MOLECULAR CHARACTERIZATION AND GASTROINTESTINAL TRACT ECOLOGY OF COMMENSAL HUMAN FOOD-BORNE BACTERIAL PATHOGENS IN THE CHICKEN
Location: Poultry Microbiological Safety Research
Title: Gene Expression Profile of Campylobacter jejuni in Response to Chicken Weep
Submitted to: Campylobacter Helicobacter and Related Organisms International Workshop
Publication Type: Abstract Only
Publication Acceptance Date: June 8, 2007
Publication Date: September 4, 2007
Citation: Simmons, M., Hiett, K.L., Stintzi, A., Seal, B.S., Frank, J.F. 2007. Gene Expression Profile of Campylobacter jejuni in Response to Chicken Weep. Campylobacter Helicobacter and Related Organisms International Workshop.
Campylobacter spp. are one of the most common causes of foodborne bacterial gastroenteritis. Handling and consumption of raw poultry products are considered to be a major source of Campylobacter induced disease in humans. There is a high incidence of Campylobacter-positive poultry carcasses, even though Campylobacter spp. are more fragile than other foodborne pathogens and lack various stress response systems. The purpose of this study is to determine if C. jejuni genes are differentially expressed upon exposure to chicken weep. Two genome sequenced strains of C. jejuni, NCTC11168 and RM1221, were grown to mid-exponential phase at 42°C in a microaerobic chamber in Mueller-Hinton biphasic cultures. RNA was extracted from cells under these conditions or upon exposure to 20%(v/v in MH broth) chicken weep for 15min or 1 hour. The RNA was reverse transcribed using random hexamers in the presence of amino-allyl dUTP. cDNAs were labeled with monoreactive dyes Cy3 and Cy5, and hybridized to a whole genome microarray of 11168 and RM1221 unique genes. In total 214 different genes were identified as differentially expressed in at least one of the 4 strain/exposure time combinations, with 106 down-regulated and 108 up-regulated.
The majority of the genes (194) were identified as differentially expressed in the first 15 minutes as opposed to the 56 identified as differentially expressed after one hour exposure to weep, suggesting rapid changes upon exposure to weep and following equilibrium. Several genes previously identified as stress response genes including, clpB(up), grpE(up), groES(up), and ahpC(down), were identified as differentially expressed. Also genes such as acnB(down), ppi(up) and spot(up), which are possibly involved in the regulation of other genes and possible virulence factors, were identified as differentially expressed. Overall this data provides insight into the changes C. jejuni must make to its transcriptome to survive on a chicken carcass.