|SU, SHENGCHEN - Virginia Tech|
|DWYER, D.M. - Virginia Tech|
|WONG, ERIC - Virginia Tech|
Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/23/2016
Publication Date: 5/1/2017
Citation: Su, S., Dwyer, D., Miska, K.B., Fetterer, R.H., Jenkins, M.C., Wong, E.A. 2017. Expression of avian beta-defensins in the intestine of Eimeria-challenged chickens. Poultry Science. doi: 10.3382/ps/pew468.
Interpretive Summary: Coccidiosis is an intestinal disease responsible for large economic losses to the poultry industry worldwide. This disease is caused by a single celled parasite Eimeria. Several species of Eimeria are responsible for causing coccidiosis and each species infects a different portion of the gut. At the height of infection the parasites cause damage to the intestine, resulting in loss of appetite, diarrhea, and sometimes death. The goal of the present study was to determine how three different species of Eimeria affect the ability of the gut tissues to generate molecules called defensins that are part of the first line of defense (innate immunity) against microorganisms that cause disease in the intestines of infected chickens. The results indicate that when birds become infected with either, Eimeria maxima, E. acervulina, and E. tenella, species-specific changes in production of defensin molecules occur. Eimeria acervulina caused predominantly a decrease in defensin expression. Eimeria maxima infection resulted in some defensins being up- and some being down regulated, while E. tenella infection did not cause any change in defensin expression. This study shows that some Eimeria species can have an effect on molecules that are part of the innate immune system, but these effects are species specific. Therefore it is likely that the innate immune system of the chicken responds differently depending on which species of Eimeria is present during infection.
Technical Abstract: Avian coccidiosis is caused by the intracellular protozoa Eimeria. The site of invasion and lesions in the intestine is species-specific; for example, E. acervulina mainly affects the duodenum, E. maxima the jejunum, and E. tenella the ceca. Lesions in the intestinal mucosa reduce feed efficiency and body weight gain. The resultant damaged intestinal barrier leads to bacterial infection, which can increase mortality in birds. Avian beta-defensins (AvBDs) are cationic host defense peptides (HDPs), which are expressed in epithelial cells as a component of the innate immune system. The objective of this study was to compare the expression of AvBD family members 1, 6, 8, 10, 11, 12 and 13 in broilers challenged with either E. acervulina, E. maxima, or E. tenella. Duodenum, jejunum, ileum and ceca were collected 7 d post challenge. E. acervulina challenge resulted in downregulation of AvBD1, AvBD6, AvBD10, AvBD11, AvBD12 and AvBD13 in the duodenum. E. maxima challenge caused downregulation of AvBD6, AvBD10 and AvBD11 in the duodenum, downregulation of AvBD10 in the jejunum, but upregulation of AvBD8 and AvBD13 in the ceca. Interestingly, E. tenella challenge showed no change in AvBD expression in any tissue. Thus the cellular immune response to the different Eimeria shows species- and tissue-specificity.