Elucidate Cellular and Molecular Mechanisms of Genetic Control of Campylobacter Colonization in Chickens Using Whole Genome Array

<p>NON-TECHNICAL SUMMARY:<br/> The poultry industry is the third largest agricultural sector in the US. Contamination of the food supply by food-borne pathogens is a serious public health concern. Campylobacter is a leading bacterial cause of human gastroenteritis in the world with over two million cases of illness and 100 deaths each year in the US. The elucidation of cellular and molecular mechanisms of the genetic control of Campylobacter colonization in the chicken gastrointestinal tract will provide information essential for the genetic improvement of resistance to bacterial colonization. Functional genomics provide powerful new tools to investigate molecular mechanisms of bacterial infection. Controlled infection with a unique C. jejuni mutant strain that poorly colonizes the ceca of chicks as well as an aggressive wild type strain in both resistant and susceptible
chicken lines will generate the novel biological resources needed to identify host responses to C. jejuni colonization at the molecular level. A whole chicken genome oligo array will be used to identify genes and gene networks related to resistance to bacterial burden in chickens. The fulfillment of the proposed study will provide a basis for the reduction of food-borne pathogen carriage, and improve consumer health and perception of animal products. Moreover, the results can advance our general understanding of signal pathway and biological processes of host-pathogen interaction.<p>
APPROACH:<br/> The objective of this project is to identify genes and/or gene signal pathway that are associated with Campylobacter colonization in chicken ceca. Genetically resistant and susceptible birds to bacterial colonization will be selected for this study. The two Campylobacter jejuni strains (wild type and mutant)will be used in this study. The wild type can naturally colonize very well in the gastrointestinal tracts, but the mutant has significantly reduced bacterial colonization. Both strains will be used to challenge resistant and susceptible birds, and important lymphoid tissues will be collected at different time points. The chicken 44K array will be used to investigate the effect of the interaction between host (resistant or susceptible) and pathogen (wild type or mutant) on genetic control of chicken resistance to C. jejuni colonization.The genes or
signature of gene clusters associated with bacterial burden in chickens will be determined by statistical methods.</p><p>
PROGRESS: <br/>2012/02 TO 2012/08 <br/>OUTPUTS: Last year, our focus has been on host innate immune response to C. jejuni infection in bursa. This year, we are focused on another important lymphoid tissue: cecum. To elucidate cellular and molecular mechanisms of resistance to C. jejuni colonization in chickens, two genetically distinct broiler lines (Line A (resistant) colonized less by C. jejuni compared to Line B (susceptible)) were inoculated with wild type (WT) or mutant (MT) C. jejuni or PBS at day of hatch. Total RNA was isolated from cecum harvested at 1, 4, 24, and 36 hrs post-inoculation. With eight biological replicates from each group at each time point, a chicken whole genome 44K array was used to profile the host innate response to C. jejuni. A total of 96 arrays were analyzed, and signal intensity of each gene was normalized using LOWESS method. A dynamic
Bayesian network machine learning approach was employed to systemically analyze the host innate response to C. jejuni. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.</p>