FUNCTIONAL GENOMICS AND GENETIC ANALYSIS OF THE INNATE IMMUNE RESPONSE REQUIRED TO RESIST FOOD-BORNE BACTERIAL INFECTIONS IN POULTRY
Location: Food and Feed Safety Research
Title: THE FEATHERING GENE IS LINKED TO DEGRANULATION AND OXIDATIVE BURST NOT CYTOKINE/CHEMOKINE MRNA EXPRESSION LEVELS OR SALMONELLA ENTERITIDIS ORGAN INVASION IN BROILERS
Research conducted cooperatively with:
| Cobb-Vantress, Inc.|
Submitted to: Avian Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 28, 2006
Publication Date: December 7, 2006
Citation: Swaggerty, C.L., He, H., Genovese, K.J., Kaiser, P., Pevzner, I.Y., Kogut, M.H. 2006. The feathering gene is linked to degranulation and oxidative burst not cytokine/chemokine mRNA expression levels or Salmonella enteritidis organ invasion in broilers. Avian Pathology. 35:465-470.
Interpretive Summary: During the first week of life, baby chickens are likely to get infected with germs, including Salmonella which can make people sick when they eat the infected chickens. Baby chickens have blood cells called heterophils that can help them prevent these infections. We have found that the type of feathers (fast or slow growing) a bird has may have an affect on the heterophils and how well they function to eliminate Salmonella and other germs. The objective of this research was to determine for certain what the role of feathering is with regard to heterophil function and how well the different chickens can fight off Salmonella infections. We found that heterophils from fast feathering chickens have better heterophil function when looked at in a test tube, but that the feathering type was not involved in how well the chicken fights off Salmonella infections. These experiments are important to the commercial poultry breeders because they use both fast and slow feathering-type chickens. If the poultry companies know which chickens are more resistant to Salmonella, they will be able to use a more resistant chicken to produce the chicken and eggs that end up on our tables. A resistant chicken is going to be stronger and will fight off infections better; therefore, people would be less likely to get sick from eating contaminated poultry.
In the past, we showed differences in heterophil function between parental broilers Lines A (fast [F] feathering)>B (slow [S] feathering) and their F1 reciprocal crosses (Line D [F]>C [S]), indicating the feathering gene is associated with heterophil function. In the present study, we evaluated the linkage of the feathering gene to heterophil function, pro-inflammatory cytokine/chemokine mRNA expression, and resistance to Salmonella enteritidis (SE) organ invasion. Heterophils were isolated from two-day-old chickens (C and D) separated into males and females (SM, SF and FM, FF, respectively). With respect to the feathering gene, males are the same (K/k+) while females are different (SF=K/-; FF=k+/-). Therefore, if function is linked to the feathering gene, FF would be more efficient than SF while the males would be the same. Heterophil functions of degranulation and oxidative burst were measured. FF heterophils (183±8.9) released more beta-D-glucuronidase than SF heterophils (149±3.7); FF heterophils (4.6×10**4) generated a greater oxidative burst compared to SF heterophils (4.2×10**4) (p less than or equal to 0.04). Interleukin-6, CXCLi2, and interferon-alpha mRNA expression were quantitated by real-time-quantitative-RT-PCR. No differences were observed between SM and FM or between SF and FF heterophils. Lastly, day-old chickens were administered SE and liver/spleen organ invasion quantitated. No differences were observed between the number of SE-positive FF and SF chickens but FM were more (p less than or equal to 0.04) resistant than SM chickens. The data indicate degranulation and oxidative burst are linked with the feathering gene; however, cytokine mRNA expression is not. Further, susceptibility to in vitro SE organ invasion is not linked to the feathering gene.