Identification And Characterization Of Differential MiRNAs In Lung Tissue Of Different Pig Breeds After PCV2 Infection

Porcine circovirus(PCV) is a kind of nonenveloped, icosahedral virus containing a circular single-stranded DNA genome, which is one of the minimum DNA animal viruses. Porcine circovirus can be divided into two serotypes: PC V1 and PCV2, PCV1 is unpathogenic while PCV2 is pathogenic. Porcine circovirus type 2(PCV2) is the primary cause of Postweaning Multisystemic Wasting Syndrome(PMWS) in pigs which has been devastating the swine industry worldwide since the 1990 s. What’s more, PCV2 was proved inducing immunosuppression in pigs. The lung was the main target organ of PCV2 infected pigs. As one of the post-transcriptional gene regulatory mechanism, miRN A is highly conserved in animal evolution and exhibits spatial and temporal expression patterns. miRN A was involved in a wide range of life processes which include anti-disease, apoptosis, proliferation and hormone secretion.Laiwu pig(a Chinese domestic breed) has been proved different from western commercial pig breeds in meat quality, adipogenesis and disease-resistance. Although micro RNAs expression profiles have been performed in PRRS, PPV, and many important pig diseases, PCV2, however had not been reported. In this study, four libraries of lung tissue infected with PCV2 were constructed(uninfected Laiwu pigs, infected Laiwu pigs, uninfected Y-L pigs and infected Y- L pigs). High throughput sequencing technique and bioinformatics then were used to determine the abundance and differential expression of the micro RNAs. In total, 282 known and 108 novel miRN As were identified. Further analysis was also carried out here. All the results were listed as follows.(a) miRN A expression profile was analyzed here for Laiwu and Yorkshire- Landrance hybrid breed after PCV2 infection. 23 miRN As were significantly differentially expressed with both P-value< 0.05 and Fold-change=log2(treatment/control)>1 or <-1. The regulation of five with amounts and large change of these miRN As(ssc- miR-122, 192, 451, 486, and 504) was confirmed by quantitative RT-PCR. Which verified the results of deep-seq. Among them, miR-122, 192, 451 and 486 were up-regulated while miR-504 was down-regulated.(b) DIAN A-mirPath analysis was used here to investigate the underline profiles of four up-regulated miRN As(ssc- miR-122, 192, 451 and 486). We found that the main target genes of them clustered in Insulin signaling pathway, mTOR signaling pathway, Non-small cell lung cancer and Leukocyte transendothelial migration pathways which correlated to cell apoptosis and immune reactions. Further analysis showed that two of the target genes, NFAT5 and IGF1 both participated in several relevant pathways and targeted more than one miRN As in the four ups.In conclusion, the present study provides a comprehensive view of miRNA expression profile of Laiwu and Y- L pigs after PCV2 infection. Here, we identified several important miRN As changed significantly after infection. And DIANA- mirPath analysis of four up-regulated miRN As shows some important pathways and genes. These results not only contribute to the understanding of the porcine miRN A expression profiles of PCV2 infection but also provide a valuable resource for future pig breeding research in PCV2 resistance.