Abstract
Relative expression levels of immune- and non-immune-related mRNAs in chicken intestinal intraepithelial lymphocytes experimentally infected with Eimeria acervulina, E. maxima, or E. tenella were measured using a 10K cDNA microarray. Based on a cutoff of >2.0-fold differential expression compared with uninfected controls, relatively equal numbers of transcripts were altered by the three Eimeria infections at 1, 2, and 3 days post-primary infection. By contrast, E. tenella elicited the greatest number of altered transcripts at 4, 5, and 6 days post-primary infection, and at all time points following secondary infection. When analyzed on the basis of up- or down-regulated transcript levels over the entire 6 day infection periods, approximately equal numbers of up-regulated transcripts were detected following E. tenella primary (1,469) and secondary (1,459) infections, with a greater number of down-regulated mRNAs following secondary (1,063) vs. primary (890) infection. On the contrary, relatively few mRNA were modulated following primary infection with E. acervulina (35 up, 160 down) or E. maxima (65 up, 148 down) compared with secondary infection (E. acervulina, 1,142 up, 1,289 down; E. maxima, 368 up, 1,349 down). With all three coccidia, biological pathway analysis identified the altered transcripts as belonging to the categories of “Disease and Disorder” and “Physiological System Development and Function”. Sixteen intracellular signaling pathways were identified from the differentially expressed transcripts following Eimeria infection, with the greatest significance observed following E. acervulina infection. Taken together, this new information will expand our understanding of host-pathogen interactions in avian coccidiosis and contribute to the development of novel disease control strategies.
Highlights
Avian coccidiosis is caused by seven species of Eimeria protozoa (E. acervulina, E. maxima, E. tenella, E. mitis, E. necatrix, E. praecox, and E. brunetti) that differ in pathogenicity and immunogenicity [1,2]
Using a cutoff of .2.0-fold differential expression compared with uninfected controls, relatively equal numbers of transcripts were altered at 1, 2, and 3 days post-primary infection with E. acervulina, E. maxima, or E. tenella (Figure 1)
E. tenella elicited the greatest number of altered transcripts at 4, 5, and 6 days post-primary infection, and at all time points following secondary infection
Summary
Avian coccidiosis is caused by seven species of Eimeria protozoa (E. acervulina, E. maxima, E. tenella, E. mitis, E. necatrix, E. praecox, and E. brunetti) that differ in pathogenicity and immunogenicity [1,2]. Infection develops following ingestion of sporulated oocysts and release of sporozoites, which subsequently invade intestinal epithelial cells. Gametes are formed and fertilized to produce a zygote, which matures into an oocyst, ruptures the host cell, and is excreted in the feces. The entire cycle normally develops over the course of 4–6 days, depending on the species [3]. Prophylactic chemotherapy has been traditionally used for disease control, the emergence of drug-resistant parasites and legislative bans on the use of in-feed antibiotic growth promoters and non-therapeutic antimicrobial feed additives encourages the development of alternative coccidiosis control strategies [5].
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