Submitted to: Functional and Integrative Genomics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/1/2008
Publication Date: 7/1/2008
Citation: Hiett, K.L., Stintzi, A., Andacht, T.M., Kuntz, R.L., Seal, B.S. 2008. Genomic Difference between Campylobacter jejuni Isolates Identify Surface membrane and Flagellar Function Gene Products Potentially Important for Colonizing the Chicken Intestine.. Functional and Integrative Genomics. Epubed. 8(4):407-20. Interpretive Summary: The Centers for Disease Control and Prevention estimates that Campylobacter spp. are one of the leading bacterial causes of human food-borne illness in the United States. While these bacteria are associated with a variety of foods, the handling and consumption of poultry or poultry related products is considered to be a source for bacterial food-borne disease in humans. Additionally, while pathogenic in a variety of hosts such as humans, Campylobacter spp. exists in an apparently commensal relationship with poultry. The pathways involved in contamination of poultry flocks by these pathogens continue to remain unclear, therefore, effective intervention strategies are still lacking for the poultry industry. Furthermore, the mechanisms of how these bacteria interact with their host and how these organisms colonize poultry are not well defined. The identification of genes and gene products involved in Campylobacter spp. colonization of chickens is necessary for the development of intervention strategies aimed at the reduction or elimination of Campylobacter spp. in poultry. Therefore, the gene content and subsequent expression of proteins from a C. jejuni isolate that is considered a very good colonizer of chickens was compared to the gene content and proteins expression by a C. jejuni isolate that does not colonize the chicken gastrointestinal tract in as high of numbers. It was determined that a variety of genes and proteins expressed by the good chicken colonizing C. jejuni isolate were not present in the poor colonizing isolate. A majority of theses genes were located in areas of the DNA previously determined to be hyper-variable. Consequently, if interventions can be developed that disrupt specific biological functions of C. jejuni, such as attachment of the bacteria to chicken gastrointestinal cells, these bacteria could be reduced in chickens prior to processing for human consumption.
Technical Abstract: Campylobacter spp. are considered the leading bacterial etiology of acute human gastroenteritis in industrialized countries. Evidence implicates poultry as a major source of the organism for human illness; however, the factors involved in the colonization of poultry with Campylobacter spp. remain unclear. Suppressive subtractive hybridization was used to identify genomic differences between two Campylobacter jejuni isolates, 11168(GS) and A74/C, that exhibit different colonization potentials in poultry. Two hundred and forty-eight (76.5%) of the subtracted clones were determined to contain inserts of approximately 300 to 600 base pairs in size. Sequence analyses of cloned inserts revealed similarities to an anaerobic dimethyl sulfoxide reductase, several polysaccharide modification proteins, a baseplate assembly J protein, type-I and type-III restriction modification proteins, and a subtilase family serine protease. DNA hybridization analyses of a panel of 19 C. jejuni isolates recovered from diverse spatial and temporal backgrounds were performed to further determine the distribution of differentially identified gene sequences. DNA microarray analyses were performed for comparison of the colonizing isolate, A74/C, to the two genome sequenced C. jejuni isolates, 11168(GS), the chicken non-colonizer, and RM1221. A total of 90 genes (5.5%) were determined to be absent from A74/C relative to 11168(GS). Twenty-four genes unique to RM1221 relative to 11168(GS) were also determined present in A74/C. Additionally, 2-D gel electrophoresis was performed on both soluble and membrane protein extracts from 11168(GS) and A74/C. Differences in protein mobilities identified between the two isolates included the major outer membrane protein (MOMP), flagellin, and an aconitate hydratase. Several proteins including cysteine sythase, Ni/FE hydrogenase, and a glutamate binding protein were determined to be differentially present between the two C. jejuni isolates. A determination of colonization associated factors at the genome and at the proteome level should facilitate our understanding of Campylobacter spp. contamination of poultry so that targeted intervention strategies can be developed, thereby allowing the delivery of a safer product to consumers.