Construction And Analysis Of The Regulated Networks Of Differentially Expressed Mirna Involved In Alveolar Macrophages From Piglets Infected With Influenza A Virus(H1N1)

Influenza virus is an RNA virus which can lead to seasonal influenza or even worldwide pandemic. It can cause acute respiratory infections in human and animals. In2009, a novel swine-origin H1N1influenza virus spread all’over the world and caused great damage to public health and the development of economy. Therefore, understanding the host pathogenic mechanism of H1N1influenza virus is of great importance.H1N1influenza virus infection can cause differential expression (DE) of host miRNA. In this study, we identified DE miRNAs by analyzing data from deep sequencing of alveolar macrophages from piglets infected with influenza A virus (H1N1) at different time post infection.Compared with the control, a total of70miRNAs showing differential expression after inoculation on day4post infection (PID),8of which were up-regulated and the other62were down-regulated. By predicting the targets of DE miRNAs, we found that these DE miRNAs were involved in many vital function classes, mainly including immune response, inflammatory response, focal adhesion, apoptosis and signal transduction. Through the pathway analysis, the significant pathways mainly concerned with MAPK, Focal adhesion, Cytokine-cytokine receptor interaction, Chemokine signaling pathway, T cell receptor signaling pathway, Toll like receptor signaling pathway and Apoptosis, suggesting that the host may activate those pathways to resist H1N1virus infection. On PID7, only16miRNA showed differential expression, of which6were up-regulated. The predominant functions of target genes mainly included development, metabolism and transcription. The significant pathways mainly switched to MAPK signaling pathway, P53signaling pathway, but their numbers reduced, which suggested that the host may start to repair tissue damage. There were56DE miRNAs between PID4and PID7, most of them were up-regulated and related with immune response, focal adhesion and apoptosis, showing that these functions may be inhibited. Moreover, we constructed a transcription factor mediated miRNA-mRNA network. Through GO analysis, we got a large number of DE miRNAs associated with the immune and inflammatory response on PID4, suggesting that the host may take different strategies to activate immune and inflammatory response to prevent virus infections, the overabundant production of immune and inflammatory responses are closely related with the signs and pathogenesis of influenza infection. However, on PID7, host immune and inflammatory responses were significantly weakened, which indicated that the host may start to repair excessive tissue damage.We mapped target genes of DE miRNAs to proteins and obtained the protein-protein interaction networks regulated by DE miRNAs at different time points. By topological analysis, we identified10hub proteins in each network and found that A7XNS1encoded by NFKB1was the largest degree protein, which was closely related with immune and inflammatory response.The study showed that the miRNAs expressed differently on PID0, PID4and PID7. Exploring differentially expressed miRNAs regulated network at different periods, it could help to screen the potential host miRNAs involved in piglets alveolar macrophages and further understand the pathogenesis associated with H1N1infection in pigs.