Acid Resistance Mechanisms Of Helicobacter Pylori And Their Impact On Gastric Colonisation
Funder
National Health and Medical Research Council
Funding Amount
$287,036.00
Summary
The gastric bacterium, Helicobacter pylori, infects more than half the population of the globe. H. pylori may cause either no symptomatic disease, induce peptic ulcers or be responsible for one of the major killing cancers, gastric cancer. Millions die or suffer from this infection each year. Yet we are remarkably ignorant of why the infection causes these different patterns of disease. This project aims to provide evidence to show that the very mechanism the bacterium has acquired to help it re ....The gastric bacterium, Helicobacter pylori, infects more than half the population of the globe. H. pylori may cause either no symptomatic disease, induce peptic ulcers or be responsible for one of the major killing cancers, gastric cancer. Millions die or suffer from this infection each year. Yet we are remarkably ignorant of why the infection causes these different patterns of disease. This project aims to provide evidence to show that the very mechanism the bacterium has acquired to help it resist stomach acid and so live in the stomach, is responsible for these differences. I.e. The organism lives in different parts of the stomach due to differences in local acid at that site. If the acid in a particular part of the stomach is too high, the acid resistance mechanism cannot cope. If the acid is too low, the organism also cannot grow well. Because the bacterium has evolved to only thrive in a relatively narrow range of acid, it will behave very differently in these different parts of the stomach. This results in different diseases. Various populations in different countries of the world have different levels of acid production and this also explains why in some countries duodenal ulcers predominate and in others gastric ulcer- gastric cancer is the norm. Showing why H. pylori lives where it lives will provide fundamental information relevant to understanding some of the world s major diseases and will also provides insights relevant to the design of new therapeutic approaches.Read moreRead less
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