Abstract
The recent association between S. Enteritidis PT4 and poultry products has caused a great deal of concern from adverse publicity and with resulting national and international requirements to control the major food-poisoning Salmonella serotypes at the breeder and layer levels in order to ensure that poultry products are Salmonella-free. The exact mechanism whereby these serotypes are able to colonize the intestine of chickens is still exactly unknown. Indeed, there is increasing evidence that colonization is not solely a metabolic function but that some form of physical association with cells or an organ in the gut is involved. Thus, invasion and fimbrial genes required for colonization were identified suggesting physical contact was required. An alternative approach would be to analyze the patterns of gene expression by microarray analysis at the site of colonisation (caeca). This has been done for a number of niches and is now being applied to intra-cellular infection but has not so far been applied to the intestine. The S. Enteritidis transcriptome during the colonization of the caeca of one day chicks was characterized by Agilent microarray. The Microarray results were evaluated by real-time PCR with 95% compatibility. Fumarate respiratory and osmotic response genes were selected from the up-regulated genes and were mutated and tested in the lab for their inhibitory effect and for competitive growth under anaerobic and osmotic environment showing variable responses. There is considerable scope improvement in inactivated vaccines through a more rational approach and the work presented in this project could form the basis of such a vaccine