Genome-Wide miRNA Expression Profiling of Pietrain PAM Infected with/without PRRSV

Porcine reproductive and respiratory syndrome virus (PRRSV), which causes highly significant economic losses to the swine industry worldwide, has a strong cell tropism of porcine alveolar macrophages (PAM). PAM is considered as the major sites of viral replication during acute infection period, and the immune defense cells of the lung that first contact with pathogenic microorganisms. An increasing number of studies have shown that miRNA play a vital regulatory role in immune response and development of disease. To understand the role of miRNA during PRRSV infection of PAM, using miRNA digital analysis technology based on Illumina high-throughput sequence, 6 miRNA libraries were constructed and sequenced, the miRNA expression profiles of Pietrain PAM at 9h, 36h, 60h after infected with/without PRRSV were compared in this study. 94,402,050 clean reads were obtained. 254 known porcine miRNAs were identified. 298 new candidate miRNAs were predicted. The expression of 117, 21 and 39 miRNAs are significant difference at 9h, 36h and 60h after Pietrain PAM infected with PRRSV compared with the homochronous PAM uninfected with PRRSV. 30 (9h vs 36h), 6 (36h vs 60h) significantly differently expressed miRNAs were found among different time points after PRRSV infection. Nine miRNAs are screened out to analyze the expression by real-time fluorescent quantitation PCR, which displayed a high level of concordance between the qPCR and Solexa sequencing method. These results indicate the important role of host miRNAs in modulating PRRSV infection and viral pathogenesis. Further characterization of the function and regulatory network of differently expressed miRNAs in PRRSV infection are currently in progress.