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 on 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, quantitative phosphoproteomic analysis of human lung cell line (A549) infected with 2009 pandemic influenza virus A (H1N1) virus was performed.
Phosphopeptides were enriched from tryptic digests of total
protein of infected and mock-infected cells 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 43 upregulated and 35 downregulated
proteins during influenza virus
infection. Gene ontology enrichment analysis showed that majority of the identified
proteins are
phosphoproteins involved in RNA processing, immune system process and response to
infection. Host-virus interaction network analysis had identified 23 densely connected subnetworks. Of which, 13 subnetworks contained
proteins with altered phosphorylation levels during by influenza virus
infection. Our results will help to identify potential drug targets that can be pursued for
influenza antiviral drug development.