Liver-expressed antimicrobial peptide-2 is downregulated in Eimeria maxima-infected chickens

Avian coccidiosis is a major disease of poultry caused by the intestinal protozoa Eimeria. Aviagen line A and line B birds show differential susceptibility to Eimeria infection, with line B birds exhibiting higher lesion scores and mortality. The objective of this study was to examine differential intestinal gene expression between line A and B chicks in response to a challenge with Eimeria maxima. Following challenge with 1 x 10^4 oocysts/chick, greater than 40% of line A chicks had lesion scores of 0 to 1 (on 0 to 4 scale), similar to controls. In contrast, all line B challenged chicks at this same dose had lesion scores of 2 to 4. Total RNA was extracted from the jejunum of control and challenged chicks from both lines A and B. Microarrays were used for detecting the expression-changed genes which responded to the Eimeria challenge. Samples included: four control A chicks, two challenged A chicks with a lesion score of 1 (A/LS1), two challenged A chicks with lesion scores of 3 to 4 (A/LS3-4), four control B chicks, two challenged B chicks with lesion scores of 2 to 3 (B/LS2-3) and two challenged B chicks with lesion scores of 4 (B/LS4). The DNA microarrays were processed at the Virginia Bioinformatics Institute (Virginia Tech) core facility. The raw array data were normalized using GC-robust multiple array (GC-RMA) normalization. Analysis of variance was used for differentially expressed genes based on Welch ANOVA (P < 0.05) and probe set lists were ordered using the fold change analysis provided by GeneSpring software.