iTRAQ-based quantitative subcellular proteomic analysis of Avibirnavirus-infected cells.

Infectious bursal disease virus (IBDV) enters the host cells via endocytic pathway to achieve viral replication in the cytoplasm. Here, we performed LC-MS/MS coupled with isobaric tags for relative and absolute quantification labeling of differentially abundant proteins of IBDV-infected cells using a subcellular fractionation strategy. We show that the viral infection regulates the abundance and/or subcellular localization of 3211 proteins during early infection. In total, 23 cellular proteins in the cytoplasmic proteome and 34 in the nuclear proteome were significantly altered after virus infection. These differentially abundant proteins are involved in such biological processes as immune response, signal transduction, RNA processing, macromolecular biosynthesis, energy metabolism, virus binding, and cellular apoptosis. Moreover, transcriptional profiles of the 25 genes corresponding to the identified proteins were analyzed by quantitative real-time RT-PCR. Ingenuity Pathway Analysis clustered the differentially abundant proteins primarily into the mTOR pathway, PI3K/Akt pathway, and interferon-β signaling cascades. Confocal microscopy showed colocalization of the viral protein VP3 with host proteins heterogeneous nuclear ribonucleoprotein H1, nuclear factor 45, apoptosis inhibitor 5, nuclear protein localization protein 4 and DEAD-box RNA helicase 42 during the virus infection. Together, these identified subcellular constituents provide important information for understanding host-IBDV interactions and underlying mechanisms of IBDV infection and pathogenesis.