Current Approaches on Viral Infection: Proteomics and Functional Validations

Zheng, Jie; Tan, Boon Huan; Sugrue, Richard; Tang, Kai

For most viruses, the detailed mechanism of virus and host signaling pathways associated with virus survival remains elusive. Since lipid raft plays important roles in virus assembly, signaling, and sorting pathways, delineation of those host proteins associated with lipid rafts could assist to understand the key regulators and mediators involved in viral maturation. Mannova and Beretta (2005) used 2D gel coupled with LC-ESI/Q-TOF/MS-MS to characterize the protein contents of lipid rafts of hepatitis C virus infected cell membranes. N-Ras was identified as a key activator of PI3K-Akt-mTOR pathway and it was important for cellular signaling behaviors. siRNA silencing of N-Ras was observed to inhibit the host PI3K-Akt-mTOR pathway and thus enhanced the HCV replications. A similar effect was observed when cells were treated with PI3K inhibitor LY294002 or transfected with mTOR siRNA. In another study, Gaither et al. (2010) utilized drug inhibition assays, iTRAQ coupled with LC-MS/MS, and RNAi screening to identify key factors involved in HCV replication pathways. Cyclophilins A, H, 40, and E were identified and validated to associate with multiple signaling pathways of HCV replication. One cyclophilin inhibitor NIM811 could strongly suppress these multiple pathways and result in reduced virus release. In another study by Hwang et al. (2007) annexin 1 was discovered to be a key effector to apoptosis pathways associated with infectious pancreatic necrosis virus (IPNV) infected cells. They employed 2D gel electrophoresis and MALDI TOF/TOF MS and identified annexin 1 as an up-regulated protein upon virus infection. SiRNA-mediated knockdown of annexin 1 not only increased the apoptotic effects of cell death, but also suppressed viral protein synthesis until 10 h post infection.