amount
$272,545.00
Summary
Salmonella mainly causes food poisoning and is a significant human health problem. Different Samonella forms are identified by serotyping and many serovars have been given a name . There are more than 2000 serovars. The best known serovar is Typhimurium which is the cause of 40% of salmonella infections. Typhimurium is so frequently involved in infections it is necessary to further divide it for outbreak investigations and long term monitoring of the organism. The only widely used method to subd ....Salmonella mainly causes food poisoning and is a significant human health problem. Different Samonella forms are identified by serotyping and many serovars have been given a name . There are more than 2000 serovars. The best known serovar is Typhimurium which is the cause of 40% of salmonella infections. Typhimurium is so frequently involved in infections it is necessary to further divide it for outbreak investigations and long term monitoring of the organism. The only widely used method to subdivide Typhimurium is phage typing, which is done only in major laboratories (2 in Australia). Phage typing is based on lysis patterns of a test isolate to a set of 34 phages. Phage typing has played a crucial role in tracking the organism, for example the emergence of a multidrug resistance new type (DT204c) in UK and US. The technique is simple but the problem is that reactions vary with slight change in conditions and scoring the reaction results is very subjective. We propose to replace the typing system with one based on the DNA method PCR, so it will be simple, fast and accurate. We will use a DNA fingerprinting technique called AFLP (amplified fragment length polymorphism) to find markers (DNA segments) that are specific to phage types and design PCR assays based on the markers we find. Such a typing system will retain the essence of phage typing by providing continuity of the valuable epidemiological database on phage types. Further the typing system could easily be expanded to accommodate any new types by finding more markers while the current phage typing system is very difficult to expand (last done in 1977 and is behind in our needs). This project will establish a general approach for designing typing systems based on molecular biology for other pathogens and could have a major impact on the surveillance of bacterial infections in the 21st century.Read moreRead less
QacA-mediated Multidrug Resistance And Export In Staphylococcus Aureus
Funder
National Health and Medical Research Council
Funding Amount
$497,250.00
Summary
Strains of the pathogenic bacterium Staphylococcus aureus (Golden Staph) which are resistant to almost all available anti-staphylococcal agents are responsible for serious infections among hospitalised patients; in some hospitals such outbreaks reach epidemic proportions. In these bacteria, resistance has emerged to all classes of antimicrobial agents, including antibiotics and antiseptics-disinfectants commonly used in the hospital environment, largely due to the acquisition of resistance deter ....Strains of the pathogenic bacterium Staphylococcus aureus (Golden Staph) which are resistant to almost all available anti-staphylococcal agents are responsible for serious infections among hospitalised patients; in some hospitals such outbreaks reach epidemic proportions. In these bacteria, resistance has emerged to all classes of antimicrobial agents, including antibiotics and antiseptics-disinfectants commonly used in the hospital environment, largely due to the acquisition of resistance determinants. These determinants encode for proteins which provide the bacterial cell with a range of different biochemical mechanisms to evade antibiotic chemotherapy. Specifically, this project seeks to increase our understanding of proteins which confer resistance by pumping a variety of structurally-dissimilar antimicrobials out of the bacterial cell. Proteins which recognise such a broad spectrum of compounds are called multidrug resistance proteins and present a disturbing clinical threat since the acquisition of one such system by a cell may simultaneously decrease its susceptibility to a number of antimicrobials. Similar multidrug pumps are widespread in nature and are credited for resistance to antibiotics and other chemotherapeutic drugs in many pathogenic organisms, such as the bacteria responsible for tuberculosis, and in human cancer cells. In this project, we aim to characterise the QacA multidrug resistance protein which is involved in pumping many different antimicrobial compounds from staphylococcal cells. We will identify the regions of the QacA multidrug resistance protein which bind the compounds and examine how the protein expels them to give resistance. These studies are a prerequisite for the design of more effective antibacterial compounds able to bypass or block these drug resistance pumps, and will also provide fundamental knowledge applicable to the problem of multidrug resistance in other infectious diseases and cancer.Read moreRead less
Unified Model For Group A Streptococcal Invasive Disease Initiation.
Funder
National Health and Medical Research Council
Funding Amount
$605,221.00
Summary
Streptococcus pyogenes (group A streptococcus; GAS) is a bacterium that causes human skin and throat infections as well as highly invasive diseases including necrotising fasciitis and streptococcal toxic shock-like syndrome. We have recently discovered the trigger mechanism for GAS invasive disease. We hypothesise that the initial host response at the site of infection selects for a GAS invasive phenotype. We propose to examine the chain of events which result in tissue invasion in order to unde ....Streptococcus pyogenes (group A streptococcus; GAS) is a bacterium that causes human skin and throat infections as well as highly invasive diseases including necrotising fasciitis and streptococcal toxic shock-like syndrome. We have recently discovered the trigger mechanism for GAS invasive disease. We hypothesise that the initial host response at the site of infection selects for a GAS invasive phenotype. We propose to examine the chain of events which result in tissue invasion in order to understand these disease processes and allow the development of future therapeutic interventions.Read moreRead less
A group of bacteria called Neisseria cause human-specific infections. To initiate infection, the bacteria must produce a hair-like surface structure, the pilus. The pilus consists mainly of a protein called pilin, and we now understand how pilin production is controlled. However 20 other genes are also involved in pilus production. This project aims to understand how these other genes are controlled and coordinated to assemble this structure that is central to the ability to cause disease.
