○ダパト クライド1,橋本 義哉2,齋藤 玲子1,鈴木 宏3,堀米 恒好2 1 Division of International Health (Public Health), Graduate School of Medical and Dental Sciences, Niigata University,2 Department of Chemistry, Faculty of Science, Niigata University, 3 School of Nursing, Niigata Seiryo University The emergence of antiviral drug-resistant influenza viruses highlights the need for alternative therapeutic strategies. Elucidation of host factors required during virus infection provides information not only on the signaling pathways involved but also to the identification of novel drug targets. RNA interference screening method had been utilized by several studies to determine these host factors; however, proteomics data on influenza host factors are currently limited. In this study, we performed a quantitative phosphoproteomic analysis of a human lung cell line (A549) infected with influenza virus by mass spectrometry-based method. To compare the phosphorylation profile of infected and mock-infected cells, tryptic protein digests were enriched for phosphopeptides using a titania column on an automated purification system followed by iTRAQ labeling. Identification and quantitative analysis of iTRAQ-labeled phosphopeptides were performed using LC-MS/MS. We identified 366 phosphorylation sites on 283 proteins. Of these, we detected 44 proteins with increased phosphorylation and 41 proteins with decreased phosphorylation during influenza virus infection. GO term analysis showed that proteins involved in the regulation of kinase and phosphatase activities are highly enriched. Host-virus interaction network analysis have identified 20 densely connected subnetworks including 71 host factors involved in RNA binding and splicing, vesicle-mediated transport, ATP binding, regulation of protein import into nucleus and nuclear export, regulation of PKC, MAPK, NF-kB, PIP3, and GPCR signaling pathways, binding to proteins in adherens junction, chromatin, cytoskeleton, replication, posttranscriptional regulation, and translation. Of the 71 host factors that were queried in the DrugBank database, 13 FDA-approved and 31 experimental drugs were identified. Our results lead to the identification of potential drugs and drug targets that can be pursued for influenza antiviral drug development.