* To produce a genetically detoxified H. pylori cytotoxin protein suitable for evaluation as a vaccine candidate.
* To assess the genetic variability of Chinese isolates of H. pylori, and to evaluate the relationship of this variability to the incidence of severe disease.
* To test in the mouse model, vaccine candidates which show promise in protecting against European strains of H. pylori for their capacity to induce protection against infection by virulent Chinese strains.
* Identification of biologically relevant regions of the VacA protein.
* A genetically detoxified and antigenically intact cytotoxin molecule as a vaccine candidate.
* Serological data on the association of infection with Type I, VacA and CagA expressing strains with gastroduodenal disease in China.
* Genotypic and phenotypic data on the variation of H. pylori strains in clinical isolates form Chinese patients and their assocation with disease.
* Pathogenicity in vivo and in vitro of clinical isolates from China related to their genotype and phenotype.
* Evaluation of the cytotoxin toxoids in conferring protective immunity against infection by European and Chinese strains of H. pylori.
* A bank of monclonal antibodies raised against purified native toxin wil be screened for their ability to neutralize purified toxin.
* Sequences coding for potentially non-toxic VacA proteins willl be created in
E. coli by site directed mutagensis.
Mutated genes constructed in E. coli will be transferred into H. pylori.
* Mutated toxin proteins will be tested for their ability to induce gastric lesions after oral administration to mice.
* Sera from Chinese patients undergoing routine endoscopy will be analysed for their ability to recognize CagA, VacA and other H. pylori antigens to ascertain any correlation with particular conditions such as duodenal ulcer and gastric cancer.
* Strains isolated by endoscopy from Chinese patients will be analysed for the presence of the CagA genotype and by immunoblot for expression of CagA and VacA proteins.
* Selected isolated of different genotype and phenotype will be adapted to mice by sequential passage.
* Non-toxic VacA proteins will be tested for their ability to protect mice from infection with European and Chinese strains of H. pylori adapted to colonization of mice.
Funding SchemeCSC - Cost-sharing contracts
LS9 7TF Leeds