Modulation of microRNAs in two genetically disparate chicken lines showing different necrotic enteritis disease susceptibility.

MicroRNAs (miRNA) play a critical role in post-transcriptional regulation by influencing the 3'-UTR of target genes. Using two inbred White Leghorn chicken lines, line 6.3 and line 7.2 showing Marek's disease-resistant and -susceptible phenotypes, respectively, we used small RNA high-throughput sequencing (HTS) to investigate whether miRNAs are differently expressed in these two chicken lines after inducing necrotic enteritis (NE). The 12 miRNAs, selected from the most down-regulated or up-regulated miRNAs following NE induction, were confirmed by their expressions in real-time PCR. Among these miRNAs, miR-215, miR-217, miR-194, miR-200a, miR-200b, miR-216a, miR-216b, and miR-429 were highly expressed in intestine derived from line 7.2, whereas, miR-1782 and miR-499 were down-regulated. In spleen, miR-34b and miR-1684 were the most up-regulated miRNAs in line 6.3. Notably, five out of six target genes, CXCR5, BCL2, GJA1, TCF12, and TAB3 were differentially expressed between line 6.3 and line 7.2, and showed suppression in the MD-susceptible chicken line. Their expression levels were conversely correlated with those of miRNA obtained from both HTS and quantitative real-time PCR. These results suggest that some miRNAs are differentially altered in response to NE and they modulate the expression of their target genes in the two inbred lines. Collectively, HTS analysis of intestinal miRNAs from NE-afflicted inbred chickens showing different disease phenotypes led to the identification of host immunity genes regulated by miRNA. Future studies of the function of these miRNAs and their target genes in the host will lead to enhanced understanding of molecular mechanisms controlling host-pathogen interaction in NE.