Common and Unique Gene Expression of Avian Macrophages in Response to Three Major Eimeria Species

Rami A. Dalloul,1,* Hyun S. Lillehoj1,# Travis W. Bliss,2 Yeong-Ho Hong1 and Calvin L. Keeler2
1Animal Parasitic Diseases Laboratory, Animal and Natural Resources Institute, USDA-ARS, Beltsville, MD 20705, USA
2Department of Animal and Food Sciences, College of Agriculture and Natural Resources, University of Delaware, Newark, DE 19716, USA


ABSTRACT
Host immune responses to Eimeria are very complex and involve both innate and adaptive immunities. The chicken intestine is an intricate and dynamic ecosystem where immune elements interact with antigenic components of pathogens as well as with those of nutrients, exogenous compounds and microflora. These immune responses are also influenced by the host genetic makeup and their interactions are essential in the defense against enteric pathogens like Eimeria. The outcomes of these complex interactions determine resistance to infection, and the development of genomic tools and techniques allows for analysis of such multiple and complex host responses. Macrophages and intraepithelial lymphocytes (IELs) are critical components of the intestinal immune system and have been shown to play significant roles in both the innate and acquired immune responses to Eimeria. In order to better understand the immunobiology of host-parasite interaction, avian macrophage and IEL cDNA microarrays were used. Using avian macrophage microarray containing 4,906 unique gene elements obtained from chicken macrophage cDNA library and spotted in triplicates, we identified important host genes which expression were enhanced following infection of macrophages with sporozoites of E. tenella, E. acervulina, and E. maxima. Genes which showed significant expression were confirmed using real-time quantitative PCR. Host genes, which expression changed significantly after infection with Eimeria, included many genes encoding cytokines and chemokines that are associated with inflammatory responses. Among key cytokine genes that increased shortly after infection IFN-g, IL-2, IL-15, IL-16 IL-17, and IL-18 were included. Furthermore, we prepared a cDNA library from intestinal IELs of Eimeria-infected chickens and constructed a small intestinal microarray containing over 10,000 unique elements spotted in duplicates. Investigations are currently under way to study kinetic gene expression in mucosal scrapings of birds infected by one of the three Eimeria species. Further analysis of these expression patterns will contribute to a better understanding of the mechanisms underlying resistance and susceptibility to coccidiosis.


*Presenting author
#Corresponding author: hlilleho@anri.barc.usda.gov