Exploration Of Exposures Associated With Bedding That Are Risks For Childhood Allergy And Asthma Symptoms
Funder
National Health and Medical Research Council
Funding Amount
$263,500.00
Summary
Asthma prevalence in Australia has doubled in the last 20 years, with 1 in 4 children now affected. House dust mites are probably the single most important allergen associated with asthma. The prevalence of mite allergy is linked to exposure, and such allergy when combined with high exposure, is a potent risk factor for asthma exacerbations. The current international advice for managing mite-allergic asthma, strongly advocates the use of bedding encasings as the best way to reduce exposure. Howe ....Asthma prevalence in Australia has doubled in the last 20 years, with 1 in 4 children now affected. House dust mites are probably the single most important allergen associated with asthma. The prevalence of mite allergy is linked to exposure, and such allergy when combined with high exposure, is a potent risk factor for asthma exacerbations. The current international advice for managing mite-allergic asthma, strongly advocates the use of bedding encasings as the best way to reduce exposure. However, three recent major trials using encasings and a meta-analysis of earlier trials all fail to show a clinical benefit. One of the applicants (ET) recently showed, using expertise in measuring personal exposure, that these encasings, as used, fail to significantly reduce aeroallergen exposure. By contrast, 3 recent Australian studies, involving the applicants, AK, ALP and NG showed that feather bedding compared to synthetic bedding, was strongly protective for asthma - the opposite of public advice. The suggested mechanisms involve reduced exposure to mite allergens, or altered exposure to bacterial endotoxin, but persuasive experimental support is lacking. We also propose a novel hypothesis that feather exposure may induce allergic 'tolerance'. Currently there is a lack of certainty about valid approaches to prevent asthma, and the Global Initiative for Asthma has described the need to understand mechanisms and improve interventions as urgent. This project is an ideal opportunity to combine the expertise of the CIA (ET) in measuring airborne exposures (mite, endotoxin, proteins) with that of the others who have expertise in children's asthma, and who are already involved in two large clinical trails involving different bedding and allergen avoidance. Our measurements of these bedding exposures and their clinical outcomes will provide, for the first time, a quantitative basis to refine public health allergen-based interventions to prevent and manage asthma.Read moreRead less
Evolution And Function Of A Novel Lateral Flagellar Locus, Flag-2, In Pathogenic Escherichia Coli
Funder
National Health and Medical Research Council
Funding Amount
$465,158.00
Summary
This project will study how the bacteria that cause infant diarrhoea colonize the intestine and induce disease. We have identified a novel genetic region that allows E. coli to survive and persist in the intestine. Similar genes are also present in closely related organisms. This project will help us to undestand how new diseases evolve and emerge and may lead to the development of new vaccines to protect against infant diarrhoea.
The Roles Of Lipoprotein Multigene Families In Pathogenesis Of Mycoplasma Pneumoniae
Funder
National Health and Medical Research Council
Funding Amount
$257,036.00
Summary
Mycoplasma pneumoniae is one of the most common causes of community acquired pneumonia. Although it can usually be successfully treated with antibiotics, it can result in more severe diseases and can be difficult to diagnose accurately. It has been identified as a target for vaccine development, but this has been hampered by the limited understanding we have of how it causes disease. The attempts at vaccination that have been made have resulted in vaccines which induced more severe, rather than ....Mycoplasma pneumoniae is one of the most common causes of community acquired pneumonia. Although it can usually be successfully treated with antibiotics, it can result in more severe diseases and can be difficult to diagnose accurately. It has been identified as a target for vaccine development, but this has been hampered by the limited understanding we have of how it causes disease. The attempts at vaccination that have been made have resulted in vaccines which induced more severe, rather than less severe, disease. Investigations of several other related bacteria have shown that they are able to vary their surface proteins and thus may evade the immune system, permitting them to cause more prolonged disease. Better understanding how this occurs, and what this enables the bacteria to do, may assist in developing improved vaccine strategies. This project aims to investigate the six gene families in Mycoplasma pneumoniae which are known to encode surface proteins and establish how and why the bacteria switch from one gene to another during infection. In addition the capacity of bacteria expressing different versions of the six surface proteins to adhere to different tissues will be investigated. Once this is known, these mechanisms may be able to be specifically disrupted to prevent a strain of Mycoplasma pneumoniae from being able to establish prolonged infections. Such a strain might be a useful basis for an effective vaccine.Read moreRead less